Commit `51fcf949f9`

Shawn Anastasio <shawn@anastas.io>

2020-07-01 23:13:14

Implement std.start for powerpc64le

This is a bit hacky since we end up doing more than just grabbing the stack pointer in the inline assembly block. Ideally _start would be implemented in pure asm for powerpc64le, but this will do for now. Still to be implemented is powerpc, powerpc64, and powerpc64 (ELFv2) support. The latter will just require correctly determing target ABI for powerpc64 and enabling the existing powerpc64le implementation for it.

master

1 parent 8574861

Changed files (1)

lib

std

start.zig

@@ -116,6 +116,21 @@ fn _start() callconv(.Naked) noreturn {
                 : [argc] "=r" (-> [*]usize)
             );
         },
+        .powerpc64le => {
+            // Before returning the stack pointer, we have to set up a backchain
+            // and a few other registers required by the ELFv2 ABI.
+            // TODO: Support powerpc64 (big endian) on ELFv2.
+            starting_stack_ptr = asm (
+                \\ mr 4, 1
+                \\ subi 1, 1, 32
+                \\ li 5, 0
+                \\ std 5, 0(1)
+                \\ mr %[argc], 4
+                : [argc] "=r" (-> [*]usize)
+                :
+                : "r4", "r5"
+            );
+        },
         else => @compileError("unsupported arch"),
     }
     // If LLVM inlines stack variables into _start, they will overwrite

Commit 51fcf949f9

Commit `51fcf949f9`