diff mbox series

rtlanal: Another fix for VOIDmode MEMs [PR98601]

Message ID 20210410060757.GI1179226@tucnak
State New
Headers show
Series rtlanal: Another fix for VOIDmode MEMs [PR98601] | expand

Commit Message

Jakub Jelinek April 10, 2021, 6:07 a.m. UTC 
Hi!

This is a sequel to the PR85022 changes, inline-asm can (unfortunately)
introduce VOIDmode MEMs and in PR85022 they have been changed so that
we don't pretend we know their size (as opposed to assuming they have
zero size).

This time we ICE in rtx_addr_can_trap_p_1 because it assumes that
all memory but BLKmode has known size.  The patch just treats VOIDmode
MEMs like BLKmode in that regard.  And, the STRICT_ALIGNMENT change
is needed because VOIDmode has GET_MODE_SIZE of 0 and we don't want to
check if something is a multiple of 0.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2021-04-10  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/98601
	* rtlanal.c (rtx_addr_can_trap_p_1): Allow in assert unknown size
	not just for BLKmode, but also for VOIDmode.  For STRICT_ALIGNMENT
	unaligned_mems handle VOIDmode like BLKmode.

	* gcc.dg/torture/pr98601.c: New test.


	Jakub

Comments

Richard Sandiford April 10, 2021, 9:11 a.m. UTC | #1 
Jakub Jelinek via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
> Hi!
>
> This is a sequel to the PR85022 changes, inline-asm can (unfortunately)
> introduce VOIDmode MEMs and in PR85022 they have been changed so that
> we don't pretend we know their size (as opposed to assuming they have
> zero size).
>
> This time we ICE in rtx_addr_can_trap_p_1 because it assumes that
> all memory but BLKmode has known size.  The patch just treats VOIDmode
> MEMs like BLKmode in that regard.  And, the STRICT_ALIGNMENT change
> is needed because VOIDmode has GET_MODE_SIZE of 0 and we don't want to
> check if something is a multiple of 0.

Sorry if this is reopening an old discussion, but could we instead
canonicalise these MEMs to BLKmode when expanding the inline asm?
I think quite a lot of RTL code assumes that MEMs can be VOIDmode,
so I'd be surprised if these two patches are enough.

Thanks,
Richard

>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2021-04-10  Jakub Jelinek  <jakub@redhat.com>
>
> 	PR rtl-optimization/98601
> 	* rtlanal.c (rtx_addr_can_trap_p_1): Allow in assert unknown size
> 	not just for BLKmode, but also for VOIDmode.  For STRICT_ALIGNMENT
> 	unaligned_mems handle VOIDmode like BLKmode.
>
> 	* gcc.dg/torture/pr98601.c: New test.
>
> --- gcc/rtlanal.c.jj	2021-03-05 21:51:48.689185518 +0100
> +++ gcc/rtlanal.c	2021-04-09 11:15:20.341906331 +0200
> @@ -464,12 +464,17 @@ rtx_addr_can_trap_p_1 (const_rtx x, poly
>  		       machine_mode mode, bool unaligned_mems)
>  {
>    enum rtx_code code = GET_CODE (x);
> -  gcc_checking_assert (mode == BLKmode || known_size_p (size));
> +  gcc_checking_assert (mode == BLKmode
> +		       || mode == VOIDmode
> +		       || known_size_p (size));
>    poly_int64 const_x1;
>  
>    /* The offset must be a multiple of the mode size if we are considering
>       unaligned memory references on strict alignment machines.  */
> -  if (STRICT_ALIGNMENT && unaligned_mems && mode != BLKmode)
> +  if (STRICT_ALIGNMENT
> +      && unaligned_mems
> +      && mode != BLKmode
> +      && mode != VOIDmode)
>      {
>        poly_int64 actual_offset = offset;
>  
> --- gcc/testsuite/gcc.dg/torture/pr98601.c.jj	2021-04-09 11:18:26.964817854 +0200
> +++ gcc/testsuite/gcc.dg/torture/pr98601.c	2021-04-09 11:18:16.758932053 +0200
> @@ -0,0 +1,14 @@
> +/* PR rtl-optimization/98601 */
> +/* { dg-do compile } */
> +
> +void
> +foo (void *p)
> +{
> +  asm ("" : "=m" (*p));			/* { dg-warning "dereferencing 'void \\*' pointer" } */
> +}
> +
> +void
> +bar (void *p)
> +{
> +  asm volatile ("" : : "m" (*p));	/* { dg-warning "dereferencing 'void \\*' pointer" } */
> +}
>
> 	Jakub
Richard Sandiford April 10, 2021, 9:14 a.m. UTC | #2 
Richard Sandiford via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
> Jakub Jelinek via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
>> Hi!
>>
>> This is a sequel to the PR85022 changes, inline-asm can (unfortunately)
>> introduce VOIDmode MEMs and in PR85022 they have been changed so that
>> we don't pretend we know their size (as opposed to assuming they have
>> zero size).
>>
>> This time we ICE in rtx_addr_can_trap_p_1 because it assumes that
>> all memory but BLKmode has known size.  The patch just treats VOIDmode
>> MEMs like BLKmode in that regard.  And, the STRICT_ALIGNMENT change
>> is needed because VOIDmode has GET_MODE_SIZE of 0 and we don't want to
>> check if something is a multiple of 0.
>
> Sorry if this is reopening an old discussion, but could we instead
> canonicalise these MEMs to BLKmode when expanding the inline asm?
> I think quite a lot of RTL code assumes that MEMs can be VOIDmode,

