Hi!
As the following testcase shows, we emit a -Wpsabi note about argument
passing change since GCC 9, but in reality the ABI didn't change.
The alignment is 8 bits in GCC < 9 and 32 bits in GCC >= 9 and
the aarch64_function_arg_alignment returns in that case:
return MIN (MAX (alignment, PARM_BOUNDARY), STACK_BOUNDARY);
so when both the old and new alignment are smaller or equal to PARM_BOUNDARY
(or both are larger than STACK_BOUNDARY, just in theory), even when the new
one is bigger, it doesn't change the argument passing.
So, the following patch changes aarch64_function_arg_alignment to tell the
callers the exact old alignmentm so that they can test it if needed.
The other aarch64_function_arg_alignment callers either check the
alignment for equality against 16-byte alignment (when old alignment was
smaller than that and the new one is 16-byte, we want to emit -Wpsabi
in all the cases) or the va_arg case which I think is ok now too.
Bootstrapped/regtested on aarch64-linux, ok for trunk?
2021-03-18 Jakub Jelinek <ja...@redhat.com>
PR target/91710
* config/aarch64/aarch64.c (aarch64_function_arg_alignment): Change
abi_break argument from bool * to unsigned *, store there the pre-GCC 9
alignment.
(aarch64_layout_arg, aarch64_gimplify_va_arg_expr): Adjust callers.
(aarch64_function_arg_regno_p): Likewise. Only emit -Wpsabi note if
the old and new alignment after applying MIN/MAX to it is different.
* gcc.target/aarch64/pr91710.c: New test.
--- gcc/config/aarch64/aarch64.c.jj 2021-03-18 15:14:51.721425223 +0100
+++ gcc/config/aarch64/aarch64.c 2021-03-18 16:35:04.437115447 +0100
@@ -5938,9 +5938,9 @@ aarch64_vfp_is_call_candidate (cumulativ
static unsigned int
aarch64_function_arg_alignment (machine_mode mode, const_tree type,
- bool *abi_break)
+ unsigned int *abi_break)
{
- *abi_break = false;
+ *abi_break = 0;
if (!type)
return GET_MODE_ALIGNMENT (mode);
@@ -5982,7 +5982,7 @@ aarch64_function_arg_alignment (machine_
if (bitfield_alignment > alignment)
{
- *abi_break = true;
+ *abi_break = alignment;
return bitfield_alignment;
}
@@ -6004,7 +6004,7 @@ aarch64_layout_arg (cumulative_args_t pc
int ncrn, nvrn, nregs;
bool allocate_ncrn, allocate_nvrn;
HOST_WIDE_INT size;
- bool abi_break;
+ unsigned int abi_break;
/* We need to do this once per argument. */
if (pcum->aapcs_arg_processed)
@@ -6322,14 +6322,19 @@ aarch64_function_arg_regno_p (unsigned r
static unsigned int
aarch64_function_arg_boundary (machine_mode mode, const_tree type)
{
- bool abi_break;
+ unsigned int abi_break;
unsigned int alignment = aarch64_function_arg_alignment (mode, type,
&abi_break);
+ alignment = MIN (MAX (alignment, PARM_BOUNDARY), STACK_BOUNDARY);
if (abi_break & warn_psabi)
- inform (input_location, "parameter passing for argument of type "
- "%qT changed in GCC 9.1", type);
+ {
+ abi_break = MIN (MAX (abi_break, PARM_BOUNDARY), STACK_BOUNDARY);
+ if (alignment != abi_break)
+ inform (input_location, "parameter passing for argument of type "
+ "%qT changed in GCC 9.1", type);
+ }
- return MIN (MAX (alignment, PARM_BOUNDARY), STACK_BOUNDARY);
+ return alignment;
}
/* Implement TARGET_GET_RAW_RESULT_MODE and TARGET_GET_RAW_ARG_MODE. */
@@ -16616,7 +16621,7 @@ aarch64_gimplify_va_arg_expr (tree valis
f_stack, NULL_TREE);
size = int_size_in_bytes (type);
- bool abi_break;
+ unsigned int abi_break;
align
= aarch64_function_arg_alignment (mode, type, &abi_break) / BITS_PER_UNIT;
--- gcc/testsuite/gcc.target/aarch64/pr91710.c.jj 2021-03-18
16:42:33.529232710 +0100
+++ gcc/testsuite/gcc.target/aarch64/pr91710.c 2021-03-18 16:42:07.271518121
+0100
@@ -0,0 +1,16 @@
+/* PR target/91710 */
+/* { dg-do compile } */
+
+struct S { unsigned int i:4; };
+
+unsigned int test1(struct S s) { /* { dg-bogus "parameter passing for
argument of type" } */
+ return s.i;
+}
+
+unsigned int test2(unsigned x, struct S s) { /* { dg-bogus "parameter
passing for argument of type" } */
+ return x - s.i;
+}
+
+unsigned int test3(unsigned x, unsigned y, struct S s) { /* { dg-bogus
"parameter passing for argument of type" } */
+ return x - y - s.i;
+}
Jakub
