Add anddi_1 -> andsi_1_zext splitter (PR target/53639)

Message ID
State New
Headers show

Commit Message

Jakub Jelinek June 12, 2012, 9:22 p.m.

The combiner combines
(set (reg:SI x) (and:SI (reg:SI y) (const_int 1234)))
(set (reg:DI z) (zero_extend:DI (reg:SI x)))
(set (reg:DI z) (and:DI (subreg:DI (reg:SI (y) 0) (const_int 1234))))
which unfortunately isn't the best form on x86_64 from RA POV, because
if y needs to be moved around, with the paradoxical subreg it is copied
around as DImode which is one byte longer than SImode copy.  We only
need the low 32-bits from that though.

The following patch fixes it, by splitting what combiner creates before RA
into andsi_1_zext pattern.  My initial version of the patch did it for all
DImode operands[1], but that unfortunately regressed pr49095.c where
mem &= const with flag setting is no longer being peepholed.  So, this patch
limits it to whatever combiner creates.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2012-06-12  Jakub Jelinek  <>

	PR target/53639
	* config/i386/ (*anddi_1 into *andsi_1_zext splitter): New.



Richard Henderson June 12, 2012, 9:39 p.m. | #1
On 2012-06-12 14:22, Jakub Jelinek wrote:
> 	PR target/53639
> 	* config/i386/ (*anddi_1 into *andsi_1_zext splitter): New.




--- gcc/config/i386/	2012-06-12 09:46:26.449838954 +0200
+++ gcc/config/i386/	2012-06-12 12:22:58.972769925 +0200
@@ -7933,6 +7933,18 @@  (define_insn "*andqi_1_slp"
   [(set_attr "type" "alu1")
    (set_attr "mode" "QI")])
+;; Turn *anddi_1 into *andsi_1_zext if possible.
+  [(set (match_operand:DI 0 "register_operand")
+	(and:DI (subreg:DI (match_operand:SI 1 "register_operand") 0)
+		(match_operand:DI 2 "x86_64_zext_immediate_operand")))
+   (clobber (reg:CC FLAGS_REG))]
+  [(parallel [(set (match_dup 0)
+		   (zero_extend:DI (and:SI (match_dup 1) (match_dup 2))))
+	      (clobber (reg:CC FLAGS_REG))])]
+  "operands[2] = gen_lowpart (SImode, operands[2]);")
   [(set (match_operand:SWI248 0 "register_operand")
 	(and:SWI248 (match_operand:SWI248 1 "nonimmediate_operand")