Steve Ellcey <sell...@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 <rdsandif...@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.sucha...@imgtec.com>
* config/mips/mips.c (mips_regno_mode_ok_for_base_p): Remove use
!strict_p for MIPS16.
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);
}
l
