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Re: [PATCH] Fix PR optimization/6822
- From: Richard Henderson <rth at redhat dot com>
- To: Eric Botcazou <ebotcazou at libertysurf dot fr>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Thu, 30 May 2002 16:14:19 -0700
- Subject: Re: [PATCH] Fix PR optimization/6822
- References: <029701c2081f$844c5a80$f60c81d4@zephyr>
On Thu, May 30, 2002 at 11:16:03PM +0200, Eric Botcazou wrote:
> * config/i386/i386.c (ix86_expand_int_movcc): When trying to convert
> a LEU or a GTU, use GET_MODE_MASK to check the second operand. Use
> get_int_mode to truncate it to the right mode after incrementing it.
I actually lied to you about using GET_MODE_MASK. We're interested
in the maximum value for a mode, and since constants are always sign
extended, this is always -1.
The revised patch that I applied is attached.
> Should the testcase go in torture/compile, or dg to restrict it to i386 ?
Nothing x86 specific about it. Therefore we run it everywhere.
Installed as compile/20020530-1.c.
> pushl %ebp
> movl %esp, %ebp
> pushl %eax
> pushl %eax
> call foo1
[...]
> The ifcvt pass has devised a clever way to eliminate the conditional jump,
> but it looks like the two stack slots thus freed haven't been deleted.
That's actually stack alignment for the call to foo.
r~
* config/i386/i386.c (ix86_expand_int_movcc): Don't cast INTVAL
to unsigned int for op1 comparisons. Use gen_int_mode.
Index: i386.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/i386/i386.c,v
retrieving revision 1.368.2.12
diff -c -p -d -r1.368.2.12 i386.c
*** i386.c 29 May 2002 20:34:21 -0000 1.368.2.12
--- i386.c 30 May 2002 23:02:09 -0000
*************** ix86_expand_int_movcc (operands)
*** 7963,7973 ****
if ((code == LEU || code == GTU)
&& GET_CODE (ix86_compare_op1) == CONST_INT
&& mode != HImode
! && (unsigned int) INTVAL (ix86_compare_op1) != 0xffffffff
! /* The operand still must be representable as sign extended value. */
&& (!TARGET_64BIT
|| GET_MODE (ix86_compare_op0) != DImode
! || (unsigned int) INTVAL (ix86_compare_op1) != 0x7fffffff)
&& GET_CODE (operands[2]) == CONST_INT
&& GET_CODE (operands[3]) == CONST_INT)
{
--- 7963,7974 ----
if ((code == LEU || code == GTU)
&& GET_CODE (ix86_compare_op1) == CONST_INT
&& mode != HImode
! && INTVAL (ix86_compare_op1) != -1
! /* For x86-64, the immediate field in the instruction is 32-bit
! signed, so we can't increment a DImode value above 0x7fffffff. */
&& (!TARGET_64BIT
|| GET_MODE (ix86_compare_op0) != DImode
! || INTVAL (ix86_compare_op1) != 0x7fffffff)
&& GET_CODE (operands[2]) == CONST_INT
&& GET_CODE (operands[3]) == CONST_INT)
{
*************** ix86_expand_int_movcc (operands)
*** 7975,7981 ****
code = LTU;
else
code = GEU;
! ix86_compare_op1 = GEN_INT (INTVAL (ix86_compare_op1) + 1);
}
start_sequence ();
--- 7976,7983 ----
code = LTU;
else
code = GEU;
! ix86_compare_op1 = gen_int_mode (INTVAL (ix86_compare_op1) + 1,
! GET_MODE (ix86_compare_op0));
}
start_sequence ();