diff mbox

[fortran] Reduce stack use in blocked matmul

Message ID 2f81b4a0-79b7-1366-56f3-7355bb9f264a@netcologne.de
State New
Headers show

Commit Message

Thomas Koenig May 5, 2017, 8:31 p.m. UTC 
Hello world,

the attached patch reduces the stack usage by the blocked
version of matmul for cases where we don't need the full buffer.
This should improve stack usage.

Regression-tested.  I also added a stress test (around 3 secs of
CPU time on my system), it will only run once due to the "dg-do  run"
hack).

OK for trunk?

	Thomas

2017-05-05  Thomas Koenig  <tkoenig@gcc.gnu.org>

         PR fortran/80602
         * m4/matmul_internal.m4:  'matmul_name`:  Change
         t1 to a VLA of the required size.
         * generated/matmul_c10.c: Regenerated.
         * generated/matmul_c16.c: Regenerated.
         * generated/matmul_c4.c: Regenerated.
         * generated/matmul_c8.c: Regenerated.
         * generated/matmul_i1.c: Regenerated.
         * generated/matmul_i16.c: Regenerated.
         * generated/matmul_i2.c: Regenerated.
         * generated/matmul_i4.c: Regenerated.
         * generated/matmul_i8.c: Regenerated.
         * generated/matmul_r10.c: Regenerated.
         * generated/matmul_r16.c: Regenerated.
         * generated/matmul_r4.c: Regenerated.
         * generated/matmul_r8.c: Regenerated.

2017-05-05  Thomas Koenig  <tkoenig@gcc.gnu.org>

         PR fortran/80602
         * gfortran.dg/matmul_15.f90:  New test case.

Comments

Jerry DeLisle May 8, 2017, 4:58 p.m. UTC | #1 
On 05/05/2017 01:31 PM, Thomas Koenig wrote:
> Hello world,
> 
> the attached patch reduces the stack usage by the blocked
> version of matmul for cases where we don't need the full buffer.
> This should improve stack usage.
> 
> Regression-tested.  I also added a stress test (around 3 secs of
> CPU time on my system), it will only run once due to the "dg-do  run"
> hack).
> 
> OK for trunk?
> 

OK, thanks.

Jerry
Thomas Koenig May 8, 2017, 7:29 p.m. UTC | #2 
Am 08.05.2017 um 18:58 schrieb Jerry DeLisle:

he attached patch reduces the stack usage by the blocked
>> version of matmul for cases where we don't need the full buffer.
>> This should improve stack usage.
>>
>> OK for trunk?
>>
> 
> OK, thanks.

Is this something we should consider for backporting to gcc-7?
I think the large block size caused
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79876 .

That one was fixed by adjusting the ridiculously low
stack size for multi-threaded applications on OSX, but
the underlying problem could still bite somewhere or
somebody else.

Opinions?

Regards

	Thomas
Jerry DeLisle May 8, 2017, 9 p.m. UTC | #3 
On 05/08/2017 12:29 PM, Thomas Koenig wrote:
> Am 08.05.2017 um 18:58 schrieb Jerry DeLisle:
> 
> he attached patch reduces the stack usage by the blocked
>>> version of matmul for cases where we don't need the full buffer.
>>> This should improve stack usage.
>>>
>>> OK for trunk?
>>>
>>
>> OK, thanks.
> 
> Is this something we should consider for backporting to gcc-7?
> I think the large block size caused
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79876 .
> 
> That one was fixed by adjusting the ridiculously low
> stack size for multi-threaded applications on OSX, but
> the underlying problem could still bite somewhere or
> somebody else.
> 
> Opinions?
> 

I think it should be back ported since we really changed the matmul and this was
a fallout and using a to much stack might end up being a regression.

OK to back port.

Jerry
Andreas Schwab May 9, 2017, 10:43 a.m. UTC | #4 
On Mai 05 2017, Thomas Koenig <tkoenig@netcologne.de> wrote:

> @@ -227,6 +226,17 @@ sinclude(`matmul_asm_'rtype_code`.m4')dnl
>        if (m == 0 || n == 0 || k == 0)
>  	return;
>  
> +      /* Adjust size of t1 to what is needed.  */
> +      index_type t1_dim;
> +      t1_dim = (a_dim1-1) * 256 + b_dim1;
> +      if (t1_dim > 65536)
> +	t1_dim = 65536;

What happens if (a_dim1-1) * 256 + b_dim1 > 65536?

