x86_64: implement calling var args functions

1 files changed, 11 insertions, 4 deletions

diff --git a/src/arch/x86_64/CodeGen.zig b/src/arch/x86_64/CodeGen.zig
index a216ed3c2c..45d8547082 100644
--- a/src/arch/x86_64/CodeGen.zig
+++ b/src/arch/x86_64/CodeGen.zig
@@ -316,7 +316,7 @@ pub fn generate(
     defer function.mir_extra.deinit(bin_file.allocator);
     defer if (builtin.mode == .Debug) function.mir_to_air_map.deinit();
 
-    var call_info = function.resolveCallingConventionValues(fn_type) catch |err| switch (err) {
+    var call_info = function.resolveCallingConventionValues(fn_type, &.{}) catch |err| switch (err) {
         error.CodegenFail => return Result{ .fail = function.err_msg.? },
         error.OutOfRegisters => return Result{
             .fail = try ErrorMsg.create(
@@ -5191,7 +5191,7 @@ fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallModifier
         else => unreachable,
     };
 
-    var info = try self.resolveCallingConventionValues(fn_ty);
+    var info = try self.resolveCallingConventionValues(fn_ty, args[fn_ty.fnParamLen()..]);
     defer info.deinit(self);
 
     try self.spillEflagsIfOccupied();
@@ -8089,11 +8089,18 @@ const CallMCValues = struct {
 };
 
 /// Caller must call `CallMCValues.deinit`.
-fn resolveCallingConventionValues(self: *Self, fn_ty: Type) !CallMCValues {
+fn resolveCallingConventionValues(
+    self: *Self,
+    fn_ty: Type,
+    var_args: []const Air.Inst.Ref,
+) !CallMCValues {
     const cc = fn_ty.fnCallingConvention();
-    const param_types = try self.gpa.alloc(Type, fn_ty.fnParamLen());
+    const param_len = fn_ty.fnParamLen();
+    const param_types = try self.gpa.alloc(Type, param_len + var_args.len);
     defer self.gpa.free(param_types);
     fn_ty.fnParamTypes(param_types);
+    // TODO: promote var arg types
+    for (param_types[param_len..], var_args) |*param_ty, arg| param_ty.* = self.air.typeOf(arg);
     var result: CallMCValues = .{
         .args = try self.gpa.alloc(MCValue, param_types.len),
         // These undefined values must be populated before returning from this function.