[patch] Rewrite libc/sys/h8300hms/_exit.c in assembly.

[Kazu Hirata]

Hi,

Attached is a patch to rewrite _exit.c in assembly.

The first two asm statements in each function in _exit.c write their
results into r1 and r2, but nothing guarantees that their values are
kept until the "sleep" instruction, which "uses" the values.

The patch fixes the problem by rewriting the whole thing in assembly.

This bug is triggered by gcc from tree-ssa branch, where "rc << 8" is
performed in SImode, requiring a scratch register, which happens to be
one of the registers that needs to be preserved until "sleep".

Tested by building newlib with gcc.  OK to apply?

Kazu Hirata

2004-03-10  Kazu Hirata  <kazu@cs.umass.edu>

	* libc/sys/h8300hms/Makefile.am (lib_a_SOURCES): Replace
	_exit.c with _exit.S.
	* libc/sys/h8300hms/Makefile.in: Regenerate.
	* libc/sys/h8300hms/_exit.c: Remove.
	* libc/sys/h8300hms/_exit.S: New.

Index: Makefile.am
===================================================================
RCS file: /cvs/src/src/newlib/libc/sys/h8300hms/Makefile.am,v
retrieving revision 1.3
diff -u -r1.3 Makefile.am
--- Makefile.am	25 Feb 2003 20:36:29 -0000	1.3
+++ Makefile.am	10 Mar 2004 18:35:09 -0000
@@ -6,7 +6,7 @@
 
 noinst_LIBRARIES = lib.a
 
-lib_a_SOURCES = syscalls.c _exit.c sbrk.c misc.c crt1.c \
+lib_a_SOURCES = syscalls.c _exit.S sbrk.c misc.c crt1.c \
 	close.S fstat.S lseek.S open.S read.S stat.S write.S
 
 all: crt0.o
Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/newlib/libc/sys/h8300hms/Makefile.in,v
retrieving revision 1.8
diff -u -r1.8 Makefile.in
--- Makefile.in	23 Jan 2004 21:37:38 -0000	1.8
+++ Makefile.in	10 Mar 2004 18:35:09 -0000
@@ -89,7 +89,8 @@
 
 noinst_LIBRARIES = lib.a
 
-lib_a_SOURCES = syscalls.c _exit.c sbrk.c misc.c crt1.c 	close.S fstat.S lseek.S open.S read.S stat.S write.S
+lib_a_SOURCES = syscalls.c _exit.S sbrk.c misc.c crt1.c \
+	close.S fstat.S lseek.S open.S read.S stat.S write.S
 
 
 ACLOCAL_AMFLAGS = -I ../../..
Index: _exit.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/sys/h8300hms/_exit.c,v
retrieving revision 1.2
diff -u -r1.2 _exit.c
--- _exit.c	31 Jan 2003 20:44:26 -0000	1.2
+++ _exit.c	10 Mar 2004 18:37:17 -0000
@@ -1,36 +0,1 @@
-/* FIXME: which one? */
-
-#include <_ansi.h>
-
-/* `sleep' is passed an argument in r0 that indicates the reason
-   the program is exiting.  The format of r0 is defined in devo/include/wait.h.
-*/
-
-void
-_DEFUN (_exit,(rc),
-     int rc)
-{
-  short rc2;
-
-  rc2 = 0xdead;
-  asm("mov.w %0,r1" : : "r" (rc2) : "r1");
-  rc2 = 0xbeef;
-  asm("mov.w %0,r2" : : "r" (rc2) : "r2");
-  rc2 = rc << 8;
-  asm("mov.w %0,r0\n\tsleep" : : "r" (rc2) : "r0");
-}
-
-void
-_DEFUN (__exit,(rc),
-     int rc)
-{
-  short rc2;
-
-  rc2 = 0xdead;
-  asm("mov.w %0,r1" : : "r" (rc2) : "r1");
-  rc2 = 0xbeef;
-  asm("mov.w %0,r2" : : "r" (rc2) : "r2");
-  rc2 = rc << 8;
-  asm("mov.w %0,r0\n\tsleep" : : "r" (rc2) : "r0");
-}
--- /dev/null	2003-09-15 09:40:47.000000000 -0400
+++ _exit.S	2004-03-10 13:34:08.827057456 -0500
@@ -0,0 +1,28 @@
+#include "setarch.h"
+
+/* `sleep' is passed an argument in r0 that indicates the reason
+   the program is exiting.  The format of r0 is defined in devo/include/wait.h.
+*/
+
+/* FIXME: which one? */
+/* extern void _exit (int rc); */
+/* extern void __exit (int rc); */
+
+	.section .text
+	.align 2
+	.global __exit
+__exit:
+	mov.w	#0xdead,r1
+	mov.w	#0xbeef,r2
+	mov.b	r0l,r0h
+	sub.b	r0l,r0l
+	sleep
+	.align 2
+	.global ___exit
+___exit:
+	mov.w	#0xdead,r1
+	mov.w	#0xbeef,r2
+	mov.b	r0l,r0h
+	sub.b	r0l,r0l
+	sleep
+	.end