From f570d9d7657edcccb52b2ec9a55cb90a28602d57 Mon Sep 17 00:00:00 2001
From: Anthony Martin <ality@pbrane.org>
Date: Mon, 16 May 2011 22:14:56 -0400
Subject: [PATCH] 8g: fix conversion from float to uint64
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The code for converting negative floats was
incorrectly loading an FP control word from
the stack without ever having stored it there.

Thanks to Lars Pensjö for reporting this bug.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4515091
---
 src/cmd/8g/gsubr.c       |  4 ++--
 test/fixedbugs/bug341.go | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)
 create mode 100644 test/fixedbugs/bug341.go

diff --git a/src/cmd/8g/gsubr.c b/src/cmd/8g/gsubr.c
index e3f239d6051..5ad35fdce72 100644
--- a/src/cmd/8g/gsubr.c
+++ b/src/cmd/8g/gsubr.c
@@ -1429,11 +1429,11 @@ gmove(Node *f, Node *t)
 		split64(t, &tlo, &thi);
 		gins(AXORL, ncon(0x80000000), &thi);	// + 2^63
 		patch(p3, pc);
-		patch(p1, pc);
 		splitclean();
-
 		// restore rounding mode
 		gins(AFLDCW, &t1, N);
+
+		patch(p1, pc);
 		return;
 
 	/*
diff --git a/test/fixedbugs/bug341.go b/test/fixedbugs/bug341.go
new file mode 100644
index 00000000000..8ee52e1ef05
--- /dev/null
+++ b/test/fixedbugs/bug341.go
@@ -0,0 +1,22 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out || echo BUG: bug341
+
+// Copyright 2011 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.
+
+// Used to panic because 8g was generating incorrect
+// code for converting a negative float to a uint64.
+
+package main
+
+func main() {
+	var x float32 = -2.5
+
+	_ = uint64(x)
+	_ = float32(0)
+}
+/*
+panic: runtime error: floating point error
+
+[signal 0x8 code=0x6 addr=0x8048c64 pc=0x8048c64]
+*/