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* [gcc r14-8671] aarch64: -mstrict-align vs __arm_data512_t [PR113657]
@ 2024-02-01 0:19 Andrew Pinski
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From: Andrew Pinski @ 2024-02-01 0:19 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:dbf847d2c8d1c910948ba34c9338939c67323273
commit r14-8671-gdbf847d2c8d1c910948ba34c9338939c67323273
Author: Andrew Pinski <quic_apinski@quicinc.com>
Date: Tue Jan 30 00:50:56 2024 -0800
aarch64: -mstrict-align vs __arm_data512_t [PR113657]
After r14-1187-gd6b756447cd58b, simplify_gen_subreg can return
NULL for "unaligned" memory subreg. Since V8DI has an alignment of 8 bytes,
using TImode causes simplify_gen_subreg to return NULL.
This fixes the issue by using DImode instead for the loop. And then we will have
later on the STP/LDP pass combine it back into STP/LDP if needed.
Since strict align is less important (usually used for firmware and early boot only),
not doing LDP/STP here is ok.
Built and tested for aarch64-linux-gnu with no regressions.
PR target/113657
gcc/ChangeLog:
* config/aarch64/aarch64-simd.md (split for movv8di):
For strict aligned mode, use DImode instead of TImode.
gcc/testsuite/ChangeLog:
* gcc.target/aarch64/acle/ls64_strict_align.c: New test.
Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
Diff:
---
gcc/config/aarch64/aarch64-simd.md | 11 +++++++----
gcc/testsuite/gcc.target/aarch64/acle/ls64_strict_align.c | 7 +++++++
2 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/gcc/config/aarch64/aarch64-simd.md b/gcc/config/aarch64/aarch64-simd.md
index f036f6ce997d..f8bb973a278c 100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -8221,14 +8221,17 @@
|| (memory_operand (operands[0], V8DImode)
&& register_operand (operands[1], V8DImode)))
{
+ /* V8DI only guarantees 8-byte alignment, whereas TImode requires 16. */
+ auto mode = STRICT_ALIGNMENT ? DImode : TImode;
+ int increment = GET_MODE_SIZE (mode);
std::pair<rtx, rtx> last_pair = {};
- for (int offset = 0; offset < 64; offset += 16)
+ for (int offset = 0; offset < 64; offset += increment)
{
std::pair<rtx, rtx> pair = {
- simplify_gen_subreg (TImode, operands[0], V8DImode, offset),
- simplify_gen_subreg (TImode, operands[1], V8DImode, offset)
+ simplify_gen_subreg (mode, operands[0], V8DImode, offset),
+ simplify_gen_subreg (mode, operands[1], V8DImode, offset)
};
- if (register_operand (pair.first, TImode)
+ if (register_operand (pair.first, mode)
&& reg_overlap_mentioned_p (pair.first, pair.second))
last_pair = pair;
else
diff --git a/gcc/testsuite/gcc.target/aarch64/acle/ls64_strict_align.c b/gcc/testsuite/gcc.target/aarch64/acle/ls64_strict_align.c
new file mode 100644
index 000000000000..bf49ac76f78b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/acle/ls64_strict_align.c
@@ -0,0 +1,7 @@
+/* { dg-do compile } */
+/* { dg-options "-mstrict-align" } */
+/* PR target/113657 */
+
+#pragma GCC target "+ls64"
+#pragma GCC aarch64 "arm_acle.h"
+__arm_data512_t foo(__arm_data512_t* ptr) { return *ptr; }
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