GCC could return __int128 values in SSE (%xmm0) on Windows x64 instead
of following the MS x64 ABI. Root cause: return classification allowed
128-bit integer-like scalars to be treated as direct register returns.
This patch updates the Windows x64 return-classification and codegen to
treat int128 as an indirect return (caller-provided slot passed as first
argument, pointer returned in RAX).
gcc/ChangeLog:
PR target/78799
* config/i386/i386.cc (function_value_ms_64): Do not treat
integral 16-byte values as SSE returns.
(ix86_return_in_memory): Likewise avoid treating integral
16-byte values as XMM returns.
gcc/testsuite/ChangeLog:
PR target/78799
* gcc.target/i386/pr78799.c: New test.
Signed-off-by: Oleg Tolmatcev <[email protected]>
---
Changes in v2:
- Remove the leftover SCALAR_INT_MODE_P (mode) check from ix86_return_in_memory.
I don't have commit right for the git repository.
gcc/config/i386/i386.cc | 6 ++----
gcc/testsuite/gcc.target/i386/pr78799.c | 15 +++++++++++++++
2 files changed, 17 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/i386/pr78799.c
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 33b4c13d0f..fd4db40f4f 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -4360,10 +4360,9 @@ function_value_ms_64 (machine_mode orig_mode,
machine_mode mode,
break;
if (valtype != NULL_TREE
&& !VECTOR_INTEGER_TYPE_P (valtype)
- && !INTEGRAL_TYPE_P (valtype)
&& !VECTOR_FLOAT_TYPE_P (valtype))
break;
- if ((SCALAR_INT_MODE_P (mode) || VECTOR_MODE_P (mode))
+ if (VECTOR_MODE_P (mode)
&& !COMPLEX_MODE_P (mode))
regno = FIRST_SSE_REG;
break;
@@ -4470,9 +4469,8 @@ ix86_return_in_memory (const_tree type, const_tree fntype
ATTRIBUTE_UNUSED)
/* __m128 is returned in xmm0. 256/512-bit vector values are
returned in ymm0/zmm0 when AVX/AVX512 is enabled. */
if ((!type || VECTOR_INTEGER_TYPE_P (type)
- || INTEGRAL_TYPE_P (type)
|| VECTOR_FLOAT_TYPE_P (type))
- && (SCALAR_INT_MODE_P (mode) || VECTOR_MODE_P (mode))
+ && VECTOR_MODE_P (mode)
&& !COMPLEX_MODE_P (mode)
&& ((GET_MODE_SIZE (mode) == 16 || size == 16)
|| (TARGET_AVX && (GET_MODE_SIZE (mode) == 32 || size == 32))
diff --git a/gcc/testsuite/gcc.target/i386/pr78799.c
b/gcc/testsuite/gcc.target/i386/pr78799.c
new file mode 100644
index 0000000000..fcd6fe3c9d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr78799.c
@@ -0,0 +1,15 @@
+/* { dg-do compile { target { x86_64-*-mingw* } } } */
+/* { dg-options "-O2" } */
+
+/* PR78799: verify Win64 __int128 return uses an indirect sret-style path:
+ RCX points to the return slot, RDX points to the argument object. */
+__attribute__((ms_abi, noinline, noclone))
+__int128
+ret_i128 (__int128 a)
+{
+ return a;
+}
+
+/* { dg-final { scan-assembler "movdqa\t\\(%rdx\\), %xmm0" } } */
+/* { dg-final { scan-assembler "movq\t%rcx, %rax" } } */
+/* { dg-final { scan-assembler "movaps\t%xmm0, \\(%rcx\\)" } } */
--
2.54.0.windows.1
