Commit 6986d2aca9

Andrew Kelley <andrew@ziglang.org>
2024-05-01 23:39:24
x86_64 sysv C ABI: fix f128 param and return types
Clang 17 passed struct{f128} parameters using rdi and rax, while Clang 18 matches GCC 13.2 behavior, passing them using xmm0. This commit makes Zig's LLVM backend match Clang 18 and GCC 13.2. The commit deletes a hack in x86_64/abi.zig which miscategorized f128 as "memory" which obviously disagreed with the spec.
master
1 parent bc69cb9
Changed files (3)
src
arch
x86_64
abi.zig
CodeGen.zig
codegen
llvm.zig
src/arch/x86_64/abi.zig
@@ -170,10 +170,6 @@ pub fn classifySystemV(ty: Type, zcu: *Zcu, target: std.Target, ctx: Context) [8
                 // "Arguments of types __float128, _Decimal128 and __m128 are
                 // split into two halves.  The least significant ones belong
                 // to class SSE, the most significant one to class SSEUP."
-                if (ctx == .field) {
-                    result[0] = .memory;
-                    return result;
-                }
                 result[0] = .sse;
                 result[1] = .sseup;
                 return result;
src/arch/x86_64/CodeGen.zig
@@ -14318,7 +14318,7 @@ fn moveStrategy(self: *Self, ty: Type, class: Register.Class, aligned: bool) !Mo
             else => {
                 const classes = mem.sliceTo(&abi.classifySystemV(ty, mod, self.target.*, .other), .none);
                 assert(std.mem.indexOfNone(abi.Class, classes, &.{
-                    .integer, .sse, .memory, .float, .float_combine,
+                    .integer, .sse, .sseup, .memory, .float, .float_combine,
                 }) == null);
                 const abi_size = ty.abiSize(mod);
                 if (abi_size < 4 or
src/codegen/llvm.zig
@@ -11167,10 +11167,18 @@ fn lowerSystemVFnRetTy(o: *Object, fn_info: InternPool.Key.FuncType) Allocator.E
                 types_buffer[types_index] = .i64;
                 types_index += 1;
             },
-            .sse, .sseup => {
+            .sse => {
                 types_buffer[types_index] = .double;
                 types_index += 1;
             },
+            .sseup => {
+                if (types_buffer[types_index - 1] == .double) {
+                    types_buffer[types_index - 1] = .fp128;
+                } else {
+                    types_buffer[types_index] = .double;
+                    types_index += 1;
+                }
+            },
             .float => {
                 types_buffer[types_index] = .float;
                 types_index += 1;
@@ -11454,10 +11462,18 @@ const ParamTypeIterator = struct {
                     types_buffer[types_index] = .i64;
                     types_index += 1;
                 },
-                .sse, .sseup => {
+                .sse => {
                     types_buffer[types_index] = .double;
                     types_index += 1;
                 },
+                .sseup => {
+                    if (types_buffer[types_index - 1] == .double) {
+                        types_buffer[types_index - 1] = .fp128;
+                    } else {
+                        types_buffer[types_index] = .double;
+                        types_index += 1;
+                    }
+                },
                 .float => {
                     types_buffer[types_index] = .float;
                     types_index += 1;