From fff732ea2c4d3cb449c4383a6957ff80ca75c70a Mon Sep 17 00:00:00 2001
From: Jamie Gennis <jgennis@google.com>
Date: Wed, 8 Feb 2012 10:25:13 -0500
Subject: [PATCH] 6g,8g: make constant propagation inlining-friendly.

This changes makes constant propagation compare 'from' values using node
pointers rather than symbol names when checking to see whether a set
operation is redundant. When a function is inlined multiple times in a
calling function its arguments will share symbol names even though the values
are different. Prior to this fix the bug409 test would hit a case with 6g
where an LEAQ instruction was incorrectly eliminated from the second inlined
function call. 8g appears to have had the same bug, but the test did not fail
there.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5646044
---
 src/cmd/6g/peep.c         |  2 +-
 src/cmd/8g/peep.c         |  2 +-
 test/fixedbugs/bug409.go  | 20 ++++++++++++++++++++
 test/fixedbugs/bug409.out |  1 +
 4 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 test/fixedbugs/bug409.go
 create mode 100644 test/fixedbugs/bug409.out

diff --git a/src/cmd/6g/peep.c b/src/cmd/6g/peep.c
index 63ef3f78f0c..3710033b20d 100644
--- a/src/cmd/6g/peep.c
+++ b/src/cmd/6g/peep.c
@@ -987,7 +987,7 @@ loop:
 	case 3:	// set
 		if(p->as == p0->as)
 		if(p->from.type == p0->from.type)
-		if(p->from.sym == p0->from.sym)
+		if(p->from.node == p0->from.node)
 		if(p->from.offset == p0->from.offset)
 		if(p->from.scale == p0->from.scale)
 		if(p->from.dval == p0->from.dval)
diff --git a/src/cmd/8g/peep.c b/src/cmd/8g/peep.c
index e0e44a5ef48..b8a2825e5a8 100644
--- a/src/cmd/8g/peep.c
+++ b/src/cmd/8g/peep.c
@@ -878,7 +878,7 @@ loop:
 	case 3:	// set
 		if(p->as == p0->as)
 		if(p->from.type == p0->from.type)
-		if(p->from.sym == p0->from.sym)
+		if(p->from.node == p0->from.node)
 		if(p->from.offset == p0->from.offset)
 		if(p->from.scale == p0->from.scale)
 		if(p->from.dval == p0->from.dval)
diff --git a/test/fixedbugs/bug409.go b/test/fixedbugs/bug409.go
new file mode 100644
index 00000000000..884d3337087
--- /dev/null
+++ b/test/fixedbugs/bug409.go
@@ -0,0 +1,20 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out 2>&1 | cmp - $D/$F.out
+
+// Copyright 2012 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.
+
+// Multiple inlined calls to a function that causes
+// redundant address loads.
+
+package main
+
+func F(v [2]float64) [2]float64 {
+	return [2]float64{v[0], v[1]}
+}
+
+func main() {
+	a := F([2]float64{1, 2})
+	b := F([2]float64{3, 4})
+	println(a[0], a[1], b[0], b[1])
+}
diff --git a/test/fixedbugs/bug409.out b/test/fixedbugs/bug409.out
new file mode 100644
index 00000000000..3cb40ed59a9
--- /dev/null
+++ b/test/fixedbugs/bug409.out
@@ -0,0 +1 @@
++1.000000e+000 +2.000000e+000 +3.000000e+000 +4.000000e+000