Andreas.
Christophe Lyon May 9, 2017, 12:41 p.m. UTC | #5 
Hi,

On 8 May 2017 at 18:58, Jerry DeLisle <jvdelisle@charter.net> wrote:
> On 05/05/2017 01:31 PM, Thomas Koenig wrote:
>> Hello world,
>>
>> the attached patch reduces the stack usage by the blocked
>> version of matmul for cases where we don't need the full buffer.
>> This should improve stack usage.
>>
>> Regression-tested.  I also added a stress test (around 3 secs of
>> CPU time on my system), it will only run once due to the "dg-do  run"
>> hack).
>>
>> OK for trunk?
>>
>
> OK, thanks.
>

Since this was committed (r247753), I've noticed the following failures
on arm* targets:
  - PASS now FAIL             [PASS => FAIL]:

  Executed from: gfortran.dg/dg.exp
    gfortran.dg/allocatable_function_8.f90   -O0  execution test
    gfortran.dg/allocatable_function_8.f90   -O1  execution test
    gfortran.dg/allocatable_function_8.f90   -O2  execution test
    gfortran.dg/allocatable_function_8.f90   -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions  execution
test
    gfortran.dg/allocatable_function_8.f90   -O3 -g  execution test
    gfortran.dg/allocatable_function_8.f90   -Os  execution test
    gfortran.dg/generic_20.f90   -O0  execution test
    gfortran.dg/generic_20.f90   -O1  execution test
    gfortran.dg/generic_20.f90   -O2  execution test
    gfortran.dg/generic_20.f90   -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions  execution
test
    gfortran.dg/generic_20.f90   -O3 -g  execution test
    gfortran.dg/generic_20.f90   -Os  execution test
    gfortran.dg/matmul_6.f90   -O0  execution test
    gfortran.dg/matmul_bounds_6.f90   -O0  execution test
    gfortran.dg/matmul_bounds_6.f90   -O1  execution test
    gfortran.dg/matmul_bounds_6.f90   -O2  execution test
    gfortran.dg/matmul_bounds_6.f90   -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions  execution
test
    gfortran.dg/matmul_bounds_6.f90   -O3 -g  execution test
    gfortran.dg/matmul_bounds_6.f90   -Os  execution test
    gfortran.dg/operator_1.f90   -O0  execution test
  Executed from: gfortran.fortran-torture/execute/execute.exp
    gfortran.fortran-torture/execute/intrinsic_matmul.f90 execution,  -O0

and the new tests fail too:

  - FAIL appears              [     => FAIL]:

  Executed from: gfortran.dg/dg.exp
    gfortran.dg/matmul_15.f90   -O  execution test
    gfortran.dg/matmul_bounds_5.f90   -O0  output pattern test, is
qemu: uncaught target signal 11 (Segmentation fault) - core dumped

Christophe


> Jerry
Thomas Koenig May 9, 2017, 5:15 p.m. UTC | #6 
Am 09.05.2017 um 12:43 schrieb Andreas Schwab:
> On Mai 05 2017, Thomas Koenig <tkoenig@netcologne.de> wrote:
> 
>> @@ -227,6 +226,17 @@ sinclude(`matmul_asm_'rtype_code`.m4')dnl
>>         if (m == 0 || n == 0 || k == 0)
>>   	return;
>>   
>> +      /* Adjust size of t1 to what is needed.  */
>> +      index_type t1_dim;
>> +      t1_dim = (a_dim1-1) * 256 + b_dim1;
>> +      if (t1_dim > 65536)
>> +	t1_dim = 65536;
> 
> What happens if (a_dim1-1) * 256 + b_dim1 > 65536?

t1 is an auxiliary variable for blocking.  If that
condition is true, blocking starts to happen.

Regards

	Thomas
Andreas Schwab May 10, 2017, 7:30 a.m. UTC | #7 
On Mai 05 2017, Thomas Koenig <tkoenig@netcologne.de> wrote:

> @@ -227,6 +226,17 @@ sinclude(`matmul_asm_'rtype_code`.m4')dnl
>        if (m == 0 || n == 0 || k == 0)
>  	return;
>  
> +      /* Adjust size of t1 to what is needed.  */
> +      index_type t1_dim;
> +      t1_dim = (a_dim1-1) * 256 + b_dim1;
> +      if (t1_dim > 65536)
> +	t1_dim = 65536;
> +
> +#pragma GCC diagnostic push
> +#pragma GCC diagnostic ignored "-Wvla"
> +      'rtype_name` t1[t1_dim]; /* was [256][256] */

That does the wrong thing if b_dim1 == 0xDEADBEEF.

(gdb) p (a_dim1-1) * 256 + b_dim1
$2 = -764456190

Andreas.
Thomas Koenig May 10, 2017, 3:42 p.m. UTC | #8 
Hi Andreas,

>> +      index_type t1_dim;
>> +      t1_dim = (a_dim1-1) * 256 + b_dim1;
>> +      if (t1_dim > 65536)
>> +	t1_dim = 65536;
>> +
>> +#pragma GCC diagnostic push
>> +#pragma GCC diagnostic ignored "-Wvla"
>> +      'rtype_name` t1[t1_dim]; /* was [256][256] */
> That does the wrong thing if b_dim1 == 0xDEADBEEF.
> 
> (gdb) p (a_dim1-1) * 256 + b_dim1
> $2 = -764456190

A look into the source code shows that b_dim1 is index_type,
which is 32 bits on 32-bit sytems and 64 bits on 64-bit system.

Now, consider if it is possible to declare an array on a 32-bit
system where the number of elements along one direction exceeds 2**31-1
(so sign extension would come into play), or if it would be
possible to declare an array on a 64-bit system where the number of
elements along one direction exceeds 2**63-1.

If you manage to come up with a legal Fortran testcas which
sets b_dim1 to 0xdeadbeef, I owe you a beer :-)

Regards

	Thomas
Thomas Koenig May 10, 2017, 3:54 p.m. UTC | #9 
Am 10.05.2017 um 17:42 schrieb Thomas Koenig:
> 
> If you manage to come up with a legal Fortran testcas which
> sets b_dim1 to 0xdeadbeef, I owe you a beer :-)

... on a 32-bit system, of course.
Andreas Schwab May 10, 2017, 3:56 p.m. UTC | #10 
On Mai 10 2017, Thomas Koenig <tkoenig@netcologne.de> wrote:

> If you manage to come up with a legal Fortran testcas which
> sets b_dim1 to 0xdeadbeef, I owe you a beer :-)

grep is your friend.

Andreas.
Andreas Schwab May 10, 2017, 4:06 p.m. UTC | #11 
On Mai 10 2017, Thomas Koenig <tkoenig@netcologne.de> wrote:

> ... on a 32-bit system, of course.

http://gcc.gnu.org/ml/gcc-testresults/2017-05/msg01063.html

FAIL: gfortran.dg/generic_20.f90   -O0  execution test
FAIL: gfortran.dg/generic_20.f90   -O1  execution test
FAIL: gfortran.dg/generic_20.f90   -O2  execution test
FAIL: gfortran.dg/generic_20.f90   -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions  execution test
FAIL: gfortran.dg/generic_20.f90   -O3 -g  execution test
FAIL: gfortran.dg/generic_20.f90   -Os  execution test
FAIL: gfortran.dg/matmul_6.f90   -O0  execution test
FAIL: gfortran.dg/matmul_bounds_5.f90   -O0  output pattern test
FAIL: gfortran.dg/matmul_bounds_6.f90   -O0  execution test
FAIL: gfortran.dg/matmul_bounds_6.f90   -O1  execution test
FAIL: gfortran.dg/matmul_bounds_6.f90   -O2  execution test
FAIL: gfortran.dg/matmul_bounds_6.f90   -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions  execution test
FAIL: gfortran.dg/matmul_bounds_6.f90   -O3 -g  execution test
FAIL: gfortran.dg/matmul_bounds_6.f90   -Os  execution test

