re PR rtl-optimization/24257 (ICE: in extract_insn with -O -fgcse -fgcse-sm)

2006-01-14  Steven Bosscher  <stevenb.gcc@gmail.com>
	Richard Guenther  <rguenther@suse.de>

	PR rtl-optimization/24257
	* gcse.c (find_moveable_store): Only consider a store movable
	when the SET_SRC of the insn can be assigned to a register.

	* gcc.dg/torture/pr24257.c: New testcase.

Co-Authored-By: Richard Guenther <rguenther@suse.de>

From-SVN: r109701

gcc/ChangeLog

+2006-01-14  Steven Bosscher  <stevenb.gcc@gmail.com>
+	Richard Guenther  <rguenther@suse.de>
+
+	PR rtl-optimization/24257
+	* gcse.c (find_moveable_store): Only consider a store movable
+	when the SET_SRC of the insn can be assigned to a register.
+
 2006-01-14  Ian Lance Taylor  <ian@airs.com>
 
 	* tree.c (tree_not_class_check_failed): New function.

gcc/gcse.c

@@ -5664,6 +5664,14 @@ find_moveable_store (rtx insn, int *regs_set_before, int *regs_set_after)
   if (find_reg_note (insn, REG_EH_REGION, NULL_RTX))
     return;
 
+  /* Make sure that the SET_SRC of this store insns can be assigned to
+     a register, or we will fail later on in replace_store_insn, which
+     assumes that we can do this.  But sometimes the target machine has
+     oddities like MEM read-modify-write instruction.  See for example
+     PR24257.  */
+  if (!can_assign_to_reg_p (SET_SRC (set)))
+    return;
+
   ptr = ldst_entry (dest);
   if (!ptr->pattern_regs)
     ptr->pattern_regs = extract_mentioned_regs (dest);

gcc/testsuite/ChangeLog

+2006-01-14  Steven Bosscher  <stevenb.gcc@gmail.com>
+	Richard Guenther  <rguenther@suse.de>
+
+	PR rtl-optimization/24257
+	* gcc.dg/torture/pr24257.c: New testcase.
+
 2006-01-13  Adam Nemet  <anemet@caviumnetworks.com>
 
 	* gcc.c-torture/execute/20060110-1.c: New test.

gcc/testsuite/gcc.dg/torture/pr24257.c

+/* { dg-do compile } */
+/* { dg-options "-O -fgcse -fgcse-sm" } */
+
+typedef struct A {
+    int buf, left;
+} A;
+
+static void flush(A *s, int n)
+{
+    s->buf <<= n;
+
+    while (s->left < 32) {
+        s->buf <<= 8;
+        s->left += 8;
+    }
+
+    s->buf=0;
+}
+
+void oof(A *s, int n)
+{
+    s->buf = n;
+    s->left = n;
+
+    flush(s, n);
+}