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https://github.com/golang/go
synced 2024-11-21 21:34:40 -07:00
gc: optimize interface ==, !=
If the values being compared have different concrete types, then they're clearly unequal without needing to invoke the actual interface compare routine. This speeds tests for specific values, like if err == io.EOF, by about 3x. benchmark old ns/op new ns/op delta BenchmarkIfaceCmp100 843 287 -65.95% BenchmarkIfaceCmpNil100 184 182 -1.09% Fixes #2591. R=ken2 CC=golang-dev https://golang.org/cl/5651073
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@ -64,6 +64,9 @@ cgen(Node *n, Node *res)
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if(isslice(n->left->type))
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n->addable = n->left->addable;
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break;
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case OITAB:
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n->addable = n->left->addable;
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break;
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}
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// if both are addressable, move
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@ -280,6 +283,20 @@ cgen(Node *n, Node *res)
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regfree(&n1);
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break;
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case OITAB:
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// itable of interface value
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igen(nl, &n1, res);
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n1.op = OREGISTER; // was OINDREG
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regalloc(&n2, n->type, &n1);
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n1.op = OINDREG;
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n1.type = n->type;
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n1.xoffset = 0;
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gmove(&n1, &n2);
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gmove(&n2, res);
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regfree(&n1);
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regfree(&n2);
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break;
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case OLEN:
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if(istype(nl->type, TMAP) || istype(nl->type, TCHAN)) {
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// map has len in the first 32-bit word.
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@ -346,6 +346,8 @@ anyregalloc(void)
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return 0;
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}
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uintptr regpc[REGALLOC_RMAX+1];
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/*
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* allocate register of type t, leave in n.
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* if o != N, o is desired fixed register.
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@ -389,9 +391,12 @@ regalloc(Node *n, Type *t, Node *o)
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goto out;
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}
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for(i=REGALLOC_R0; i<=REGALLOC_RMAX; i++)
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if(reg[i] == 0)
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if(reg[i] == 0) {
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regpc[i] = (uintptr)getcallerpc(&n);
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goto out;
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}
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for(i=REGALLOC_R0; i<=REGALLOC_RMAX; i++)
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print("%d %p\n", i, regpc[i]);
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yyerror("out of fixed registers");
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goto err;
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@ -451,6 +456,8 @@ regfree(Node *n)
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if(reg[i] <= 0)
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fatal("regfree: reg not allocated");
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reg[i]--;
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if(reg[i] == 0)
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regpc[i] = 0;
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}
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/*
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@ -1347,6 +1354,16 @@ naddr(Node *n, Addr *a, int canemitcode)
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}
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break;
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case OITAB:
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// itable of interface value
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naddr(n->left, a, canemitcode);
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a->etype = TINT32;
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if(a->type == D_CONST && a->offset == 0)
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break; // len(nil)
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if(a->offset >= unmappedzero && a->offset-Array_nel < unmappedzero)
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checkoffset(a, canemitcode);
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break;
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case OLEN:
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// len of string or slice
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naddr(n->left, a, canemitcode);
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@ -125,6 +125,9 @@ cgen(Node *n, Node *res)
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if(isslice(n->left->type))
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n->addable = n->left->addable;
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break;
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case OITAB:
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n->addable = n->left->addable;
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break;
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}
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if(complexop(n, res)) {
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@ -259,6 +262,14 @@ cgen(Node *n, Node *res)
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gmove(&n1, res);
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regfree(&n1);
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break;
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case OITAB:
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// interface table is first word of interface value
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igen(nl, &n1, res);
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n1.type = n->type;
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gmove(&n1, res);
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regfree(&n1);
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break;
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case OLEN:
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if(istype(nl->type, TMAP) || istype(nl->type, TCHAN)) {
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@ -563,6 +563,7 @@ int
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ismem(Node *n)
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{
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switch(n->op) {
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case OITAB:
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case OLEN:
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case OCAP:
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case OINDREG:
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@ -1219,6 +1220,17 @@ naddr(Node *n, Addr *a, int canemitcode)
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break;
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}
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fatal("naddr: OADDR\n");
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case OITAB:
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// itable of interface value
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naddr(n->left, a, canemitcode);
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if(a->type == D_CONST && a->offset == 0)
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break; // itab(nil)
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a->etype = tptr;
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a->width = widthptr;
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if(a->offset >= unmappedzero && a->offset-Array_nel < unmappedzero)
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checkoffset(a, canemitcode);
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break;
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case OLEN:
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// len of string or slice
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@ -98,6 +98,9 @@ cgen(Node *n, Node *res)
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if(isslice(n->left->type))
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n->addable = n->left->addable;
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break;
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case OITAB:
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n->addable = n->left->addable;
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break;
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}
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// if both are addressable, move
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@ -252,6 +255,13 @@ cgen(Node *n, Node *res)
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regfree(&n1);
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break;
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case OITAB:
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igen(nl, &n1, res);
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n1.type = ptrto(types[TUINTPTR]);
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gmove(&n1, res);
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regfree(&n1);
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break;
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case OLEN:
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if(istype(nl->type, TMAP) || istype(nl->type, TCHAN)) {
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// map has len in the first 32-bit word.
