gcc/gcc48-pr56151.patch

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2013-02-11 21:40:42 +00:00
2013-02-11 Jakub Jelinek <jakub@redhat.com>
Steven Bosscher <steven@gcc.gnu.org>
PR rtl-optimization/56151
* optabs.c (add_equal_note): Don't return 0 if target is a MEM,
equal to op0 or op1, and last_insn pattern is CODE operation
with MEM dest and one of the operands matches that MEM.
* gcc.target/i386/pr56151.c: New test.
--- gcc/optabs.c.jj 2013-01-16 08:30:10.000000000 +0100
+++ gcc/optabs.c 2013-02-11 15:28:16.543839881 +0100
@@ -190,17 +190,34 @@ add_equal_note (rtx insns, rtx target, e
if (GET_CODE (target) == ZERO_EXTRACT)
return 1;
- /* If TARGET is in OP0 or OP1, punt. We'd end up with a note referencing
- a value changing in the insn, so the note would be invalid for CSE. */
- if (reg_overlap_mentioned_p (target, op0)
- || (op1 && reg_overlap_mentioned_p (target, op1)))
- return 0;
-
for (last_insn = insns;
NEXT_INSN (last_insn) != NULL_RTX;
last_insn = NEXT_INSN (last_insn))
;
+ /* If TARGET is in OP0 or OP1, punt. We'd end up with a note referencing
+ a value changing in the insn, so the note would be invalid for CSE. */
+ if (reg_overlap_mentioned_p (target, op0)
+ || (op1 && reg_overlap_mentioned_p (target, op1)))
+ {
+ if (MEM_P (target)
+ && (rtx_equal_p (target, op0)
+ || (op1 && rtx_equal_p (target, op1))))
+ {
+ /* For MEM target, with MEM = MEM op X, prefer no REG_EQUAL note
+ over expanding it as temp = MEM op X, MEM = temp. See PR56151. */
+ set = single_set (last_insn);
+ if (set
+ && GET_CODE (SET_SRC (set)) == code
+ && MEM_P (SET_DEST (set))
+ && (rtx_equal_p (SET_DEST (set), XEXP (SET_SRC (set), 0))
+ || (op1 && rtx_equal_p (SET_DEST (set),
+ XEXP (SET_SRC (set), 1)))))
+ return 1;
+ }
+ return 0;
+ }
+
set = single_set (last_insn);
if (set == NULL_RTX)
return 1;
--- gcc/testsuite/gcc.target/i386/pr56151.c.jj 2013-02-11 16:20:51.459752951 +0100
+++ gcc/testsuite/gcc.target/i386/pr56151.c 2013-02-11 16:23:10.590964710 +0100
@@ -0,0 +1,17 @@
+/* PR rtl-optimization/56151 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+int vara, varb;
+
+void
+foo (int i, int j)
+{
+ vara = varb | vara;
+}
+
+/* Verify the above is compiled into movl varb, %reg; orl %reg, vara instead
+ of longer movl vara, %reg; orl varb, %reg; movl %reg, vara. */
+/* { dg-final { scan-assembler-not "mov\[^\n\r]*vara" { target nonpic } } } */
+/* { dg-final { scan-assembler-times "mov\[^\n\r]*varb" 1 { target nonpic } } } */
+/* { dg-final { scan-assembler-times "or\[^\n\r]*vara" 1 { target nonpic } } } */