[backport from gcc-4.8/trunk r191875, dropped inapplicable
 sparc_fold_builtin changes <mikpe@it.uu.se>]

From: Eric Botcazou <ebotcazou at adacore dot com>
Subject: [SPARC] Fix recent and older thinkos
Date: Sun, 30 Sep 2012 19:51:32 +0200
List-Archive: <http://gcc.gnu.org/ml/gcc-patches/>

This fixes a recent thinko introduced by the double-int rewrite and 
responsible for the following failures:

FAIL: gcc.target/sparc/pdist-2.c scan-tree-dump optimized "return 475"
FAIL: gcc.target/sparc/pdist-3.c execution test

as well as an older one spotted by Bernd, whereby the compiler emits non-
canonical RTL for the stack adjustments issued for the epilogue.  The patch 
also contains a patchlet for reorg.c that performs a bit of manual CSE:
 
XVECEXP (PATTERN (insn), 0, 0)  --> delay_insn

and which makes it more obvious why you can take JUMP_LABEL (delay_insn).

Tested on SPARC/Linux, applied on the mainline.

gcc/

2012-09-30  Eric Botcazou  <ebotcazou@adacore.com>

	* reorg.c (relax_delay_slots): Use delay_insn consistently.

	* config/sparc/sparc.c (gen_stack_pointer_dec): Delete.
	(sparc_expand_epilogue): Use gen_stack_pointer_inc and adjust.
	(sparc_flat_expand_epilogue): Likewise.
	(emit_and_preserve): Likewise.

--- gcc-4.7.2/gcc/config/sparc/sparc.c.~1~	2012-09-02 12:36:54.000000000 +0200
+++ gcc-4.7.2/gcc/config/sparc/sparc.c	2012-10-06 14:49:22.000000000 +0200
@@ -4915,18 +4915,6 @@ gen_stack_pointer_inc (rtx increment)
 				    increment));
 }
 
-/* Generate a decrement for the stack pointer.  */
-
-static rtx
-gen_stack_pointer_dec (rtx decrement)
-{
-  return gen_rtx_SET (VOIDmode,
-		      stack_pointer_rtx,
-		      gen_rtx_MINUS (Pmode,
-				     stack_pointer_rtx,
-				     decrement));
-}
-
 /* Expand the function prologue.  The prologue is responsible for reserving
    storage for the frame, saving the call-saved registers and loading the
    GOT register if needed.  */
@@ -5197,17 +5185,17 @@ sparc_expand_epilogue (bool for_eh)
   else if (sparc_leaf_function_p)
     {
       if (size <= 4096)
-	emit_insn (gen_stack_pointer_dec (GEN_INT (-size)));
+	emit_insn (gen_stack_pointer_inc (GEN_INT (size)));
       else if (size <= 8192)
 	{
-	  emit_insn (gen_stack_pointer_dec (GEN_INT (-4096)));
-	  emit_insn (gen_stack_pointer_dec (GEN_INT (4096 - size)));
+	  emit_insn (gen_stack_pointer_inc (GEN_INT (4096)));
+	  emit_insn (gen_stack_pointer_inc (GEN_INT (size - 4096)));
 	}
       else
 	{
 	  rtx reg = gen_rtx_REG (Pmode, 1);
-	  emit_move_insn (reg, GEN_INT (-size));
-	  emit_insn (gen_stack_pointer_dec (reg));
+	  emit_move_insn (reg, GEN_INT (size));
+	  emit_insn (gen_stack_pointer_inc (reg));
 	}
     }
 }
@@ -5257,17 +5245,17 @@ sparc_flat_expand_epilogue (bool for_eh)
       emit_insn (gen_blockage ());
 
       if (size <= 4096)
-	emit_insn (gen_stack_pointer_dec (GEN_INT (-size)));
+	emit_insn (gen_stack_pointer_inc (GEN_INT (size)));
       else if (size <= 8192)
 	{
-	  emit_insn (gen_stack_pointer_dec (GEN_INT (-4096)));
-	  emit_insn (gen_stack_pointer_dec (GEN_INT (4096 - size)));
+	  emit_insn (gen_stack_pointer_inc (GEN_INT (4096)));
+	  emit_insn (gen_stack_pointer_inc (GEN_INT (size - 4096)));
 	}
       else
 	{
 	  rtx reg = gen_rtx_REG (Pmode, 1);
-	  emit_move_insn (reg, GEN_INT (-size));
-	  emit_insn (gen_stack_pointer_dec (reg));
+	  emit_move_insn (reg, GEN_INT (size));
+	  emit_insn (gen_stack_pointer_inc (reg));
 	}
     }
 }
@@ -10414,7 +10402,7 @@ emit_and_preserve (rtx seq, rtx reg, rtx
     = gen_rtx_MEM (word_mode, plus_constant (stack_pointer_rtx,
 					     SPARC_STACK_BIAS + offset));
 
-  emit_insn (gen_stack_pointer_dec (GEN_INT (size)));
+  emit_insn (gen_stack_pointer_inc (GEN_INT (-size)));
   emit_insn (gen_rtx_SET (VOIDmode, slot, reg));
   if (reg2)
     emit_insn (gen_rtx_SET (VOIDmode,
--- gcc-4.7.2/gcc/reorg.c.~1~	2012-02-11 10:00:42.000000000 +0100
+++ gcc-4.7.2/gcc/reorg.c	2012-10-06 14:49:22.000000000 +0200
@@ -3466,9 +3466,8 @@ relax_delay_slots (rtx first)
 	    reorg_redirect_jump (insn, other_target);
 	}
 
-      /* Now look only at cases where we have filled a delay slot.  */
-      if (!NONJUMP_INSN_P (insn)
-	  || GET_CODE (PATTERN (insn)) != SEQUENCE)
+      /* Now look only at cases where we have a filled delay slot.  */
+      if (!NONJUMP_INSN_P (insn) || GET_CODE (PATTERN (insn)) != SEQUENCE)
 	continue;
 
       pat = PATTERN (insn);
@@ -3528,9 +3527,8 @@ relax_delay_slots (rtx first)
 	}
 
       /* Now look only at the cases where we have a filled JUMP_INSN.  */
-      if (!JUMP_P (XVECEXP (PATTERN (insn), 0, 0))
-	  || ! (condjump_p (XVECEXP (PATTERN (insn), 0, 0))
-		|| condjump_in_parallel_p (XVECEXP (PATTERN (insn), 0, 0))))
+      if (!JUMP_P (delay_insn)
+	  || !(condjump_p (delay_insn) || condjump_in_parallel_p (delay_insn)))
 	continue;
 
       target_label = JUMP_LABEL (delay_insn);