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[PATCH] m68k: add missing early clobber in beq0_di, bne0_di patterns


This is a wrong code bug that appeared in netcdf when compiling with gcc
4.8.  Due to difference in register allocation this doesn't trigger in
4.9 or trunk, but it is obvious that the bug is only dormant.  The issue
is that if the first operand matches "o" it may contain the same
register as operand 2 as part of the address.  Clearly the register
overlap checks only make sense if the first operand matches "d".  So for
an "o" operand we need to mark the scratch register as early clobber.

Bootstrapped on m68k-suse-linux and installed in trunk.

Andreas.

	* config/m68k/m68k.md (beq0_di, bne0_di): Make the "o" constraint
	a separate alternative where the scratch operand 2 is marked as
	early clobber.
---
 gcc/config/m68k/m68k.md | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/gcc/config/m68k/m68k.md b/gcc/config/m68k/m68k.md
index c4ebb0e..9729624 100644
--- a/gcc/config/m68k/m68k.md
+++ b/gcc/config/m68k/m68k.md
@@ -5961,15 +5961,15 @@
 
 (define_insn "beq0_di"
   [(set (pc)
-    (if_then_else (eq (match_operand:DI 0 "general_operand" "d*ao,<>")
+    (if_then_else (eq (match_operand:DI 0 "general_operand" "d*a,o,<>")
             (const_int 0))
-        (label_ref (match_operand 1 "" ","))
+        (label_ref (match_operand 1 "" ",,"))
         (pc)))
-   (clobber (match_scratch:SI 2 "=d,d"))]
+   (clobber (match_scratch:SI 2 "=d,&d,d"))]
   ""
 {
   CC_STATUS_INIT;
-  if (which_alternative == 1)
+  if (which_alternative == 2)
     return "move%.l %0,%2\;or%.l %0,%2\;jeq %l1";
   if ((cc_prev_status.value1
       && rtx_equal_p (cc_prev_status.value1, operands[0]))
@@ -6006,11 +6006,11 @@
 
 (define_insn "bne0_di"
   [(set (pc)
-    (if_then_else (ne (match_operand:DI 0 "general_operand" "do,*a")
+    (if_then_else (ne (match_operand:DI 0 "general_operand" "d,o,*a")
             (const_int 0))
-        (label_ref (match_operand 1 "" ","))
+        (label_ref (match_operand 1 "" ",,"))
         (pc)))
-   (clobber (match_scratch:SI 2 "=d,X"))]
+   (clobber (match_scratch:SI 2 "=d,&d,X"))]
   ""
 {
   if ((cc_prev_status.value1
-- 
2.0.0

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."


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