[PATCH, i386]: Convert some more simple LEAs to ADD.

[Uros Bizjak]

Hello!

Sometimes, gcc generates:

leaq    (%rbx,%rax), %rax

that is in fact equivalent (modulo flags reg clobber) to:

addq    %rbx, %rax

Attached patch adds additional peephole2 patterns that convert LEA to
ADD when second operand of PLUS RTX matches output operand.

2012-07-06  Uros Bizjak  <ubizjak@gmail.com>

	* config/i386/i386.md (simple lea to add peephole): Also transform
	RTXes where second PLUS operand matches output.

Tested on x86_64-pc-linux-gnu {,-m32}, committed to mainline SVN.

Uros.
-------------- next part --------------
Index: config/i386/i386.md
===================================================================
--- config/i386/i386.md	(revision 189310)
+++ config/i386/i386.md	(working copy)
@@ -17301,6 +17301,14 @@
 	      (clobber (reg:CC FLAGS_REG))])])
 
 (define_peephole2
+  [(set (match_operand:SWI48 0 "register_operand")
+  	(plus:SWI48 (match_operand:SWI48 1 "<nonmemory_operand>")
+		    (match_dup 0)))]
+  "peep2_regno_dead_p (0, FLAGS_REG)"
+  [(parallel [(set (match_dup 0) (plus:SWI48 (match_dup 0) (match_dup 1)))
+	      (clobber (reg:CC FLAGS_REG))])])
+
+(define_peephole2
   [(set (match_operand:SI 0 "register_operand")
   	(subreg:SI (plus:DI (match_operand:DI 1 "register_operand")
 			    (match_operand:DI 2 "nonmemory_operand")) 0))]
@@ -17312,6 +17320,17 @@
   "operands[2] = gen_lowpart (SImode, operands[2]);")
 
 (define_peephole2
+  [(set (match_operand:SI 0 "register_operand")
+  	(subreg:SI (plus:DI (match_operand:DI 1 "nonmemory_operand")
+			    (match_operand:DI 2 "register_operand")) 0))]
+  "TARGET_64BIT
+   && peep2_regno_dead_p (0, FLAGS_REG)
+   && REGNO (operands[0]) == REGNO (operands[2])"
+  [(parallel [(set (match_dup 0) (plus:SI (match_dup 0) (match_dup 1)))
+	      (clobber (reg:CC FLAGS_REG))])]
+  "operands[1] = gen_lowpart (SImode, operands[1]);")
+
+(define_peephole2
   [(set (match_operand:SWI48 0 "register_operand")
   	(mult:SWI48 (match_dup 0)
 		    (match_operand:SWI48 1 "const_int_operand")))]