...I meant “can't” of course

> so I'd be surprised if these two patches are enough.
>
> Thanks,
> Richard
>
>>
>> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>>
>> 2021-04-10  Jakub Jelinek  <jakub@redhat.com>
>>
>> 	PR rtl-optimization/98601
>> 	* rtlanal.c (rtx_addr_can_trap_p_1): Allow in assert unknown size
>> 	not just for BLKmode, but also for VOIDmode.  For STRICT_ALIGNMENT
>> 	unaligned_mems handle VOIDmode like BLKmode.
>>
>> 	* gcc.dg/torture/pr98601.c: New test.
>>
>> --- gcc/rtlanal.c.jj	2021-03-05 21:51:48.689185518 +0100
>> +++ gcc/rtlanal.c	2021-04-09 11:15:20.341906331 +0200
>> @@ -464,12 +464,17 @@ rtx_addr_can_trap_p_1 (const_rtx x, poly
>>  		       machine_mode mode, bool unaligned_mems)
>>  {
>>    enum rtx_code code = GET_CODE (x);
>> -  gcc_checking_assert (mode == BLKmode || known_size_p (size));
>> +  gcc_checking_assert (mode == BLKmode
>> +		       || mode == VOIDmode
>> +		       || known_size_p (size));
>>    poly_int64 const_x1;
>>  
>>    /* The offset must be a multiple of the mode size if we are considering
>>       unaligned memory references on strict alignment machines.  */
>> -  if (STRICT_ALIGNMENT && unaligned_mems && mode != BLKmode)
>> +  if (STRICT_ALIGNMENT
>> +      && unaligned_mems
>> +      && mode != BLKmode
>> +      && mode != VOIDmode)
>>      {
>>        poly_int64 actual_offset = offset;
>>  
>> --- gcc/testsuite/gcc.dg/torture/pr98601.c.jj	2021-04-09 11:18:26.964817854 +0200
>> +++ gcc/testsuite/gcc.dg/torture/pr98601.c	2021-04-09 11:18:16.758932053 +0200
>> @@ -0,0 +1,14 @@
>> +/* PR rtl-optimization/98601 */
>> +/* { dg-do compile } */
>> +
>> +void
>> +foo (void *p)
>> +{
>> +  asm ("" : "=m" (*p));			/* { dg-warning "dereferencing 'void \\*' pointer" } */
>> +}
>> +
>> +void
>> +bar (void *p)
>> +{
>> +  asm volatile ("" : : "m" (*p));	/* { dg-warning "dereferencing 'void \\*' pointer" } */
>> +}
>>
>> 	Jakub
Richard Biener April 10, 2021, 10:39 a.m. UTC | #3 
On April 10, 2021 8:07:57 AM GMT+02:00, Jakub Jelinek <jakub@redhat.com> wrote:
>Hi!
>
>This is a sequel to the PR85022 changes, inline-asm can (unfortunately)
>introduce VOIDmode MEMs and in PR85022 they have been changed so that
>we don't pretend we know their size (as opposed to assuming they have
>zero size).
>
>This time we ICE in rtx_addr_can_trap_p_1 because it assumes that
>all memory but BLKmode has known size.  The patch just treats VOIDmode
>MEMs like BLKmode in that regard.  And, the STRICT_ALIGNMENT change
>is needed because VOIDmode has GET_MODE_SIZE of 0 and we don't want to
>check if something is a multiple of 0.
>
>Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Ok. 

