| Message ID | 20240130184306.3005276-1-quic_apinski@quicinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | aarch64: -mstrict-align vs __arm_data512_t [PR113657] | expand |
Andrew Pinski <quic_apinski@quicinc.com> writes: > 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> > --- > gcc/config/aarch64/aarch64-simd.md | 16 ++++++++++++---- > .../gcc.target/aarch64/acle/ls64_strict_align.c | 7 +++++++ > 2 files changed, 19 insertions(+), 4 deletions(-) > create mode 100644 gcc/testsuite/gcc.target/aarch64/acle/ls64_strict_align.c > > diff --git a/gcc/config/aarch64/aarch64-simd.md b/gcc/config/aarch64/aarch64-simd.md > index 7a6b4430112..0b4b37115d6 100644 > --- a/gcc/config/aarch64/aarch64-simd.md > +++ b/gcc/config/aarch64/aarch64-simd.md > @@ -8221,14 +8221,22 @@ (define_split > || (memory_operand (operands[0], V8DImode) > && register_operand (operands[1], V8DImode))) > { > + int increment = 16; > + machine_mode mode = TImode; > + /* For strict alignment, use DImode to avoid "unalign" subreg. */ > + if (STRICT_ALIGNMENT) > + { > + mode = DImode; > + increment = 8; > + } Sorry for the trivial change, but I think this would be slightly neater as: /* V8DI only guarantees 8-byte alignment, whereas TImode requires 16. */ auto mode = STRICT_ALIGNMENT ? DImode : TImode; int increment = GET_MODE_SIZE (mode); OK with that change, thanks. Richard > 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 00000000000..bf49ac76f78 > --- /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; }
diff --git a/gcc/config/aarch64/aarch64-simd.md b/gcc/config/aarch64/aarch64-simd.md index 7a6b4430112..0b4b37115d6 100644 --- a/gcc/config/aarch64/aarch64-simd.md +++ b/gcc/config/aarch64/aarch64-simd.md @@ -8221,14 +8221,22 @@ (define_split || (memory_operand (operands[0], V8DImode) && register_operand (operands[1], V8DImode))) { + int increment = 16; + machine_mode mode = TImode; + /* For strict alignment, use DImode to avoid "unalign" subreg. */ + if (STRICT_ALIGNMENT) + { + mode = DImode; + increment = 8; + } 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 00000000000..bf49ac76f78 --- /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; }
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> --- gcc/config/aarch64/aarch64-simd.md | 16 ++++++++++++---- .../gcc.target/aarch64/acle/ls64_strict_align.c | 7 +++++++ 2 files changed, 19 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/gcc.target/aarch64/acle/ls64_strict_align.c