From: Josh Bleecher Snyder <josharian@gmail.com>
Date: Tue, 28 Apr 2020 17:20:55 +0000 (-0700)
Subject: cmd/compile: simplify readonly sym checks in writebarrier pass
X-Git-Tag: go1.15beta1~325
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=71e0cd815def852085a1592fbd64a149b437be55;p=gostls13.git

cmd/compile: simplify readonly sym checks in writebarrier pass

CL 220499 started marking readonly syms as SRODATA earlier,
so we can use that in the writebarrier pass now.

Passes toolstash-check.

Change-Id: Ic4d49714b8bffbe03c8e9a75ca96df4475bae732
Reviewed-on: https://go-review.googlesource.com/c/go/+/230559
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
---

diff --git a/src/cmd/compile/internal/ssa/writebarrier.go b/src/cmd/compile/internal/ssa/writebarrier.go
index cebfbb8c9d..c7fb059475 100644
--- a/src/cmd/compile/internal/ssa/writebarrier.go
+++ b/src/cmd/compile/internal/ssa/writebarrier.go
@@ -7,9 +7,9 @@ package ssa
 import (
 	"cmd/compile/internal/types"
 	"cmd/internal/obj"
+	"cmd/internal/objabi"
 	"cmd/internal/src"
 	"fmt"
-	"strings"
 )
 
 // A ZeroRegion records parts of an object which are known to be zero.
@@ -565,8 +565,7 @@ func IsReadOnlyGlobalAddr(v *Value) bool {
 		// Nil pointers are read only. See issue 33438.
 		return true
 	}
-	// See TODO in OpAddr case in IsSanitizerSafeAddr below.
-	if v.Op == OpAddr && strings.HasPrefix(v.Aux.(*obj.LSym).Name, `""..stmp_`) {
+	if v.Op == OpAddr && v.Aux.(*obj.LSym).Type == objabi.SRODATA {
 		return true
 	}
 	return false
@@ -614,15 +613,7 @@ func IsSanitizerSafeAddr(v *Value) bool {
 		// read-only once initialized.
 		return true
 	case OpAddr:
-		sym := v.Aux.(*obj.LSym)
-		// TODO(mdempsky): Find a cleaner way to
-		// detect this. It would be nice if we could
-		// test sym.Type==objabi.SRODATA, but we don't
-		// initialize sym.Type until after function
-		// compilation.
-		if strings.HasPrefix(sym.Name, `""..stmp_`) {
-			return true
-		}
+		return v.Aux.(*obj.LSym).Type == objabi.SRODATA
 	}
 	return false
 }