./:

	PR rtl-optimization/24883
	* combine.c (combinable_i3pat): When checking whether the
	destination of i3 is used in i3, consider paradoxical subregs.
testsuite/:
	PR rtl-optimization/24883
	* gcc.c-torture/compile/pr24883.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@107279 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 51 insertions, 10 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5f1e761a4ad..630bebc1bbf 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2005-11-20  Ian Lance Taylor  <ian@airs.com>
+
+	PR rtl-optimization/24883
+	* combine.c (combinable_i3pat): When checking whether the
+	destination of i3 is used in i3, consider paradoxical subregs.
+
 2005-11-21  Kazu Hirata  <kazu@codesourcery.com>
 
 	PR middle-end/20583
diff --git a/gcc/combine.c b/gcc/combine.c
index 6497336bf44..abd64582d3e 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -1423,6 +1423,7 @@ combinable_i3pat (rtx i3, rtx *loc, rtx i2dest, rtx i1dest,
       rtx dest = SET_DEST (set);
       rtx src = SET_SRC (set);
       rtx inner_dest = dest;
+      rtx subdest;
 
       while (GET_CODE (inner_dest) == STRICT_LOW_PART
 	     || GET_CODE (inner_dest) == SUBREG
@@ -1457,27 +1458,35 @@ combinable_i3pat (rtx i3, rtx *loc, rtx i2dest, rtx i1dest,
 	  || (i1_not_in_src && reg_overlap_mentioned_p (i1dest, src)))
 	return 0;
 
-      /* If DEST is used in I3, it is being killed in this insn,
-	 so record that for later.
+      /* If DEST is used in I3, it is being killed in this insn, so
+	 record that for later.  We have to consider paradoxical
+	 subregs here, since they kill the whole register, but we
+	 ignore partial subregs, STRICT_LOW_PART, etc.
 	 Never add REG_DEAD notes for the FRAME_POINTER_REGNUM or the
 	 STACK_POINTER_REGNUM, since these are always considered to be
 	 live.  Similarly for ARG_POINTER_REGNUM if it is fixed.  */
-      if (pi3dest_killed && REG_P (dest)
-	  && reg_referenced_p (dest, PATTERN (i3))
-	  && REGNO (dest) != FRAME_POINTER_REGNUM
+      subdest = dest;
+      if (GET_CODE (subdest) == SUBREG
+	  && (GET_MODE_SIZE (GET_MODE (subdest))
+	      >= GET_MODE_SIZE (GET_MODE (SUBREG_REG (subdest)))))
+	subdest = SUBREG_REG (subdest);
+      if (pi3dest_killed
+	  && REG_P (subdest)
+	  && reg_referenced_p (subdest, PATTERN (i3))
+	  && REGNO (subdest) != FRAME_POINTER_REGNUM
 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
-	  && REGNO (dest) != HARD_FRAME_POINTER_REGNUM
+	  && REGNO (subdest) != HARD_FRAME_POINTER_REGNUM
 #endif
 #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM
-	  && (REGNO (dest) != ARG_POINTER_REGNUM
-	      || ! fixed_regs [REGNO (dest)])
+	  && (REGNO (subdest) != ARG_POINTER_REGNUM
+	      || ! fixed_regs [REGNO (subdest)])
 #endif
-	  && REGNO (dest) != STACK_POINTER_REGNUM)
+	  && REGNO (subdest) != STACK_POINTER_REGNUM)
 	{
 	  if (*pi3dest_killed)
 	    return 0;
 
-	  *pi3dest_killed = dest;
+	  *pi3dest_killed = subdest;
 	}
     }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 48f03546b5f..1a05c183fec 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2005-11-20  Ian Lance Taylor  <ian@airs.com>
+
+	PR rtl-optimization/24883
+	* gcc.c-torture/compile/pr24883.c: New test.
+
 2005-11-21  Kazu Hirata  <kazu@codesourcery.com>
 
 	PR middle-end/20583
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr24883.c b/gcc/testsuite/gcc.c-torture/compile/pr24883.c
new file mode 100644
index 00000000000..b2ced75ac96
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr24883.c
@@ -0,0 +1,21 @@
+typedef struct _rec_stl rec_stl;
+struct _rec_stl {
+   unsigned char **strs;
+};
+orec_str_list(int count) {
+   rec_stl *stl;
+   int i, j;
+   int li, lj;
+   unsigned char ci, cj;
+   for (i = 0; i < count; i++) {
+      for (j = i + 1; j < count; j++) {
+         cj = lj > 2 ? stl->strs[j][0] : (long)stl->strs[j] & 0xff;
+         if ((count >= 16 && cj < ci) || (cj == ci && lj > li)) {
+            stl->strs[j] = stl->strs[i];
+            ci ^= cj;
+            cj ^= ci;
+            ci ^= cj;
+         }
+      }
+   }
+}