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comparison src/cpu/x86/vm/assembler_x86.cpp @ 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 d02120b7a34f
children e2e6bf86682c
comparison
equal deleted inserted replaced
7473:d092d1b31229 7474:00af3a3a8df4
2542 // MOVSQ 2542 // MOVSQ
2543 LP64_ONLY(prefix(REX_W)); 2543 LP64_ONLY(prefix(REX_W));
2544 emit_int8((unsigned char)0xA5); 2544 emit_int8((unsigned char)0xA5);
2545 } 2545 }
2546 2546
2547 // sets rcx bytes with rax, value at [edi]
2548 void Assembler::rep_stosb() {
2549 emit_int8((unsigned char)0xF3); // REP
2550 LP64_ONLY(prefix(REX_W));
2551 emit_int8((unsigned char)0xAA); // STOSB
2552 }
2553
2547 // sets rcx pointer sized words with rax, value at [edi] 2554 // sets rcx pointer sized words with rax, value at [edi]
2548 // generic 2555 // generic
2549 void Assembler::rep_set() { // rep_set 2556 void Assembler::rep_stos() {
2550 emit_int8((unsigned char)0xF3); 2557 emit_int8((unsigned char)0xF3); // REP
2551 // STOSQ 2558 LP64_ONLY(prefix(REX_W)); // LP64:STOSQ, LP32:STOSD
2552 LP64_ONLY(prefix(REX_W));
2553 emit_int8((unsigned char)0xAB); 2559 emit_int8((unsigned char)0xAB);
2554 } 2560 }
2555 2561
2556 // scans rcx pointer sized words at [edi] for occurance of rax, 2562 // scans rcx pointer sized words at [edi] for occurance of rax,
2557 // generic 2563 // generic