zig

commit 792526c0bd45754bced18298573ad2a145a7141e (tree)
parent cdbf66e36ec110993347e5158005ec1cc0adaf13
Author: Koakuma <koachan@protonmail.com>
Date:   Sat, 24 Oct 2020 19:54:58 +0700

Fix sparc64 argument loading

Diffstat:
M
lib/std/start.zig
 | 
10
++++++++--

1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/lib/std/start.zig b/lib/std/start.zig
@@ -148,8 +148,14 @@ fn _start() callconv(.Naked) noreturn {
             );
         },
         .sparcv9 => {
-            starting_stack_ptr = asm (""
-                : [argc] "={o6}" (-> [*]usize)
+            // On sparc64, the stack pointer register points to a place
+            // 2047 bytes below the actual stack. Also, argc and friends are
+            // placed starting at [stack-start + 128], so we need to account for that too.
+            // Ref: System V Application Binary Interface: SPARC Version 9 Processor Supplement
+            // Version 1.35, figure 3-16.
+            // TODO: find a better way to do this.
+            starting_stack_ptr = asm ("add %%o6, 2175, %[argc]"
+                : [argc] "=r" (-> [*]usize)
             );
         },
         else => @compileError("unsupported arch"),