Simplify _start routines

sys$__environment was unused since 94ee9832f5861c4d09afa12338720eb3a479c342.
Delete it and count, which is no longer needed.

Simplify _start routines since they no longer need to allocate space for the
environment slice and populate it.

1 files changed, 14 insertions, 36 deletions

diff --git a/rt/start-openbsd.s b/rt/start-openbsd.s
index 663d865..ad62bf4 100644
--- a/rt/start-openbsd.s
+++ b/rt/start-openbsd.s
@@ -8,15 +8,7 @@
 	.p2align 2
 
 .data
-
-/* sys._environment : byte[:][:] */
-.globl sys$__environment
-sys$__environment:
-    .envbase:
-    .quad 0 /* env size */
-    .envlen:
-    .quad 0 /* env ptr */
-
+/* sys.__cenvp : byte## */
 .globl sys$__cenvp
 sys$__cenvp:
     .quad 0
@@ -26,45 +18,31 @@ sys$__cenvp:
  * The entry point for the whole program.
  * This is called by the OS. In order, it:
  *  - Sets up all argc entries as slices
- *  - Sets up all envp entries as slices
  *  - Converts argc/argv to a slice
- *  - Stashes envp in sys._environment
  *  - Stashes a raw envp copy in __cenvp (for syscalls to use)
  *  - Calls main()
  */
 .globl _start
 _start:
-	/* turn args into a slice */
 	movq	%rsp,%rbp
 
-	/* stack allocate sizeof(byte[:])*(argc + len(envp)) */
-	movq	(%rbp),%rax
-	leaq	16(%rbp,%rax,8), %rbx	/* argp = argv + 8*argc + 8 */
-	call    count
-	addq	%r9,%rax
-	imulq	$16,%rax
-	subq	%rax,%rsp
-	movq	%rsp, %rdx	/* saved args[:] */
+	/* load argc, argv, envp from stack */
+	movq	(%rbp),%rax		/* argc */
+	leaq	8(%rbp),%rbx		/* argv */
+	leaq	16(%rbp,%rax,8),%rcx	/* envp = argv + 8*argc + 8 */
 
-	/* convert envp to byte[:][:] for sys._environment */
-	movq	(%rbp),%rax
-	leaq	16(%rbp,%rax,8), %rbx	/* envp = argv + 8*argc + 8 */
 	/* store envp for some syscalls to use without converting */
-	movq    %rbx,sys$__cenvp(%rip)
-	movq	%r9,%rax
-	movq	%rsp, %rcx
-	movq	%r9,.envlen(%rip)
-	movq	%rdx,.envbase(%rip)
-	call	cvt
-	movq	%rcx,%rdx
-	
+	movq    %rcx,sys$__cenvp(%rip)
+
+	/* stack allocate sizeof(byte[:])*argc */
+	imulq	$16,%rax,%rdx
+	subq	%rdx,%rsp
+	movq	%rsp,%rcx		/* args[:] */
+
 	/* convert argc, argv to byte[:][:] for args. */
-	movq	(%rbp), %rax	/* argc */
-	leaq	8(%rbp), %rbx	/* argv */
-	movq	(%rbp), %rsi	/* saved argc */
+	pushq	%rax
+	pushq	%rcx
 	call	cvt
-	pushq	%rsi
-	pushq	%rdx
 
 	xorq %rbp,%rbp
 	/* call pre-main initializers */