compiler: remove @setAlignStack

This commit finishes implementing #21209 by removing the
`@setAlignStack` builtin in favour of `CallingConvention` payloads. The
x86_64 backend is updated to use the stack alignment given in the
calling convention (the LLVM backend was already updated in a previous
commit).

Resolves: #21209

1 files changed, 16 insertions, 0 deletions

diff --git a/src/target.zig b/src/target.zig
index 7d30781f43..7a5c3387b6 100644
--- a/src/target.zig
+++ b/src/target.zig
@@ -607,3 +607,19 @@ pub inline fn backendSupportsFeature(backend: std.builtin.CompilerBackend, compt
         },
     };
 }
+
+pub fn stackAlignment(target: std.Target, cc: std.builtin.CallingConvention) u64 {
+    switch (cc) {
+        inline else => |payload| switch (@TypeOf(payload)) {
+            std.builtin.CallingConvention.CommonOptions,
+            std.builtin.CallingConvention.X86RegparmOptions,
+            std.builtin.CallingConvention.ArmInterruptOptions,
+            std.builtin.CallingConvention.MipsInterruptOptions,
+            std.builtin.CallingConvention.RiscvInterruptOptions,
+            => if (payload.incoming_stack_alignment) |a| return a,
+            void => {},
+            else => comptime unreachable,
+        },
+    }
+    return target.stackAlignment();
+}