reload1.c (eliminate_regs, case MINUS): Canonicalize (minus (plus reg const) reg) to (plus (minus reg reg) const).

	* reload1.c (eliminate_regs, case MINUS): Canonicalize
	(minus (plus reg const) reg) to (plus (minus reg reg) const).
	* reload.c (find_reloads_address): Treat (plus (minus reg reg) const)
	the same as (plus (plus reg reg) const).

From-SVN: r13539

2 files changed, 32 insertions, 5 deletions

diff --git a/gcc/reload.c b/gcc/reload.c
index 5bb39dc..e1f5f91 100644
--- a/gcc/reload.c
+++ b/gcc/reload.c
@@ -4368,7 +4368,9 @@ find_reloads_address (mode, memrefloc, ad, loc, opnum, type, ind_levels)
   /* If we have an indexed stack slot, there are three possible reasons why
      it might be invalid: The index might need to be reloaded, the address
      might have been made by frame pointer elimination and hence have a
-     constant out of range, or both reasons might apply.  
+     constant out of range, or the address is the result of register
+     elimination and (plus (plus reg reg) const), which has been
+     canonicalized from (plus (plus reg const) reg), isn't a valid address.
 
      We can easily check for an index needing reload, but even if that is the
      case, we might also have an invalid constant.  To avoid making the
@@ -4395,7 +4397,11 @@ find_reloads_address (mode, memrefloc, ad, loc, opnum, type, ind_levels)
      innermost PLUS.  */
 
   else if (GET_CODE (ad) == PLUS && GET_CODE (XEXP (ad, 1)) == CONST_INT
-	   && GET_CODE (XEXP (ad, 0)) == PLUS
+	   && (GET_CODE (XEXP (ad, 0)) == PLUS
+	       /* MINUS can happen as a result of register elimination of
+		  (minus eliminable reg) which gets canonicalized as
+		  (plus (minus reg reg) const).  */
+	       || GET_CODE (XEXP (ad, 0)) == MINUS)
 	   && (XEXP (XEXP (ad, 0), 0) == frame_pointer_rtx
 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
 	       || XEXP (XEXP (ad, 0), 0) == hard_frame_pointer_rtx
@@ -4406,7 +4412,7 @@ find_reloads_address (mode, memrefloc, ad, loc, opnum, type, ind_levels)
 	       || XEXP (XEXP (ad, 0), 0) == stack_pointer_rtx)
 	   && ! memory_address_p (mode, ad))
     {
-      *loc = ad = gen_rtx (PLUS, GET_MODE (ad),
+      *loc = ad = gen_rtx (GET_CODE (XEXP (ad, 0)), GET_MODE (ad),
 			   plus_constant (XEXP (XEXP (ad, 0), 0),
 					  INTVAL (XEXP (ad, 1))),
 			   XEXP (XEXP (ad, 0), 1));
diff --git a/gcc/reload1.c b/gcc/reload1.c
index b5e9394..d4f2140 100644
--- a/gcc/reload1.c
+++ b/gcc/reload1.c
@@ -2853,7 +2853,7 @@ eliminate_regs (x, mem_mode, insn)
 	 context.
 
 	 If we have (plus (eliminable) (reg)), we want to produce
-	 (plus (plus (replacement) (reg) (const))).  If this was part of a
+	 (plus (plus (replacement) (reg)) (const)).  If this was part of a
 	 normal add insn, (plus (replacement) (reg)) will be pushed as a
 	 reload.  This is the desired action.  */
 
@@ -2892,6 +2892,28 @@ eliminate_regs (x, mem_mode, insn)
       }
       return x;
 
+    case MINUS:
+      /* If we have (minus (eliminable) (reg)), we want to produce
+	 (plus (minus (replacement) (reg)) (const)).  The main reason being
+	 to be consistent with what is done for PLUS.  find_reloads_address
+	 assumes that we do this.  */
+      {
+	rtx new0 = eliminate_regs (XEXP (x, 0), mem_mode, insn);
+	rtx new1 = eliminate_regs (XEXP (x, 1), mem_mode, insn);
+
+	if (new0 != XEXP (x, 0) || new1 != XEXP (x, 1))
+	  {
+	    if (GET_CODE (new0) == PLUS)
+	      return gen_rtx (PLUS, GET_MODE (x),
+			      gen_rtx (MINUS, GET_MODE (x),
+				       XEXP (new0, 0), new1),
+			      XEXP (new0, 1));
+	    else
+	      return gen_rtx (MINUS, GET_MODE (x), new0, new1);
+	  }
+      }
+      return x;
+
     case MULT:
       /* If this is the product of an eliminable register and a 
 	 constant, apply the distribute law and move the constant out
@@ -2920,7 +2942,6 @@ eliminate_regs (x, mem_mode, insn)
 
     case CALL:
     case COMPARE:
-    case MINUS:
     case DIV:      case UDIV:
     case MOD:      case UMOD:
     case AND:      case IOR:      case XOR: