From fd326ba823f7a8cbb2f7c47a2a3d15a8e098a976 Mon Sep 17 00:00:00 2001
From: Ulrich Weigand <uweigand@de.ibm.com>
Date: Thu, 28 Oct 2004 12:47:21 +0000
Subject: [PATCH] re PR target/15286 (ICE cause by reload)

	PR target/15286
	* final.c (alter_subreg): Compute correct offset to use with
	paradoxical SUBREGs of memory operands.
	* recog.c (general_operand): Allow paradoxical SUBREGs of
	memory operands after reload.
	* simplify-rtx.c (simplify_gen_subreg): Fail if simplify_subreg
	has failed when passed a hard register.

From-SVN: r89752
---
 gcc/ChangeLog      | 10 ++++++++++
 gcc/final.c        | 19 ++++++++++++++++++-
 gcc/recog.c        |  6 ++++--
 gcc/simplify-rtx.c |  3 ++-
 4 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4eb71fbc149..e4de1ded60c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2004-10-28  Ulrich Weigand  <uweigand@de.ibm.com>
+
+	PR target/15286
+	* final.c (alter_subreg): Compute correct offset to use with
+	paradoxical SUBREGs of memory operands.
+	* recog.c (general_operand): Allow paradoxical SUBREGs of
+	memory operands after reload.
+	* simplify-rtx.c (simplify_gen_subreg): Fail if simplify_subreg
+	has failed when passed a hard register.
+
 2004-10-28  Aldy Hernandez  <aldyh@redhat.com>
 
 	* function.c (assign_parm_setup_block): Handle parallels correctly.
diff --git a/gcc/final.c b/gcc/final.c
index bf4f521bcf5..3952b9ff82c 100644
--- a/gcc/final.c
+++ b/gcc/final.c
@@ -2608,7 +2608,24 @@ alter_subreg (rtx *xp)
   /* simplify_subreg does not remove subreg from volatile references.
      We are required to.  */
   if (MEM_P (y))
-    *xp = adjust_address (y, GET_MODE (x), SUBREG_BYTE (x));
+    {
+      int offset = SUBREG_BYTE (x);
+
+      /* For paradoxical subregs on big-endian machines, SUBREG_BYTE
+	 contains 0 instead of the proper offset.  See simplify_subreg.  */
+      if (offset == 0
+	  && GET_MODE_SIZE (GET_MODE (y)) < GET_MODE_SIZE (GET_MODE (x)))
+        {
+          int difference = GET_MODE_SIZE (GET_MODE (y))
+			   - GET_MODE_SIZE (GET_MODE (x));
+          if (WORDS_BIG_ENDIAN)
+            offset += (difference / UNITS_PER_WORD) * UNITS_PER_WORD;
+          if (BYTES_BIG_ENDIAN)
+            offset += difference % UNITS_PER_WORD;
+        }
+
+      *xp = adjust_address (y, GET_MODE (x), offset);
+    }
   else
     {
       rtx new = simplify_subreg (GET_MODE (x), y, GET_MODE (y),
diff --git a/gcc/recog.c b/gcc/recog.c
index 61e1186d07a..eeb37afe9bb 100644
--- a/gcc/recog.c
+++ b/gcc/recog.c
@@ -936,8 +936,10 @@ general_operand (rtx op, enum machine_mode mode)
 
 #ifdef INSN_SCHEDULING
       /* On machines that have insn scheduling, we want all memory
-	 reference to be explicit, so outlaw paradoxical SUBREGs.  */
-      if (MEM_P (sub)
+	 reference to be explicit, so outlaw paradoxical SUBREGs.
+	 However, we must allow them after reload so that they can
+	 get cleaned up by cleanup_subreg_operands.  */
+      if (!reload_completed && MEM_P (sub)
 	  && GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (sub)))
 	return 0;
 #endif
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 4af468a40ca..e463fef1efe 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -3789,7 +3789,8 @@ simplify_gen_subreg (enum machine_mode outermode, rtx op,
   if (newx)
     return newx;
 
-  if (GET_CODE (op) == SUBREG || GET_MODE (op) == VOIDmode)
+  if (GET_CODE (op) == SUBREG || GET_MODE (op) == VOIDmode
+      || (REG_P (op) && REGNO (op) < FIRST_PSEUDO_REGISTER))
     return NULL_RTX;
 
   return gen_rtx_SUBREG (outermode, op, byte);