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@ -1041,6 +1041,7 @@ int
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ismem(Node *n)
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{
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switch(n->op) {
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case OITAB:
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case OLEN:
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case OCAP:
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case OINDREG:
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@ -1926,6 +1927,17 @@ naddr(Node *n, Addr *a, int canemitcode)
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break;
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}
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fatal("naddr: OADDR\n");
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case OITAB:
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// itable of interface value
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naddr(n->left, a, canemitcode);
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if(a->type == D_CONST && a->offset == 0)
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break; // len(nil)
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a->etype = tptr;
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a->width = widthptr;
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if(a->offset >= unmappedzero && a->offset-Array_nel < unmappedzero)
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checkoffset(a, canemitcode);
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break;
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case OLEN:
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// len of string or slice
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@ -484,6 +484,7 @@ enum
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ODDD,
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ODDDARG,
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OINLCALL, // intermediary representation of an inlined call
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OITAB, // itable word of interface value
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// for back ends
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OCMP, ODEC, OEXTEND, OINC, OREGISTER, OINDREG,
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@ -1304,6 +1304,16 @@ reswitch:
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if(n->type == T)
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goto error;
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goto ret;
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case OITAB:
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ok |= Erv;
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typecheck(&n->left, Erv);
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if((t = n->left->type) == T)
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goto error;
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if(t->etype != TINTER)
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fatal("OITAB of %T", t);
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n->type = ptrto(types[TUINTPTR]);
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goto ret;
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/*
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* statements
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@ -432,6 +432,10 @@ walkexpr(Node **np, NodeList **init)
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walkexpr(&n->left, init);
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goto ret;
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case OITAB:
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walkexpr(&n->left, init);
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goto ret;
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case OLEN:
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case OCAP:
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walkexpr(&n->left, init);
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@ -1176,10 +1180,21 @@ walkexpr(Node **np, NodeList **init)
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argtype(fn, n->right->type);
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argtype(fn, n->left->type);
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r = mkcall1(fn, n->type, init, n->left, n->right);
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if(n->etype == ONE) {
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if(n->etype == ONE)
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r = nod(ONOT, r, N);
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typecheck(&r, Erv);
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}
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// check itable/type before full compare.
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if(n->etype == OEQ)
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r = nod(OANDAND, nod(OEQ, nod(OITAB, n->left, N), nod(OITAB, n->right, N)), r);
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else
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r = nod(OOROR, nod(ONE, nod(OITAB, n->left, N), nod(OITAB, n->right, N)), r);
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typecheck(&r, Erv);
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walkexpr(&r, nil);
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n = r;
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goto ret;
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n = r;
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goto ret;
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40
src/pkg/runtime/runtime_test.go
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40
src/pkg/runtime/runtime_test.go
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@ -0,0 +1,40 @@
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// Copyright 2012 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime_test
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import (
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"io"
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"testing"
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)
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var errf error
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func errfn() error {
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return errf
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}
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func errfn1() error {
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return io.EOF
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}
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func BenchmarkIfaceCmp100(b *testing.B) {
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for i := 0; i < b.N; i++ {
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for j := 0; j < 100; j++ {
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if errfn() == io.EOF {
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b.Fatal("bad comparison")
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}
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}
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}
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}
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func BenchmarkIfaceCmpNil100(b *testing.B) {
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for i := 0; i < b.N; i++ {
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for j := 0; j < 100; j++ {
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if errfn1() == nil {
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b.Fatal("bad comparison")
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}
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}
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}
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}
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