We can experiment with differnt canonicalization in GCC 12.

Richard. 

>2021-04-10  Jakub Jelinek  <jakub@redhat.com>
>
>	PR rtl-optimization/98601
>	* rtlanal.c (rtx_addr_can_trap_p_1): Allow in assert unknown size
>	not just for BLKmode, but also for VOIDmode.  For STRICT_ALIGNMENT
>	unaligned_mems handle VOIDmode like BLKmode.
>
>	* gcc.dg/torture/pr98601.c: New test.
>
>--- gcc/rtlanal.c.jj	2021-03-05 21:51:48.689185518 +0100
>+++ gcc/rtlanal.c	2021-04-09 11:15:20.341906331 +0200
>@@ -464,12 +464,17 @@ rtx_addr_can_trap_p_1 (const_rtx x, poly
> 		       machine_mode mode, bool unaligned_mems)
> {
>   enum rtx_code code = GET_CODE (x);
>-  gcc_checking_assert (mode == BLKmode || known_size_p (size));
>+  gcc_checking_assert (mode == BLKmode
>+		       || mode == VOIDmode
>+		       || known_size_p (size));
>   poly_int64 const_x1;
> 
>/* The offset must be a multiple of the mode size if we are considering
>      unaligned memory references on strict alignment machines.  */
>-  if (STRICT_ALIGNMENT && unaligned_mems && mode != BLKmode)
>+  if (STRICT_ALIGNMENT
>+      && unaligned_mems
>+      && mode != BLKmode
>+      && mode != VOIDmode)
>     {
>       poly_int64 actual_offset = offset;
> 
>--- gcc/testsuite/gcc.dg/torture/pr98601.c.jj	2021-04-09
>11:18:26.964817854 +0200
>+++ gcc/testsuite/gcc.dg/torture/pr98601.c	2021-04-09
>11:18:16.758932053 +0200
>@@ -0,0 +1,14 @@
>+/* PR rtl-optimization/98601 */
>+/* { dg-do compile } */
>+
>+void
>+foo (void *p)
>+{
>+  asm ("" : "=m" (*p));			/* { dg-warning "dereferencing 'void \\*'
>pointer" } */
>+}
>+
>+void
>+bar (void *p)
>+{
>+  asm volatile ("" : : "m" (*p));	/* { dg-warning "dereferencing 'void
>\\*' pointer" } */
>+}
>
>	Jakub
diff mbox series

Patch

--- gcc/rtlanal.c.jj	2021-03-05 21:51:48.689185518 +0100
+++ gcc/rtlanal.c	2021-04-09 11:15:20.341906331 +0200
@@ -464,12 +464,17 @@  rtx_addr_can_trap_p_1 (const_rtx x, poly
 		       machine_mode mode, bool unaligned_mems)
 {
   enum rtx_code code = GET_CODE (x);
-  gcc_checking_assert (mode == BLKmode || known_size_p (size));
+  gcc_checking_assert (mode == BLKmode
+		       || mode == VOIDmode
+		       || known_size_p (size));
   poly_int64 const_x1;
 
   /* The offset must be a multiple of the mode size if we are considering
      unaligned memory references on strict alignment machines.  */
-  if (STRICT_ALIGNMENT && unaligned_mems && mode != BLKmode)
+  if (STRICT_ALIGNMENT
+      && unaligned_mems
+      && mode != BLKmode
+      && mode != VOIDmode)
     {
       poly_int64 actual_offset = offset;
 
--- gcc/testsuite/gcc.dg/torture/pr98601.c.jj	2021-04-09 11:18:26.964817854 +0200
+++ gcc/testsuite/gcc.dg/torture/pr98601.c	2021-04-09 11:18:16.758932053 +0200
@@ -0,0 +1,14 @@ 
+/* PR rtl-optimization/98601 */
+/* { dg-do compile } */
+
+void
+foo (void *p)
+{
+  asm ("" : "=m" (*p));			/* { dg-warning "dereferencing 'void \\*' pointer" } */
+}
+
+void
+bar (void *p)
+{
+  asm volatile ("" : : "m" (*p));	/* { dg-warning "dereferencing 'void \\*' pointer" } */
+}