Jeff Law <l...@redhat.com> writes:
> On 01/24/14 01:24, Richard Sandiford wrote:
>> Richard Sandiford <rdsandif...@googlemail.com> writes:
>>> The other problem is related to the way that MIPS16 tests for equality.
>>> Conditional branches test register $24, and the only instructions that
>>> set $24 are MOVE and CMP(I), which is actually an XOR rather than a
>>> subtraction.
>>
>> Er, don't know what I was thinking here, but please ignore this summary
>> of the ISA. There are conditional branches to test MIPS16 registers
>> and other ways of setting $24. (But other than that...)
>>
>> The patch itself still stands though.
> Right. This is just the RTL version of what I did for trees about a
> year ago.
>
> The comment is a bit misleading as far as pulling things out of the RTL.
> You're showing it a combined form. SET is something like
> (set (reg) (xor (reg) (reg))) if I'm reading everything correctly.
>
> Please try to improve the comment and you're good to go. No need to
> wait for further review, but please post the final form for the archivers.
Thanks, here's what I applied.
Richard
gcc/
* rtlanal.c (canonicalize_condition): Split out duplicated mode check.
Handle XOR.
gcc/testsuite/
* gcc.dg/unroll_1.c: Add -fenable-rtl-loop2.
Index: gcc/rtlanal.c
===================================================================
--- gcc/rtlanal.c 2014-01-23 22:27:57.176646235 +0000
+++ gcc/rtlanal.c 2014-01-25 20:00:19.952181804 +0000
@@ -5051,23 +5051,24 @@ canonicalize_condition (rtx insn, rtx co
??? This mode check should perhaps look more like the mode check
in simplify_comparison in combine. */
-
- if ((GET_CODE (SET_SRC (set)) == COMPARE
- || (((code == NE
- || (code == LT
- && val_signbit_known_set_p (inner_mode,
- STORE_FLAG_VALUE))
+ if (((GET_MODE_CLASS (mode) == MODE_CC)
+ != (GET_MODE_CLASS (inner_mode) == MODE_CC))
+ && mode != VOIDmode
+ && inner_mode != VOIDmode)
+ break;
+ if (GET_CODE (SET_SRC (set)) == COMPARE
+ || (((code == NE
+ || (code == LT
+ && val_signbit_known_set_p (inner_mode,
+ STORE_FLAG_VALUE))
#ifdef FLOAT_STORE_FLAG_VALUE
- || (code == LT
- && SCALAR_FLOAT_MODE_P (inner_mode)
- && (fsfv = FLOAT_STORE_FLAG_VALUE (inner_mode),
- REAL_VALUE_NEGATIVE (fsfv)))
+ || (code == LT
+ && SCALAR_FLOAT_MODE_P (inner_mode)
+ && (fsfv = FLOAT_STORE_FLAG_VALUE (inner_mode),
+ REAL_VALUE_NEGATIVE (fsfv)))
#endif
- ))
- && COMPARISON_P (SET_SRC (set))))
- && (((GET_MODE_CLASS (mode) == MODE_CC)
- == (GET_MODE_CLASS (inner_mode) == MODE_CC))
- || mode == VOIDmode || inner_mode == VOIDmode))
+ ))
+ && COMPARISON_P (SET_SRC (set))))
x = SET_SRC (set);
else if (((code == EQ
|| (code == GE
@@ -5080,15 +5081,25 @@ canonicalize_condition (rtx insn, rtx co
REAL_VALUE_NEGATIVE (fsfv)))
#endif
))
- && COMPARISON_P (SET_SRC (set))
- && (((GET_MODE_CLASS (mode) == MODE_CC)
- == (GET_MODE_CLASS (inner_mode) == MODE_CC))
- || mode == VOIDmode || inner_mode == VOIDmode))
-
+ && COMPARISON_P (SET_SRC (set)))
{
reverse_code = 1;
x = SET_SRC (set);
}
+ else if ((code == EQ || code == NE)
+ && GET_CODE (SET_SRC (set)) == XOR)
+ /* Handle sequences like:
+
+ (set op0 (xor X Y))
+ ...(eq|ne op0 (const_int 0))...
+
+ in which case:
+
+ (eq op0 (const_int 0)) reduces to (eq X Y)
+ (ne op0 (const_int 0)) reduces to (ne X Y)
+
+ This is the form used by MIPS16, for example. */
+ x = SET_SRC (set);
else
break;
}
Index: gcc/testsuite/gcc.dg/unroll_1.c
===================================================================
--- gcc/testsuite/gcc.dg/unroll_1.c 2014-01-23 22:27:57.176646235 +0000
+++ gcc/testsuite/gcc.dg/unroll_1.c 2014-01-24 17:52:54.258209196 +0000
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-O2 -fdump-rtl-loop2_unroll=stderr -fno-peel-loops
-fno-tree-vrp -fdisable-tree-cunroll -fdisable-tree-cunrolli
-fenable-rtl-loop2_unroll" } */
+/* { dg-options "-O2 -fdump-rtl-loop2_unroll=stderr -fno-peel-loops
-fno-tree-vrp -fdisable-tree-cunroll -fdisable-tree-cunrolli -fenable-rtl-loop2
-fenable-rtl-loop2_unroll" } */
unsigned a[100], b[100];
inline void bar()
