20000317 sourceware import

libgloss/sparc/libsys/libsys-crt0.S

@@ -0,0 +1,127 @@
+! C run time start off
+
+! This file supports:
+!
+! - both 32bit pointer and 64bit pointer environments (at compile time)
+! - an imposed stack bias (of 2047) (at run time)
+! - medium/low and medium/anywhere code models (at run time)
+
+! Initial stack setup:
+!
+!    bottom of stack (higher memory address)
+! 	...
+!	text of environment strings
+!	text of argument strings
+!	envp[envc] = 0 (4/8 bytes)
+!	...
+!	env[0] (4/8 bytes)
+!	argv[argc] = 0 (4/8 bytes)
+!	...
+!	argv[0] (4/8 bytes)
+!	argc (4/8 bytes)
+!	register save area (64 bits by 16 registers = 128 bytes)
+!	top of stack (%sp)
+
+! Stack Bias:
+!
+! It is the responsibility of the o/s to set this up.
+! We handle both a 0 and 2047 value for the stack bias.
+
+! Medium/Anywhere code model support:
+!
+! In this model %g4 points to the start of the data segment.
+! The text segment can go anywhere, but %g4 points to the *data* segment.
+! It is up to the compiler/linker to get this right.
+!
+! Since this model is statically linked the start of the data segment
+! is known at link time.  Eg:
+!
+!	sethi	%hh(data_start), %g1
+!	sethi	%lm(data_start), %g4
+!	or	%g1, %hm(data_start), %g1
+!	or	%g4, %lo(data_start), %g4
+!	sllx	%g1, 32, %g1
+!	or	%g4, %g1, %g4
+!
+! FIXME: For now we just assume 0.
+
+! FIXME: if %g1 contains a non-zero value, atexit() should be invoked
+! with this value.
+
+#include "syscallasm.h"
+
+#ifndef TARGET_PTR_SIZE
+#define TARGET_PTR_SIZE 32
+#endif
+
+	TEXT_SECTION
+	ALIGN (4)
+	GLOBAL (ASM_PRIVATE_SYMBOL (start))
+ASM_PRIVATE_SYMBOL (start):
+	clr	%fp
+
+! We use %g4 even if the code model is Medium/Low (simplifies the code).
+
+	clr	%g4			! Medium/Anywhere base reg
+
+! If there is a stack bias in effect, account for it in %g5.  Then always
+! add %g5 to stack references below.  This way the code can be used with
+! or without an imposed bias.
+
+	andcc	%sp, 1, %g5
+	bnz,a	.LHaveBias
+	mov	2047, %g5
+.LHaveBias:
+	add	%sp, %g5, %sp
+
+#if TARGET_PTR_SIZE == 32
+	! FIXME: We apparently assume here that there is no reserved word.
+	! This is probably correct, but try to verify it.
+	ld	[%sp + 0x80], %o0	! argc
+	add	%sp, 0x84, %o1		! argv
+	add	%o0, 1, %o2
+	sll	%o2, 2, %o2
+#else /* TARGET_PTR_SIZE == 64 */
+	ld	[%sp + 0x8c], %o0	! argc.lo
+	add	%sp, 0x90, %o1		! argv
+	add	%o0, 1, %o2
+	sll	%o2, 3, %o2
+#endif
+	add	%o1, %o2, %o2		! envp
+	sethi	%hi (ASM_SYMBOL (environ)), %o3
+	or	%o3, %lo (ASM_SYMBOL (environ)), %o3
+#if TARGET_PTR_SIZE == 32
+	st	%o2, [%o3 + %g4]
+#else /* TARGET_PTR_SIZE == 64 */
+	stx	%o2, [%o3 + %g4]
+#endif
+
+! Restore any stack bias before we call main() ...
+
+	sub	%sp, %g5, %sp
+
+	GLOBAL (ASM_SYMBOL (main))
+	call	ASM_SYMBOL (main)
+
+! FIXME: Not sure if this is needed anymore.
+#if TARGET_PTR_SIZE == 32
+	sub	%sp, 0x20, %sp		! room to push args
+#else /* TARGET_PTR_SIZE == 64 */
+	sub	%sp, 0x30, %sp		! room to push args
+#endif
+
+	GLOBAL (ASM_SYMBOL (exit))
+	call	ASM_SYMBOL (exit)
+	nop
+
+	GLOBAL (ASM_SYMBOL (_exit))
+	call	ASM_SYMBOL (_exit)
+	nop
+
+	set	SYS_exit, %g1
+	ta	SYSCALL_TRAP		! in case user redefines __exit
+
+! If all the above methods fail to terminate the program, try an illegal insn.
+! If that does not work, the o/s is hosed more than we are.
+
+	WORD (0)