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runtime: speed up eqstring
eqstring does not need to check the length of the strings. 6g benchmark old ns/op new ns/op delta BenchmarkCompareStringEqual 7.03 6.14 -12.66% BenchmarkCompareStringIdentical 3.36 3.04 -9.52% 5g benchmark old ns/op new ns/op delta BenchmarkCompareStringEqual 238 232 -2.52% BenchmarkCompareStringIdentical 90.8 80.7 -11.12% The equivalent PPC changes are in a separate commit because I don't have the hardware to test them. Change-Id: I292874324b9bbd9d24f57a390cfff8b550cdd53c Reviewed-on: https://go-review.googlesource.com/3955 Reviewed-by: Keith Randall <khr@golang.org>
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@ -1273,6 +1273,7 @@ walkexpr(Node **np, NodeList **init)
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conv(n->right, types[TSTRING]));
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// quick check of len before full compare for == or !=
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// eqstring assumes that the lengths are equal
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if(n->etype == OEQ) {
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// len(left) == len(right) && eqstring(left, right)
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r = nod(OANDAND, nod(OEQ, nod(OLEN, n->left, N), nod(OLEN, n->right, N)), r);
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@ -1298,26 +1298,22 @@ eq:
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RET
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// eqstring tests whether two strings are equal.
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// The compiler guarantees that strings passed
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// to eqstring have equal length.
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// See runtime_test.go:eqstring_generic for
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// equivalent Go code.
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TEXT runtime·eqstring(SB),NOSPLIT,$0-17
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MOVL s1len+4(FP), AX
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MOVL s2len+12(FP), BX
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CMPL AX, BX
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JNE different
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MOVL s1str+0(FP), SI
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MOVL s2str+8(FP), DI
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CMPL SI, DI
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JEQ same
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MOVL s1len+4(FP), BX
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CALL runtime·memeqbody(SB)
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MOVB AX, v+16(FP)
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RET
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same:
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MOVB $1, v+16(FP)
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RET
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different:
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MOVB $0, v+16(FP)
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RET
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TEXT bytes·Equal(SB),NOSPLIT,$0-25
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MOVL a_len+4(FP), BX
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@ -1262,26 +1262,22 @@ eq:
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RET
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// eqstring tests whether two strings are equal.
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// The compiler guarantees that strings passed
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// to eqstring have equal length.
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// See runtime_test.go:eqstring_generic for
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// equivalent Go code.
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TEXT runtime·eqstring(SB),NOSPLIT,$0-33
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MOVQ s1len+8(FP), AX
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MOVQ s2len+24(FP), BX
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CMPQ AX, BX
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JNE noteq
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MOVQ s1str+0(FP), SI
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MOVQ s2str+16(FP), DI
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CMPQ SI, DI
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JEQ eq
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MOVQ s1len+8(FP), BX
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CALL runtime·memeqbody(SB)
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MOVB AX, v+32(FP)
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RET
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eq:
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MOVB $1, v+32(FP)
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RET
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noteq:
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MOVB $0, v+32(FP)
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RET
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// a in SI
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// b in DI
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@ -704,26 +704,22 @@ eq:
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RET
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// eqstring tests whether two strings are equal.
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// The compiler guarantees that strings passed
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// to eqstring have equal length.
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// See runtime_test.go:eqstring_generic for
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// equivalent Go code.
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TEXT runtime·eqstring(SB),NOSPLIT,$0-17
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MOVL s1len+4(FP), AX
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MOVL s2len+12(FP), BX
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CMPL AX, BX
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JNE different
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MOVL s1str+0(FP), SI
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MOVL s2str+8(FP), DI
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CMPL SI, DI
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JEQ same
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MOVL s1len+4(FP), BX
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CALL runtime·memeqbody(SB)
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MOVB AX, v+16(FP)
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RET
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same:
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MOVB $1, v+16(FP)
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RET
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different:
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MOVB $0, v+16(FP)
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RET
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// a in SI
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// b in DI
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@ -806,21 +806,18 @@ eq:
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RET
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// eqstring tests whether two strings are equal.
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// The compiler guarantees that strings passed
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// to eqstring have equal length.
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// See runtime_test.go:eqstring_generic for
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// equivalent Go code.
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TEXT runtime·eqstring(SB),NOSPLIT,$-4-17
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MOVW s1len+4(FP), R0
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MOVW s2len+12(FP), R1
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MOVW $0, R7
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CMP R0, R1
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MOVB.NE R7, v+16(FP)
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RET.NE
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MOVW s1str+0(FP), R2
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MOVW s2str+8(FP), R3
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MOVW $1, R8
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MOVB R8, v+16(FP)
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CMP R2, R3
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RET.EQ
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MOVW s1len+4(FP), R0
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ADD R2, R0, R6
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loop:
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CMP R2, R6
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@ -829,7 +826,8 @@ loop:
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MOVBU.P 1(R3), R5
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CMP R4, R5
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BEQ loop
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MOVB R7, v+16(FP)
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MOVW $0, R8
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MOVB R8, v+16(FP)
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RET
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// void setg_gcc(G*); set g called from gcc.
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