Andreas.
diff mbox

Patch

Index: generated/matmul_c10.c
===================================================================
--- generated/matmul_c10.c	(Revision 247566)
+++ generated/matmul_c10.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_c10_avx (gfc_array_c10 * const restrict ret
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_10 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_10 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_c10_avx (gfc_array_c10 * const restrict ret
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_10 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_c10_avx2 (gfc_array_c10 * const restrict re
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_10 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_10 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_c10_avx2 (gfc_array_c10 * const restrict re
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_10 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_c10_avx512f (gfc_array_c10 * const restrict
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_10 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_10 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_c10_avx512f (gfc_array_c10 * const restrict
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_10 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_c10_vanilla (gfc_array_c10 * const restrict
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_10 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_10 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_c10_vanilla (gfc_array_c10 * const restrict
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_10 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_c10 (gfc_array_c10 * const restrict retarra
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_10 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_10 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_c10 (gfc_array_c10 * const restrict retarra
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_10 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: generated/matmul_c16.c
===================================================================
--- generated/matmul_c16.c	(Revision 247566)
+++ generated/matmul_c16.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_c16_avx (gfc_array_c16 * const restrict ret
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_c16_avx (gfc_array_c16 * const restrict ret
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_c16_avx2 (gfc_array_c16 * const restrict re
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_c16_avx2 (gfc_array_c16 * const restrict re
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_c16_avx512f (gfc_array_c16 * const restrict
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_c16_avx512f (gfc_array_c16 * const restrict
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_c16_vanilla (gfc_array_c16 * const restrict
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_c16_vanilla (gfc_array_c16 * const restrict
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_c16 (gfc_array_c16 * const restrict retarra
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_c16 (gfc_array_c16 * const restrict retarra
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: generated/matmul_c4.c
===================================================================
--- generated/matmul_c4.c	(Revision 247566)
+++ generated/matmul_c4.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_c4_avx (gfc_array_c4 * const restrict retar
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_c4_avx (gfc_array_c4 * const restrict retar
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_c4_avx2 (gfc_array_c4 * const restrict reta
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_c4_avx2 (gfc_array_c4 * const restrict reta
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_c4_avx512f (gfc_array_c4 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_c4_avx512f (gfc_array_c4 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_c4_vanilla (gfc_array_c4 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_c4_vanilla (gfc_array_c4 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_c4 (gfc_array_c4 * const restrict retarray,
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_c4 (gfc_array_c4 * const restrict retarray,
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: generated/matmul_c8.c
===================================================================
--- generated/matmul_c8.c	(Revision 247566)
+++ generated/matmul_c8.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_c8_avx (gfc_array_c8 * const restrict retar
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_c8_avx (gfc_array_c8 * const restrict retar
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_c8_avx2 (gfc_array_c8 * const restrict reta
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_c8_avx2 (gfc_array_c8 * const restrict reta
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_c8_avx512f (gfc_array_c8 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_c8_avx512f (gfc_array_c8 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_c8_vanilla (gfc_array_c8 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_c8_vanilla (gfc_array_c8 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_c8 (gfc_array_c8 * const restrict retarray,
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_COMPLEX_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_COMPLEX_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_c8 (gfc_array_c8 * const restrict retarray,
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_COMPLEX_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: generated/matmul_i1.c
===================================================================
--- generated/matmul_i1.c	(Revision 247566)
+++ generated/matmul_i1.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_i1_avx (gfc_array_i1 * const restrict retar
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_1 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_1 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_i1_avx (gfc_array_i1 * const restrict retar
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_1 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_i1_avx2 (gfc_array_i1 * const restrict reta
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_1 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_1 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_i1_avx2 (gfc_array_i1 * const restrict reta
