From 97d0e8fe6ce41b5961e776ad08abdf0cb6d7af85 Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Fri, 26 Mar 2010 18:01:02 -0700 Subject: [PATCH] gc: allow taking address of out parameters Fixes #186. R=ken2 CC=golang-dev https://golang.org/cl/793041 --- doc/go_spec.html | 2 +- src/cmd/5g/ggen.c | 20 ++++++++++++++++++++ src/cmd/6g/ggen.c | 27 ++++++++++++++++++++++++--- src/cmd/8g/ggen.c | 27 ++++++++++++++++++++++++--- src/cmd/gc/typecheck.c | 6 ++---- src/cmd/gc/walk.c | 26 +++++++++++++++++++++++++- test/escape.go | 32 ++++++++++++++++++++++++++++++++ test/escape1.go | 17 ----------------- 8 files changed, 128 insertions(+), 29 deletions(-) delete mode 100644 test/escape1.go diff --git a/doc/go_spec.html b/doc/go_spec.html index 46dc33e8a0..b35af9b037 100644 --- a/doc/go_spec.html +++ b/doc/go_spec.html @@ -5109,7 +5109,7 @@ The following minimal alignment properties are guaranteed:
  • Method expressions are partially implemented.
  • Gccgo allows only one init() function per source file.
  • Deferred functions cannot access the surrounding function's result parameters.
    • -
  • Function results are not addressable.
    • +
  • Function results are not addressable in gccgo.
  • Recover is not implemented.
  • The implemented version of panic differs from its specification.
    • diff --git a/src/cmd/5g/ggen.c b/src/cmd/5g/ggen.c index e2313d85b6..c60c05863a 100644 --- a/src/cmd/5g/ggen.c +++ b/src/cmd/5g/ggen.c @@ -7,6 +7,8 @@ #include "gg.h" #include "opt.h" +static Prog *pret; + void compile(Node *fn) { @@ -65,6 +67,16 @@ compile(Node *fn) afunclit(&ptxt->from); genlist(curfn->enter); + + pret = nil; + if(hasdefer || curfn->exit) { + Prog *p1; + + p1 = gjmp(nil); + pret = gjmp(nil); + patch(p1, pc); + } + genlist(curfn->nbody); checklabels(); if(nerrors != 0) @@ -73,6 +85,14 @@ compile(Node *fn) if(curfn->type->outtuple != 0) ginscall(throwreturn, 0); + if(pret) + patch(pret, pc); + ginit(); + if(curfn->exit) + genlist(curfn->exit); + gclean(); + if(nerrors != 0) + goto ret; if(hasdefer) ginscall(deferreturn, 0); pc->as = ARET; // overwrite AEND diff --git a/src/cmd/6g/ggen.c b/src/cmd/6g/ggen.c index 99a4aea045..140020fdaf 100644 --- a/src/cmd/6g/ggen.c +++ b/src/cmd/6g/ggen.c @@ -7,6 +7,8 @@ #include "gg.h" #include "opt.h" +static Prog *pret; + void compile(Node *fn) { @@ -66,6 +68,16 @@ compile(Node *fn) ginit(); genlist(curfn->enter); + + pret = nil; + if(hasdefer || curfn->exit) { + Prog *p1; + + p1 = gjmp(nil); + pret = gjmp(nil); + patch(p1, pc); + } + genlist(curfn->nbody); gclean(); checklabels(); @@ -75,6 +87,14 @@ compile(Node *fn) if(curfn->type->outtuple != 0) ginscall(throwreturn, 0); + if(pret) + patch(pret, pc); + ginit(); + if(curfn->exit) + genlist(curfn->exit); + gclean(); + if(nerrors != 0) + goto ret; if(hasdefer) ginscall(deferreturn, 0); pc->as = ARET; // overwrite AEND @@ -325,9 +345,10 @@ void cgen_ret(Node *n) { genlist(n->list); // copy out args - if(hasdefer) - ginscall(deferreturn, 0); - gins(ARET, N, N); + if(hasdefer || curfn->exit) + gjmp(pret); + else + gins(ARET, N, N); } /* diff --git a/src/cmd/8g/ggen.c b/src/cmd/8g/ggen.c index 23177c2408..468f67ae98 100644 --- a/src/cmd/8g/ggen.c +++ b/src/cmd/8g/ggen.c @@ -7,6 +7,8 @@ #include "gg.h" #include "opt.h" +static Prog *pret; + void compile(Node *fn) { @@ -66,6 +68,16 @@ compile(Node *fn) ginit(); genlist(curfn->enter); + + pret = nil; + if(hasdefer || curfn->exit) { + Prog *p1; + + p1 = gjmp(nil); + pret = gjmp(nil); + patch(p1, pc); + } + genlist(curfn->nbody); gclean(); checklabels(); @@ -75,6 +87,14 @@ compile(Node *fn) if(curfn->type->outtuple != 0) ginscall(throwreturn, 