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diff src/cpu/x86/vm/x86_32.ad @ 7474:00af3a3a8df4

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8005522: use fast-string instructions on x86 for zeroing Summary: use 'rep stosb' instead of 'rep stosq' when fast-string operations are available. Reviewed-by: twisti, roland
author kvn
date Thu, 03 Jan 2013 15:09:55 -0800
parents d804e148cff8
children b30b3c2a0cf2
line wrap: on
line diff
--- a/src/cpu/x86/vm/x86_32.ad	Sun Dec 23 17:08:22 2012 +0100
+++ b/src/cpu/x86/vm/x86_32.ad	Thu Jan 03 15:09:55 2013 -0800
@@ -11572,15 +11572,28 @@
 // =======================================================================
 // fast clearing of an array
 instruct rep_stos(eCXRegI cnt, eDIRegP base, eAXRegI zero, Universe dummy, eFlagsReg cr) %{
+  predicate(!UseFastStosb);
   match(Set dummy (ClearArray cnt base));
   effect(USE_KILL cnt, USE_KILL base, KILL zero, KILL cr);
-  format %{ "SHL    ECX,1\t# Convert doublewords to words\n\t"
-            "XOR    EAX,EAX\n\t"
+  format %{ "XOR    EAX,EAX\t# ClearArray:\n\t"
+            "SHL    ECX,1\t# Convert doublewords to words\n\t"
             "REP STOS\t# store EAX into [EDI++] while ECX--" %}
-  opcode(0,0x4);
-  ins_encode( Opcode(0xD1), RegOpc(ECX),
-              OpcRegReg(0x33,EAX,EAX),
-              Opcode(0xF3), Opcode(0xAB) );
+  ins_encode %{ 
+    __ clear_mem($base$$Register, $cnt$$Register, $zero$$Register);
+  %}
+  ins_pipe( pipe_slow );
+%}
+
+instruct rep_fast_stosb(eCXRegI cnt, eDIRegP base, eAXRegI zero, Universe dummy, eFlagsReg cr) %{
+  predicate(UseFastStosb);
+  match(Set dummy (ClearArray cnt base));
+  effect(USE_KILL cnt, USE_KILL base, KILL zero, KILL cr);
+  format %{ "XOR    EAX,EAX\t# ClearArray:\n\t"
+            "SHL    ECX,3\t# Convert doublewords to bytes\n\t"
+            "REP STOSB\t# store EAX into [EDI++] while ECX--" %}
+  ins_encode %{ 
+    __ clear_mem($base$$Register, $cnt$$Register, $zero$$Register);
+  %}
   ins_pipe( pipe_slow );
 %}