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_1 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_i1_avx512f (gfc_array_i1 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_1 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_1 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_i1_avx512f (gfc_array_i1 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_1 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_i1_vanilla (gfc_array_i1 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_1 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_1 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_i1_vanilla (gfc_array_i1 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_1 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_i1 (gfc_array_i1 * const restrict retarray,
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_1 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_1 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_i1 (gfc_array_i1 * const restrict retarray,
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_1 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: generated/matmul_i16.c
===================================================================
--- generated/matmul_i16.c	(Revision 247566)
+++ generated/matmul_i16.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_i16_avx (gfc_array_i16 * const restrict ret
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_i16_avx (gfc_array_i16 * const restrict ret
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_i16_avx2 (gfc_array_i16 * const restrict re
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_i16_avx2 (gfc_array_i16 * const restrict re
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_i16_avx512f (gfc_array_i16 * const restrict
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_i16_avx512f (gfc_array_i16 * const restrict
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_i16_vanilla (gfc_array_i16 * const restrict
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_i16_vanilla (gfc_array_i16 * const restrict
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_i16 (gfc_array_i16 * const restrict retarra
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_i16 (gfc_array_i16 * const restrict retarra
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: generated/matmul_i2.c
===================================================================
--- generated/matmul_i2.c	(Revision 247566)
+++ generated/matmul_i2.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_i2_avx (gfc_array_i2 * const restrict retar
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_2 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_2 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_i2_avx (gfc_array_i2 * const restrict retar
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_2 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_i2_avx2 (gfc_array_i2 * const restrict reta
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_2 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_2 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_i2_avx2 (gfc_array_i2 * const restrict reta
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_2 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_i2_avx512f (gfc_array_i2 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_2 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_2 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_i2_avx512f (gfc_array_i2 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_2 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_i2_vanilla (gfc_array_i2 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_2 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_2 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_i2_vanilla (gfc_array_i2 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_2 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_i2 (gfc_array_i2 * const restrict retarray,
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_2 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_2 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_i2 (gfc_array_i2 * const restrict retarray,
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_2 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: generated/matmul_i4.c
===================================================================
--- generated/matmul_i4.c	(Revision 247566)
+++ generated/matmul_i4.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_i4_avx (gfc_array_i4 * const restrict retar
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_i4_avx (gfc_array_i4 * const restrict retar
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_i4_avx2 (gfc_array_i4 * const restrict reta
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_i4_avx2 (gfc_array_i4 * const restrict reta
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_i4_avx512f (gfc_array_i4 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_i4_avx512f (gfc_array_i4 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_i4_vanilla (gfc_array_i4 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_i4_vanilla (gfc_array_i4 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_i4 (gfc_array_i4 * const restrict retarray,
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_i4 (gfc_array_i4 * const restrict retarray,
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: generated/matmul_i8.c
===================================================================
--- generated/matmul_i8.c	(Revision 247566)
+++ generated/matmul_i8.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_i8_avx (gfc_array_i8 * const restrict retar
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_i8_avx (gfc_array_i8 * const restrict retar
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_i8_avx2 (gfc_array_i8 * const restrict reta
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_i8_avx2 (gfc_array_i8 * const restrict reta
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_i8_avx512f (gfc_array_i8 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_i8_avx512f (gfc_array_i8 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_i8_vanilla (gfc_array_i8 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_i8_vanilla (gfc_array_i8 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_i8 (gfc_array_i8 * const restrict retarray,
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_INTEGER_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_INTEGER_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_i8 (gfc_array_i8 * const restrict retarray,
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_INTEGER_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: generated/matmul_r10.c
===================================================================
--- generated/matmul_r10.c	(Revision 247566)
+++ generated/matmul_r10.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_r10_avx (gfc_array_r10 * const restrict ret
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_10 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_10 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_r10_avx (gfc_array_r10 * const restrict ret
