diff mbox

[8/8] Add a common .md file and define standard constraints there

Message ID 87fvj8ue13.fsf@talisman.default
State New
Headers show

Commit Message

Richard Sandiford June 14, 2014, 7:49 a.m. UTC 
Steve Ellcey <sellcey@mips.com> writes:
> Richard,
>
> Something in these constraint patches broke my mips16 build (I cannot
> build glibc in mips16 mode).  I have cut down a test case and verified
> that the problem started with this checkin:
>
> 2014-06-11  Richard Sandiford  <rdsandiford@googlemail.com>
>
> 	* common.md: New file.
> 	* doc/md.texi: Update description of generic, machine-independent
> 	constraints.
> 	* config/s390/constraints.md (e): Delete.
> 	* Makefile.in (md_file): Include common.md.
> 	* config/m32c/t-m32c (md_file): Likewise.
> 	* genpreds.c (general_mem): New array.
> 	(etc)
>
> Attached is a small test case (its ugly but it comes from vfscanf in glibc) that
> fails to compile for me with these options:
>
>   -mips32r2 -mips16 -mabi=32 -std=gnu99 -fgnu89-inline -O2 -c x.c
>
> Error message:
>
> /tmp/ccAltddb.s: Assembler messages:
> /tmp/ccAltddb.s:23: Error: invalid operands `sb $3,24($sp)'

The problem here is that mips_regno_mode_ok_for_base_p allows invalid
hard registers as bases if !strict_p.  It was always a bit of a hack
and the reason it was added no longer applies.  Robert's LRA patch
already included a fix, so maybe we should just apply that part now.

The patch below fixes the testcase.  Please could you give it a spin
and see whether there's any other fallout?  I assume this would have
shown up in a testsuite run if you'd been able to get that far.

Thanks,
Richard


2014-03-26  Robert Suchanek  <Robert.Suchanek@imgtec.com>

	* config/mips/mips.c (mips_regno_mode_ok_for_base_p): Remove use
	!strict_p for MIPS16.

l

Comments

Steve Ellcey June 16, 2014, 2:48 p.m. UTC | #1 
On Sat, 2014-06-14 at 08:49 +0100, Richard Sandiford wrote:

> The patch below fixes the testcase.  Please could you give it a spin
> and see whether there's any other fallout?  I assume this would have
> shown up in a testsuite run if you'd been able to get that far.
> 
> Thanks,
> Richard

The patch fixed my build and the testsuite results looked good too.

Steve Ellcey
sellcey@mips.com
diff mbox

Patch

diff --git gcc/config/mips/mips.c gcc/config/mips/mips.c
index 45256e9..81b6c26 100644
--- gcc/config/mips/mips.c
+++ gcc/config/mips/mips.c
@@ -2241,22 +2241,9 @@  mips_regno_mode_ok_for_base_p (int regno, enum machine_mode mode,
     return true;
 
   /* In MIPS16 mode, the stack pointer can only address word and doubleword
-     values, nothing smaller.  There are two problems here:
-
-       (a) Instantiating virtual registers can introduce new uses of the
-	   stack pointer.  If these virtual registers are valid addresses,
-	   the stack pointer should be too.
-
-       (b) Most uses of the stack pointer are not made explicit until
-	   FRAME_POINTER_REGNUM and ARG_POINTER_REGNUM have been eliminated.
-	   We don't know until that stage whether we'll be eliminating to the
-	   stack pointer (which needs the restriction) or the hard frame
-	   pointer (which doesn't).
-
-     All in all, it seems more consistent to only enforce this restriction
-     during and after reload.  */
+     values, nothing smaller.  */
   if (TARGET_MIPS16 && regno == STACK_POINTER_REGNUM)
-    return !strict_p || GET_MODE_SIZE (mode) == 4 || GET_MODE_SIZE (mode) == 8;
+    return GET_MODE_SIZE (mode) == 4 || GET_MODE_SIZE (mode) == 8;
 
   return TARGET_MIPS16 ? M16_REG_P (regno) : GP_REG_P (regno);
 }