From 4dec8ef35a0071064b3fd68203ae5ce66c6f9b6b Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Tue, 4 Aug 2009 19:16:57 -0700
Subject: [PATCH] get function calls out of the way before allocating registers
 in shift and div.

fix behavior when res == a reserved register.

R=ken
OCL=32765
CL=32767
---
 src/cmd/6g/ggen.c         | 58 +++++++++++++++++++++++++++++++--------
 src/pkg/time/time_test.go |  8 +++---
 test/fixedbugs/bug180.go  | 17 ++++++++++++
 3 files changed, 68 insertions(+), 15 deletions(-)
 create mode 100644 test/fixedbugs/bug180.go

diff --git a/src/cmd/6g/ggen.c b/src/cmd/6g/ggen.c
index f51839f49b2..63dbd68354b 100644
--- a/src/cmd/6g/ggen.c
+++ b/src/cmd/6g/ggen.c
@@ -534,28 +534,37 @@ dodiv(int op, Node *nl, Node *nr, Node *res, Node *ax, Node *dx)
 void
 cgen_div(int op, Node *nl, Node *nr, Node *res)
 {
-	Node ax, dx, oldax, olddx;
+	Node ax, dx, oldax, olddx, n1, n2;
 	int rax, rdx;
 
-	if(nl->ullman >= UINF || nr->ullman >= UINF)
-		fatal("cgen_div UINF");
+	if(nl->ullman >= UINF) {
+		tempname(&n1, nl->type);
+		cgen(nl, &n1);
+		nl = &n1;
+	}
+	if(nr->ullman >= UINF) {
+		tempname(&n2, nr->type);
+		cgen(nr, &n2);
+		nr = &n2;
+	}
 
 	rax = reg[D_AX];
 	rdx = reg[D_DX];
-	
+
 	nodreg(&ax, types[TINT64], D_AX);
 	nodreg(&dx, types[TINT64], D_DX);
 	regalloc(&ax, nl->type, &ax);
 	regalloc(&dx, nl->type, &dx);
 
 	// save current ax and dx if they are live
+	// and not the destination
 	memset(&oldax, 0, sizeof oldax);
 	memset(&olddx, 0, sizeof olddx);
-	if(rax > 0) {
+	if(rax > 0 && !samereg(&ax, res)) {
 		regalloc(&oldax, nl->type, N);
 		gmove(&ax, &oldax);
 	}
-	if(rdx > 0) {
+	if(rdx > 0 && !samereg(&dx, res)) {
 		regalloc(&olddx, nl->type, N);
 		gmove(&dx, &olddx);
 	}
@@ -565,11 +574,11 @@ cgen_div(int op, Node *nl, Node *nr, Node *res)
 	regfree(&ax);
 	regfree(&dx);
 	
-	if(rax > 0) {
+	if(oldax.op != 0) {
 		gmove(&oldax, &ax);
 		regfree(&oldax);
 	}
-	if(rdx > 0) {
+	if(olddx.op != 0) {
 		gmove(&olddx, &dx);
 		regfree(&olddx);
 	}
@@ -584,8 +593,8 @@ cgen_div(int op, Node *nl, Node *nr, Node *res)
 void
 cgen_shift(int op, Node *nl, Node *nr, Node *res)
 {
-	Node n1, n2, n3;
-	int a;
+	Node n1, n2, n3, n4, n5, cx, oldcx;
+	int a, rcx;
 	Prog *p1;
 	uvlong sc;
 
@@ -607,11 +616,33 @@ cgen_shift(int op, Node *nl, Node *nr, Node *res)
 		goto ret;
 	}
 
+	if(nl->ullman >= UINF) {
+		tempname(&n4, nl->type);
+		cgen(nl, &n4);
+		nl = &n4;
+	}
+	if(nr->ullman >= UINF) {
+		tempname(&n5, nr->type);
+		cgen(nr, &n5);
+		nr = &n5;
+	}
+
+	rcx = reg[D_CX];
 	nodreg(&n1, types[TUINT32], D_CX);
 	regalloc(&n1, nr->type, &n1);		// to hold the shift type in CX
 	regalloc(&n3, types[TUINT64], &n1);	// to clear high bits of CX
 
-	regalloc(&n2, nl->type, res);
+	nodreg(&cx, types[TUINT64], D_CX);
+	memset(&oldcx, 0, sizeof oldcx);
+	if(rcx > 0 && !samereg(&cx, res)) {
+		regalloc(&oldcx, types[TUINT64], N);
+		gmove(&cx, &oldcx);
+	}
+
+	if(samereg(&cx, res))
+		regalloc(&n2, nl->type, N);
+	else
+		regalloc(&n2, nl->type, res);
 	if(nl->ullman >= nr->ullman) {
 		cgen(nl, &n2);
 		cgen(nr, &n1);
@@ -637,6 +668,11 @@ cgen_shift(int op, Node *nl, Node *nr, Node *res)
 	patch(p1, pc);
 	gins(a, &n1, &n2);
 
+	if(oldcx.op != 0) {
+		gmove(&oldcx, &cx);
+		regfree(&oldcx);
+	}
+
 	gmove(&n2, res);
 
 	regfree(&n1);
diff --git a/src/pkg/time/time_test.go b/src/pkg/time/time_test.go
index 41e6736e836..2457d8561ad 100644
--- a/src/pkg/time/time_test.go
+++ b/src/pkg/time/time_test.go
@@ -60,8 +60,8 @@ func TestSecondsToUTC(t *testing.T) {
 		}
 		if !same(tm, golden) {
 			t.Errorf("SecondsToUTC(%d):", sec);
-			t.Errorf("  want=%v", *golden);
-			t.Errorf("  have=%v", *tm);
+			t.Errorf("  want=%+v", *golden);
+			t.Errorf("  have=%+v", *tm);
 		}
 	}
 }
@@ -77,8 +77,8 @@ func TestSecondsToLocalTime(t *testing.T) {
 		}
 		if !same(tm, golden) {
 			t.Errorf("SecondsToLocalTime(%d):", sec);
-			t.Errorf("  want=%v", *golden);
-			t.Errorf("  have=%v", *tm);
+			t.Errorf("  want=%+v", *golden);
+			t.Errorf("  have=%+v", *tm);
 		}
 	}
 }
diff --git a/test/fixedbugs/bug180.go b/test/fixedbugs/bug180.go
new file mode 100644
index 00000000000..e2934486058
--- /dev/null
+++ b/test/fixedbugs/bug180.go
@@ -0,0 +1,17 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2009 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.
+
+package main
+
+func shift(x int) int {
+	return 1<<(1<<(1<<(uint(x))));
+}
+
+func main() {
+	if n := shift(2); n != 1<<(1<<(1<<2)) {
+		panicln("bad shift", n);
+	}
+}