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_10 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_r10_avx2 (gfc_array_r10 * const restrict re
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_10 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_10 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_r10_avx2 (gfc_array_r10 * const restrict re
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_10 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_r10_avx512f (gfc_array_r10 * const restrict
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_10 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_10 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_r10_avx512f (gfc_array_r10 * const restrict
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_10 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_r10_vanilla (gfc_array_r10 * const restrict
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_10 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_10 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_r10_vanilla (gfc_array_r10 * const restrict
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_10 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_r10 (gfc_array_r10 * const restrict retarra
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_10 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_10 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_r10 (gfc_array_r10 * const restrict retarra
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_10 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: generated/matmul_r16.c
===================================================================
--- generated/matmul_r16.c	(Revision 247566)
+++ generated/matmul_r16.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_r16_avx (gfc_array_r16 * const restrict ret
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_r16_avx (gfc_array_r16 * const restrict ret
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_r16_avx2 (gfc_array_r16 * const restrict re
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_r16_avx2 (gfc_array_r16 * const restrict re
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_r16_avx512f (gfc_array_r16 * const restrict
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_r16_avx512f (gfc_array_r16 * const restrict
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_r16_vanilla (gfc_array_r16 * const restrict
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_r16_vanilla (gfc_array_r16 * const restrict
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_r16 (gfc_array_r16 * const restrict retarra
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_16 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_16 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_r16 (gfc_array_r16 * const restrict retarra
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_16 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: generated/matmul_r4.c
===================================================================
--- generated/matmul_r4.c	(Revision 247566)
+++ generated/matmul_r4.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_r4_avx (gfc_array_r4 * const restrict retar
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_r4_avx (gfc_array_r4 * const restrict retar
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_r4_avx2 (gfc_array_r4 * const restrict reta
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_r4_avx2 (gfc_array_r4 * const restrict reta
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_r4_avx512f (gfc_array_r4 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_r4_avx512f (gfc_array_r4 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_r4_vanilla (gfc_array_r4 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_r4_vanilla (gfc_array_r4 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_r4 (gfc_array_r4 * const restrict retarray,
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_4 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_4 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_r4 (gfc_array_r4 * const restrict retarray,
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_4 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: generated/matmul_r8.c
===================================================================
--- generated/matmul_r8.c	(Revision 247566)
+++ generated/matmul_r8.c	(Arbeitskopie)
@@ -286,8 +286,7 @@  matmul_r8_avx (gfc_array_r8 * const restrict retar
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -311,6 +310,17 @@  matmul_r8_avx (gfc_array_r8 * const restrict retar
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -829,8 +839,7 @@  matmul_r8_avx2 (gfc_array_r8 * const restrict reta
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -854,6 +863,17 @@  matmul_r8_avx2 (gfc_array_r8 * const restrict reta
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1372,8 +1392,7 @@  matmul_r8_avx512f (gfc_array_r8 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1397,6 +1416,17 @@  matmul_r8_avx512f (gfc_array_r8 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -1911,8 +1941,7 @@  matmul_r8_vanilla (gfc_array_r8 * const restrict r
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -1936,6 +1965,17 @@  matmul_r8_vanilla (gfc_array_r8 * const restrict r
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
@@ -2508,8 +2548,7 @@  matmul_r8 (gfc_array_r8 * const restrict retarray,
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      GFC_REAL_8 t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      GFC_REAL_8 f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -2533,6 +2572,17 @@  matmul_r8 (gfc_array_r8 * const restrict retarray,
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      GFC_REAL_8 t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)
Index: m4/matmul_internal.m4
===================================================================
--- m4/matmul_internal.m4	(Revision 247566)
+++ m4/matmul_internal.m4	(Arbeitskopie)
@@ -202,8 +202,7 @@  sinclude(`matmul_asm_'rtype_code`.m4')dnl
 		 i1, i2, i3, i4, i5, i6;
 
       /* Local variables */
-      'rtype_name` t1[65536], /* was [256][256] */
-		 f11, f12, f21, f22, f31, f32, f41, f42,
+      'rtype_name` f11, f12, f21, f22, f31, f32, f41, f42,
 		 f13, f14, f23, f24, f33, f34, f43, f44;
       index_type i, j, l, ii, jj, ll;
       index_type isec, jsec, lsec, uisec, ujsec, ulsec;
@@ -227,6 +226,17 @@  sinclude(`matmul_asm_'rtype_code`.m4')dnl
       if (m == 0 || n == 0 || k == 0)
 	return;
 
+      /* Adjust size of t1 to what is needed.  */
+      index_type t1_dim;
+      t1_dim = (a_dim1-1) * 256 + b_dim1;
+      if (t1_dim > 65536)
+	t1_dim = 65536;
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+      'rtype_name` t1[t1_dim]; /* was [256][256] */
+#pragma GCC diagnostic pop
+
       /* Empty c first.  */
       for (j=1; j<=n; j++)
 	for (i=1; i<=m; i++)