0); + if(pret) + patch(pret, pc); + ginit(); + if(curfn->exit) + genlist(curfn->exit); + gclean(); + if(nerrors != 0) + goto ret; if(hasdefer) ginscall(deferreturn, 0); pc->as = ARET; // overwrite AEND @@ -362,9 +382,10 @@ void cgen_ret(Node *n) { genlist(n->list); // copy out args - if(hasdefer) - ginscall(deferreturn, 0); - gins(ARET, N, N); + if(pret) + gjmp(pret); + else + gins(ARET, N, N); } /* diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c index d10bf8f74b..c219ad8c53 100644 --- a/src/cmd/gc/typecheck.c +++ b/src/cmd/gc/typecheck.c @@ -1988,17 +1988,15 @@ addrescapes(Node *n) if(n->noescape) break; switch(n->class) { - case PPARAMOUT: - yyerror("cannot take address of out parameter %s", n->sym->name); - break; case PAUTO: case PPARAM: + case PPARAMOUT: // if func param, need separate temporary // to hold heap pointer. // the function type has already been checked // (we're in the function body) // so the param already has a valid xoffset. - if(n->class == PPARAM) { + if(n->class == PPARAM || n->class == PPARAMOUT) { // expression to refer to stack copy n->stackparam = nod(OPARAM, n, N); n->stackparam->type = n->type; diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c index 9c904f14c6..fa6157bb02 100644 --- a/src/cmd/gc/walk.c +++ b/src/cmd/gc/walk.c @@ -2288,7 +2288,29 @@ paramstoheap(Type **argin) if(v->alloc == nil) v->alloc = callnew(v->type); nn = list(nn, nod(OAS, v->heapaddr, v->alloc)); - nn = list(nn, nod(OAS, v, v->stackparam)); + if((v->class & ~PHEAP) != PPARAMOUT) + nn = list(nn, nod(OAS, v, v->stackparam)); + } + return nn; +} + +/* + * walk through argout parameters copying back to stack + */ +NodeList* +returnsfromheap(Type **argin) +{ + Type *t; + Iter savet; + Node *v; + NodeList *nn; + + nn = nil; + for(t = structfirst(&savet, argin); t != T; t = structnext(&savet)) { + v = t->nname; + if(v == N || v->class != (PHEAP|PPARAMOUT)) + continue; + nn = list(nn, nod(OAS, v->stackparam, v)); } return nn; } @@ -2305,7 +2327,9 @@ heapmoves(void) nn = paramstoheap(getthis(curfn->type)); nn = concat(nn, paramstoheap(getinarg(curfn->type))); + nn = concat(nn, paramstoheap(getoutarg(curfn->type))); curfn->enter = concat(curfn->enter, nn); + curfn->exit = returnsfromheap(getoutarg(curfn->type)); } static Node* diff --git a/test/escape.go b/test/escape.go index 2c5881d49c..19c08a5276 100644 --- a/test/escape.go +++ b/test/escape.go @@ -141,6 +141,24 @@ func for_escapes2(x int, y int) (*int, *int) { return p[0], p[1] } +func out_escapes(i int) (x int, p *int) { + x = i + p = &x; // ERROR "address of out parameter" + return; +} + +func out_escapes_2(i int) (x int, p *int) { + x = i + return x, &x; // ERROR "address of out parameter" +} + +func defer1(i int) (x int) { + c := make(chan int) + go func() { x = i; c <- 1 }() + <-c + return +} + func main() { p, q := i_escapes(1), i_escapes(2); chk(p, q, 1, "i_escapes"); @@ -169,6 +187,20 @@ func main() { p, q = for_escapes2(103, 104); chkalias(p, q, 103, "for_escapes2"); + _, p = out_escapes(15) + _, q = out_escapes(16); + chk(p, q, 15, "out_escapes"); + + _, p = out_escapes_2(17) + _, q = out_escapes_2(18); + chk(p, q, 17, "out_escapes_2"); + + x := defer1(20) + if x != 20 { + println("defer failed", x) + bad = true + } + if bad { panic("BUG: no escape"); } diff --git a/test/escape1.go b/test/escape1.go deleted file mode 100644 index 646e4b3519..0000000000 --- a/test/escape1.go +++ /dev/null @@ -1,17 +0,0 @@ -// errchk $G $D/$F.go - -// Copyright 2009 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -package main - -func out_escapes() (x int, p *int) { - p = &x; // ERROR "address of out parameter" - return; -} - -func out_escapes_2() (x int, p *int) { - return 2, &x; // ERROR "address of out parameter" -} -