From 36b414f6397cadffab1a945eed645a3213f39d8a Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Wed, 6 Mar 2013 15:03:04 -0500
Subject: [PATCH] runtime: change amd64 startup convention

Now the default startup is that the program begins at _rt0_amd64_$GOOS,
which sets DI = argc, SI = argv and jumps to _rt0_amd64.

This makes the _rt0_amd64 entry match the expected semantics for
the standard C "main" function, which we can now provide for use when
linking against a standard C library.

R=golang-dev, devon.odell, minux.ma
CC=golang-dev
https://golang.org/cl/7525043
---
 src/pkg/runtime/asm_amd64.s         |  4 ++--
 src/pkg/runtime/rt0_darwin_amd64.s  | 11 +++++++----
 src/pkg/runtime/rt0_freebsd_amd64.s | 12 ++++++++----
 src/pkg/runtime/rt0_linux_amd64.s   | 11 +++++++----
 src/pkg/runtime/rt0_netbsd_amd64.s  | 13 +++++++++----
 src/pkg/runtime/rt0_openbsd_amd64.s | 11 ++++++++---
 src/pkg/runtime/rt0_plan9_amd64.s   |  5 +++--
 src/pkg/runtime/rt0_windows_amd64.s |  9 +++++++--
 8 files changed, 51 insertions(+), 25 deletions(-)

diff --git a/src/pkg/runtime/asm_amd64.s b/src/pkg/runtime/asm_amd64.s
index 696befd6e4d..a671f39925c 100644
--- a/src/pkg/runtime/asm_amd64.s
+++ b/src/pkg/runtime/asm_amd64.s
@@ -6,8 +6,8 @@
 
 TEXT _rt0_amd64(SB),7,$-8
 	// copy arguments forward on an even stack
-	MOVQ	0(DI), AX		// argc
-	LEAQ	8(DI), BX		// argv
+	MOVQ	DI, AX		// argc
+	MOVQ	SI, BX		// argv
 	SUBQ	$(4*8+7), SP		// 2args 2auto
 	ANDQ	$~15, SP
 	MOVQ	AX, 16(SP)
diff --git a/src/pkg/runtime/rt0_darwin_amd64.s b/src/pkg/runtime/rt0_darwin_amd64.s
index 4cfab587644..45e69a01596 100644
--- a/src/pkg/runtime/rt0_darwin_amd64.s
+++ b/src/pkg/runtime/rt0_darwin_amd64.s
@@ -2,9 +2,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Darwin and Linux use the same linkage to main
-
 TEXT _rt0_amd64_darwin(SB),7,$-8
-	MOVQ	$_rt0_amd64(SB), AX
-	MOVQ	SP, DI
+	LEAQ	8(SP), SI // argv
+	MOVQ	0(SP), DI // argc
+	MOVQ	$main(SB), AX
+	JMP	AX
+
+TEXT main(SB),7,$-8
+	MOVQ	$_rt0_amd64(SB), AX
 	JMP	AX
diff --git a/src/pkg/runtime/rt0_freebsd_amd64.s b/src/pkg/runtime/rt0_freebsd_amd64.s
index 5d2eeeefff4..e6c6fb9cac7 100644
--- a/src/pkg/runtime/rt0_freebsd_amd64.s
+++ b/src/pkg/runtime/rt0_freebsd_amd64.s
@@ -2,8 +2,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Darwin and Linux use the same linkage to main
-
 TEXT _rt0_amd64_freebsd(SB),7,$-8
-	MOVQ	$_rt0_amd64(SB), DX
-	JMP	DX
+	LEAQ	8(DI), SI // argv
+	MOVQ	0(DI), DI // argc
+	MOVQ	$main(SB), AX
+	JMP	AX
+
+TEXT main(SB),7,$-8
+	MOVQ	$_rt0_amd64(SB), AX
+	JMP	AX
diff --git a/src/pkg/runtime/rt0_linux_amd64.s b/src/pkg/runtime/rt0_linux_amd64.s
index dac9ae181b0..dfc9c0421bd 100644
--- a/src/pkg/runtime/rt0_linux_amd64.s
+++ b/src/pkg/runtime/rt0_linux_amd64.s
@@ -2,9 +2,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Darwin and Linux use the same linkage to main
-
 TEXT _rt0_amd64_linux(SB),7,$-8
-	MOVQ	$_rt0_amd64(SB), AX
-	MOVQ	SP, DI
+	LEAQ	8(SP), SI // argv
+	MOVQ	0(SP), DI // argc
+	MOVQ	$main(SB), AX
+	JMP	AX
+
+TEXT main(SB),7,$-8
+	MOVQ	$_rt0_amd64(SB), AX
 	JMP	AX
diff --git a/src/pkg/runtime/rt0_netbsd_amd64.s b/src/pkg/runtime/rt0_netbsd_amd64.s
index 85482b98db2..245a4c0f9b4 100644
--- a/src/pkg/runtime/rt0_netbsd_amd64.s
+++ b/src/pkg/runtime/rt0_netbsd_amd64.s
@@ -2,7 +2,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-TEXT _rt0_amd64_netbsd(SB),7,$-8
-	MOVQ	$_rt0_amd64(SB), DX
-	MOVQ	SP, DI
-	JMP	DX
+TEXT _rt0_amd64_openbsd(SB),7,$-8
+	LEAQ	8(SP), SI // argv
+	MOVQ	0(SP), DI // argc
+	MOVQ	$main(SB), AX
+	JMP	AX
+
+TEXT main(SB),7,$-8
+	MOVQ	$_rt0_amd64(SB), AX
+	JMP	AX
diff --git a/src/pkg/runtime/rt0_openbsd_amd64.s b/src/pkg/runtime/rt0_openbsd_amd64.s
index e7fce596968..245a4c0f9b4 100644
--- a/src/pkg/runtime/rt0_openbsd_amd64.s
+++ b/src/pkg/runtime/rt0_openbsd_amd64.s
@@ -3,6 +3,11 @@
 // license that can be found in the LICENSE file.
 
