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.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@109701 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0e8ee82..e7961fe 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+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.

diff --git a/gcc/gcse.c b/gcc/gcse.c
index 5966694..290f70e 100644 (file)
--- a/gcc/gcse.c
+++ b/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);

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index cca26ea..66a7b7f 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+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.

diff --git a/gcc/testsuite/gcc.dg/torture/pr24257.c b/gcc/testsuite/gcc.dg/torture/pr24257.c
new file mode 100644 (file)
index 0000000..200bd18
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr24257.c
@@ -0,0 +1,26 @@
+/* { 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);
+}