From: Matthew Dempsky <mdempsky@google.com>
Date: Thu, 12 Mar 2020 19:14:02 +0000 (-0700)
Subject: cmd/compile: skip generating args_stackmap for "pulled" funcs
X-Git-Tag: go1.15beta1~793
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=bb929b7452b5b8a6a584a94a110c98b0c6543a6e;p=gostls13.git

cmd/compile: skip generating args_stackmap for "pulled" funcs

In golang.org/cl/171464, we cleaned up generation of .stkobj linker
symbols, but we couldn't figure out why a similar cleanup to
.args_stackmap linker symbols caused problems.

The issue is that we only need/want to generate .args_stackmap for
functions that are implemented in assembly in the same package. When
"pulling" a function from another package via //go:linkname, we can
safely skip emitting .args_stackmap, because compiling that package
will have generated it, if necessary.

Fixes #31615.

Change-Id: If8680aa7dd5b4e8f268b6b032d746f1b8536c867
Reviewed-on: https://go-review.googlesource.com/c/go/+/223238
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
---

diff --git a/src/cmd/compile/internal/gc/pgen.go b/src/cmd/compile/internal/gc/pgen.go
index e8141b5237..6ccd0b8d94 100644
--- a/src/cmd/compile/internal/gc/pgen.go
+++ b/src/cmd/compile/internal/gc/pgen.go
@@ -12,7 +12,6 @@ import (
 	"cmd/internal/objabi"
 	"cmd/internal/src"
 	"cmd/internal/sys"
-	"fmt"
 	"internal/race"
 	"math/rand"
 	"sort"
@@ -28,11 +27,10 @@ var (
 )
 
 func emitptrargsmap(fn *Node) {
-	if fn.funcname() == "_" {
+	if fn.funcname() == "_" || fn.Func.Nname.Sym.Linkname != "" {
 		return
 	}
-	sym := lookup(fmt.Sprintf("%s.args_stackmap", fn.funcname()))
-	lsym := sym.Linksym()
+	lsym := Ctxt.Lookup(fn.Func.lsym.Name + ".args_stackmap")
 
 	nptr := int(fn.Type.ArgWidth() / int64(Widthptr))
 	bv := bvalloc(int32(nptr) * 2)