From: Keith Randall <khr@golang.org>
Date: Sat, 12 Sep 2015 21:45:58 +0000 (-0700)
Subject: [dev.ssa] cmd/compile/internal/ssa: don't treat vardef/varkill as reads
X-Git-Tag: go1.7beta1~1623^2^2~167
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=fda72e03751ab876ced9351611e42ad019090ec8;p=gostls13.git

[dev.ssa] cmd/compile/internal/ssa: don't treat vardef/varkill as reads

This makes deadstore elimination work reasonably again.

Change-Id: I3a8caced71f12dfb6c1d0c68b7a7d8d7a736ea23
Reviewed-on: https://go-review.googlesource.com/14536
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
---

diff --git a/src/cmd/compile/internal/ssa/deadstore.go b/src/cmd/compile/internal/ssa/deadstore.go
index 982bd7fa70..89f7504341 100644
--- a/src/cmd/compile/internal/ssa/deadstore.go
+++ b/src/cmd/compile/internal/ssa/deadstore.go
@@ -30,7 +30,7 @@ func dse(f *Func) {
 				for _, a := range v.Args {
 					if a.Block == b && a.Type.IsMemory() {
 						storeUse.add(a.ID)
-						if v.Op != OpStore && v.Op != OpZero {
+						if v.Op != OpStore && v.Op != OpZero && v.Op != OpVarDef && v.Op != OpVarKill {
 							// CALL, DUFFCOPY, etc. are both
 							// reads and writes.
 							loadUse.add(a.ID)