Segher Boessenkool <seg...@kernel.crashing.org> writes:
> On Sat, Feb 08, 2020 at 10:17:42AM -0600, Segher Boessenkool wrote:
>> And we do not know which of the register will be used for the return, in
>> untyped_call (only untyped-return knows). But we can add clobbers of all
>> registers that *might* be used for the return, we do know that here, see
>> operands[2] of untyped_call.
>
> Clobbers in parallel to the call, I mean, not as separate insns later.
>
Thanks Segher, as discussed, we may refine the patch by adding a
'barrier' to avoid instructions mis-scheduled. This improvement patch
maybe fine for practice.
Below is the updated patch: bootstrap and regtest pass on powerpc64le.
Is this ok to submit to trunk?
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index f3c8eb0..2fbe68f 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -10867,6 +10867,10 @@
emit_call_insn (gen_call (operands[0], const0_rtx, const0_rtx));
+ for (int i = 0; i < XVECLEN (operands[2], 0); i++)
+ emit_clobber (SET_SRC (XVECEXP (operands[2], 0, i)));
+ emit_insn (gen_blockage ());
+
for (i = 0; i < XVECLEN (operands[2], 0); i++)
{
rtx set = XVECEXP (operands[2], 0, i);
diff --git a/gcc/testsuite/gcc.dg/torture/stackalign/builtin-return-2.c
b/gcc/testsuite/gcc.dg/torture/stackalign/builtin-return-2.c
new file mode 100644
index 0000000..7719109
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/stackalign/builtin-return-2.c
@@ -0,0 +1,40 @@
+/* PR target/93047 */
+/* Originator: Andrew Church <gcczi...@achurch.org> */
+/* { dg-do run } */
+/* { dg-additional-options "-O3 -frename-registers" } */
+/* { dg-require-effective-target untyped_assembly } */
+
+#ifdef __MMIX__
+/* No parameters on stack for bar. */
+#define STACK_ARGUMENTS_SIZE 0
+#else
+#define STACK_ARGUMENTS_SIZE 64
+#endif
+
+extern void abort(void);
+
+int foo(int n)
+{
+ return n+1;
+}
+
+int bar(int n)
+{
+ __builtin_return(__builtin_apply((void (*)(void))foo, __builtin_apply_args(),
+ STACK_ARGUMENTS_SIZE));
+}
+
+int main(void)
+{
+ /* Allocate 64 bytes on the stack to make sure that __builtin_apply
+ can read at least 64 bytes above the return address. */
+ char dummy[64];
+
+ __asm__ ("" : : "" (dummy));
+
+ if (bar(1) != 2)
+ abort();
+
+ return 0;
+}
+
>
> Segher
