From: Keith Randall <khr@golang.org>
Date: Sat, 11 Jul 2015 21:41:22 +0000 (-0700)
Subject: [dev.ssa] cmd/compile/internal/ssa: Phi inputs from dead blocks are not live
X-Git-Tag: go1.7beta1~1623^2^2~400
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=050ce4390aa16b03e7272e22e79de165589319b5;p=gostls13.git

[dev.ssa] cmd/compile/internal/ssa: Phi inputs from dead blocks are not live

Fixes #11676

Change-Id: I941f951633c89bb1454ce6d1d1b4124d46a7d9dd
Reviewed-on: https://go-review.googlesource.com/12091
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
---

diff --git a/src/cmd/compile/internal/ssa/deadcode.go b/src/cmd/compile/internal/ssa/deadcode.go
index 2be7b8ebaf..1b1ae27e58 100644
--- a/src/cmd/compile/internal/ssa/deadcode.go
+++ b/src/cmd/compile/internal/ssa/deadcode.go
@@ -44,7 +44,10 @@ func deadcode(f *Func) {
 		// pop a reachable value
 		v := q[len(q)-1]
 		q = q[:len(q)-1]
-		for _, x := range v.Args {
+		for i, x := range v.Args {
+			if v.Op == OpPhi && !reachable[v.Block.Preds[i].ID] {
+				continue
+			}
 			if !live[x.ID] {
 				live[x.ID] = true
 				q = append(q, x) // push