 TEXT _rt0_amd64_openbsd(SB),7,$-8
-	MOVQ	$_rt0_amd64(SB), DX
-	MOVQ	SP, DI
-	JMP	DX
+	LEAQ	8(SP), SI // argv
+	MOVQ	0(SP), DI // argc
+	MOVQ	$main(SB), AX
+	JMP	AX
+
+TEXT main(SB),7,$-8
+	MOVQ	$_rt0_amd64(SB), AX
+	JMP	AX
diff --git a/src/pkg/runtime/rt0_plan9_amd64.s b/src/pkg/runtime/rt0_plan9_amd64.s
index 2b1fa2ae1dd..16e5e82b755 100644
--- a/src/pkg/runtime/rt0_plan9_amd64.s
+++ b/src/pkg/runtime/rt0_plan9_amd64.s
@@ -2,9 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-TEXT _rt0_amd64_plan9(SB),7, $0
+TEXT _rt0_amd64_plan9(SB),7,$-8
+	LEAQ	8(SP), SI // argv
+	MOVQ	0(SP), DI // argc
 	MOVQ	$_rt0_amd64(SB), AX
-	MOVQ	SP, DI
 	JMP	AX
 
 DATA runtime·isplan9(SB)/4, $1
diff --git a/src/pkg/runtime/rt0_windows_amd64.s b/src/pkg/runtime/rt0_windows_amd64.s
index dc1408adc35..4fc61dc687b 100644
--- a/src/pkg/runtime/rt0_windows_amd64.s
+++ b/src/pkg/runtime/rt0_windows_amd64.s
@@ -4,9 +4,14 @@
 
 #include "zasm_GOOS_GOARCH.h"
 
-TEXT	_rt0_amd64_windows(SB),7,$-8
+TEXT _rt0_amd64_darwin(SB),7,$-8
+	LEAQ	8(SP), SI // argv
+	MOVQ	0(SP), DI // argc
+	MOVQ	$main(SB), AX
+	JMP	AX
+
+TEXT main(SB),7,$-8
 	MOVQ	$_rt0_amd64(SB), AX
-	MOVQ	SP, DI
 	JMP	AX
 
 DATA  runtime·iswindows(SB)/4, $1