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8005522: use fast-string instructions on x86 for zeroing

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Use 'rep stosb' instead of 'rep stosq' when fast-string operations are available.

Reviewed-by: twisti, roland
This commit is contained in:
Vladimir Kozlov 2013-01-03 15:09:55 -08:00
parent 73d6d417be
commit cfcd28fd9d
10 changed files with 95 additions and 22 deletions
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14
hotspot/src/cpu/x86/vm/assembler_x86.cpp
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@ -2544,12 +2544,18 @@ void Assembler::rep_mov() {
emit_int8((unsigned char)0xA5);
}
// sets rcx bytes with rax, value at [edi]
void Assembler::rep_stosb() {
emit_int8((unsigned char)0xF3); // REP
LP64_ONLY(prefix(REX_W));
emit_int8((unsigned char)0xAA); // STOSB
}
// sets rcx pointer sized words with rax, value at [edi]
// generic
void Assembler::rep_set() { // rep_set
emit_int8((unsigned char)0xF3);
// STOSQ
LP64_ONLY(prefix(REX_W));
void Assembler::rep_stos() {
emit_int8((unsigned char)0xF3); // REP
LP64_ONLY(prefix(REX_W)); // LP64:STOSQ, LP32:STOSD
emit_int8((unsigned char)0xAB);
}