Merge pull request #8152 from LemonBoy/fix-riscv-ret

stage1: Follow the C ABI for return types

src/stage1/codegen.cpp

@@ -487,6 +487,53 @@ static LLVMValueRef make_fn_llvm_value(CodeGen *g, ZigFn *fn) {
         addLLVMFnAttr(llvm_fn, "noreturn");
     }
 
+    if (!calling_convention_allows_zig_types(cc)) {
+        // A simplistic and desperate attempt at making the compiler respect the
+        // target ABI for return types.
+        // This is just enough to avoid miscompiling the test suite, it will be
+        // better in stage2.
+        ZigType *int_type = return_type->id == ZigTypeIdInt ? return_type :
+                return_type->id == ZigTypeIdEnum ? return_type->data.enumeration.tag_int_type :
+                nullptr;
+
+        if (int_type != nullptr) {
+            const bool is_signed = int_type->data.integral.is_signed;
+            const uint32_t bit_width = int_type->data.integral.bit_count;
+            bool should_extend = false;
+
+            // Rough equivalent of Clang's isPromotableIntegerType.
+            switch (bit_width) {
+                case 1: // bool
+                case 8: // {un,}signed char
+                case 16: // {un,}signed short
+                    should_extend = true;
+                    break;
+                default:
+                    break;
+            }
+
+            switch (g->zig_target->arch) {
+                case ZigLLVM_sparcv9:
+                case ZigLLVM_riscv64:
+                case ZigLLVM_ppc64:
+                case ZigLLVM_ppc64le:
+                    // Always extend to the register width.
+                    should_extend = bit_width < 64;
+                    break;
+                default:
+                    break;
+            }
+
+            // {zero,sign}-extend the result.
+            if (should_extend) {
+                if (is_signed)
+                    addLLVMAttr(llvm_fn, 0, "signext");
+                else
+                    addLLVMAttr(llvm_fn, 0, "zeroext");
+            }
+        }
+    }
+
     if (fn->body_node != nullptr) {
         maybe_export_dll(g, llvm_fn, linkage);
 

test/stage1/c_abi/cfuncs.c

@@ -24,6 +24,16 @@ void zig_f32(float);
 void zig_f64(double);
 void zig_five_floats(float, float, float, float, float);
 
+bool zig_ret_bool();
+uint8_t zig_ret_u8();
+uint16_t zig_ret_u16();
+uint32_t zig_ret_u32();
+uint64_t zig_ret_u64();
+int8_t zig_ret_i8();
+int16_t zig_ret_i16();
+int32_t zig_ret_i32();
+int64_t zig_ret_i64();
+
 void zig_ptr(void *);
 
 void zig_bool(bool);
@@ -119,6 +129,20 @@ void run_c_tests(void) {
         assert_or_panic(res.d == 23);
         assert_or_panic(res.e == 24);
     }
+
+    {
+        assert_or_panic(zig_ret_bool() == 1);
+
+        assert_or_panic(zig_ret_u8() == 0xff);
+        assert_or_panic(zig_ret_u16() == 0xffff);
+        assert_or_panic(zig_ret_u32() == 0xffffffff);
+        assert_or_panic(zig_ret_u64() == 0xffffffffffffffff);
+
+        assert_or_panic(zig_ret_i8() == -1);
+        assert_or_panic(zig_ret_i16() == -1);
+        assert_or_panic(zig_ret_i32() == -1);
+        assert_or_panic(zig_ret_i64() == -1);
+    }
 }
 
 void c_u8(uint8_t x) {
@@ -236,3 +260,31 @@ void c_big_struct_floats(Vector5 vec) {
     assert_or_panic(vec.w == 69);
     assert_or_panic(vec.q == 55);
 }
+
+bool c_ret_bool() {
+    return 1;
+}
+uint8_t c_ret_u8() {
+    return 0xff;
+}
+uint16_t c_ret_u16() {
+    return 0xffff;
+}
+uint32_t c_ret_u32() {
+    return 0xffffffff;
+}
+uint64_t c_ret_u64() {
+    return 0xffffffffffffffff;
+}
+int8_t c_ret_i8() {
+    return -1;
+}
+int16_t c_ret_i16() {
+    return -1;
+}
+int32_t c_ret_i32() {
+    return -1;
+}
+int64_t c_ret_i64() {
+    return -1;
+}

test/stage1/c_abi/main.zig

@@ -284,3 +284,55 @@ test "C ABI structs of floats as parameter" {
     };
     c_big_struct_floats(v5);
 }
+
+export fn zig_ret_bool() bool {
+    return true;
+}
+export fn zig_ret_u8() u8 {
+    return 0xff;
+}
+export fn zig_ret_u16() u16 {
+    return 0xffff;
+}
+export fn zig_ret_u32() u32 {
+    return 0xffffffff;
+}
+export fn zig_ret_u64() u64 {
+    return 0xffffffffffffffff;
+}
+export fn zig_ret_i8() i8 {
+    return -1;
+}
+export fn zig_ret_i16() i16 {
+    return -1;
+}
+export fn zig_ret_i32() i32 {
+    return -1;
+}
+export fn zig_ret_i64() i64 {
+    return -1;
+}
+
+extern fn c_ret_bool() bool;
+extern fn c_ret_u8() u8;
+extern fn c_ret_u16() u16;
+extern fn c_ret_u32() u32;
+extern fn c_ret_u64() u64;
+extern fn c_ret_i8() i8;
+extern fn c_ret_i16() i16;
+extern fn c_ret_i32() i32;
+extern fn c_ret_i64() i64;
+
+test "C ABI integer return types" {
+    expect(c_ret_bool() == true);
+
+    expect(c_ret_u8() == 0xff);
+    expect(c_ret_u16() == 0xffff);
+    expect(c_ret_u32() == 0xffffffff);
+    expect(c_ret_u64() == 0xffffffffffffffff);
+
+    expect(c_ret_i8() == -1);
+    expect(c_ret_i16() == -1);
+    expect(c_ret_i32() == -1);
+    expect(c_ret_i64() == -1);
+}