Tamar Christina <tamar.christ...@arm.com> writes: >> -----Original Message----- >> From: Richard Sandiford <richard.sandif...@arm.com> >> Sent: Wednesday, November 23, 2022 4:18 PM >> To: Tamar Christina <tamar.christ...@arm.com> >> Cc: gcc-patches@gcc.gnu.org; nd <n...@arm.com>; Richard Earnshaw >> <richard.earns...@arm.com>; Marcus Shawcroft >> <marcus.shawcr...@arm.com>; Kyrylo Tkachov <kyrylo.tkac...@arm.com> >> Subject: Re: [PATCH]AArch64 sve2: Fix expansion of division [PR107830] >> >> Tamar Christina <tamar.christ...@arm.com> writes: >> > Hi All, >> > >> > SVE has an actual division optab, and when using -Os we don't optimize >> > the division away. This means that we need to distinguish between a >> > div which we can optimize and one we cannot even during expansion. >> > >> > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues. >> > >> > Ok for master? >> > >> > Thanks, >> > Tamar >> > >> > gcc/ChangeLog: >> > >> > PR target/107830 >> > * config/aarch64/aarch64.cc >> > (aarch64_vectorize_can_special_div_by_constant): Check validity >> during >> > codegen phase as well. >> > >> > gcc/testsuite/ChangeLog: >> > >> > PR target/107830 >> > * gcc.target/aarch64/sve2/pr107830.c: New test. >> > >> > --- inline copy of patch -- >> > diff --git a/gcc/config/aarch64/aarch64.cc >> > b/gcc/config/aarch64/aarch64.cc index >> > >> 4176d7b046a126664360596b6db79a43e77ff76a..bee23625807af95d5ec15ad45 >> 702 >> > 961b2d7ab55d 100644 >> > --- a/gcc/config/aarch64/aarch64.cc >> > +++ b/gcc/config/aarch64/aarch64.cc >> > @@ -24322,12 +24322,15 @@ >> aarch64_vectorize_can_special_div_by_constant (enum tree_code code, >> > if ((flags & VEC_ANY_SVE) && !TARGET_SVE2) >> > return false; >> > >> > + wide_int val = wi::add (cst, 1); >> > + int pow = wi::exact_log2 (val); >> > + bool valid_p = pow == (int)(element_precision (vectype) / 2); >> > + /* SVE actually has a div operator, we we may have gotten here through >> > + that route. */ >> > if (in0 == NULL_RTX && in1 == NULL_RTX) >> > - { >> > - wide_int val = wi::add (cst, 1); >> > - int pow = wi::exact_log2 (val); >> > - return pow == (int)(element_precision (vectype) / 2); >> > - } >> > + return valid_p; >> > + else if (!valid_p) >> > + return false; >> >> Is this equivalent to: >> >> int pow = wi::exact_log2 (cst + 1); >> if (pow != (int) (element_precision (vectype) / 2)) >> return false; >> >> /* We can use the optimized pattern. */ >> if (in0 == NULL_RTX && in1 == NULL_RTX) >> return true; >> >> ? If so, I'd find that slightly easier to follow, but I realise it's >> personal taste. >> OK with that change if it works and you agree. >> >> While looking at this, I noticed that we ICE for: >> >> void f(unsigned short *restrict p1, unsigned int *restrict p2) >> { >> for (int i = 0; i < 16; ++i) >> { >> p1[i] /= 0xff; >> p2[i] += 1; >> } >> } >> >> for -march=armv8-a+sve2 -msve-vector-bits=512. I guess we need to filter >> out partial modes or (better) add support for them. Adding support for them >> probably requires changes to the underlying ADDHNB pattern. > > I've prevented the ice by checking if the expansion for the mode exists. I'd > like to > defer adding partial support because when I tried I had to modify some > iterators > as well and need to check that it's safe to do so.
Sounds good. > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues. > > Ok for master? > > Thanks, > Tamar > > gcc/ChangeLog: > > PR target/107830 > * config/aarch64/aarch64.cc > (aarch64_vectorize_can_special_div_by_constant): Check validity during > codegen phase as well. > > gcc/testsuite/ChangeLog: > > PR target/107830 > * gcc.target/aarch64/sve2/pr107830-1.c: New test. > * gcc.target/aarch64/sve2/pr107830-2.c: New test. > > --- inline copy of patch ---- > > diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc > index > 4176d7b046a126664360596b6db79a43e77ff76a..02aa1f34ac6155b877340d788c6d151b7c8d8bcd > 100644 > --- a/gcc/config/aarch64/aarch64.cc > +++ b/gcc/config/aarch64/aarch64.cc > @@ -24322,12 +24322,18 @@ aarch64_vectorize_can_special_div_by_constant (enum > tree_code code, > if ((flags & VEC_ANY_SVE) && !TARGET_SVE2) > return false; > > + wide_int val = wi::add (cst, 1); > + int pow = wi::exact_log2 (val); Does the: int pow = wi::exact_log2 (cst + 1); I suggested above not work? That seems easier to read IMO, since there are no other uses of "val". > + auto insn_code = maybe_code_for_aarch64_bitmask_udiv3 (TYPE_MODE > (vectype)); > + /* SVE actually has a div operator, we may have gotten here through > + that route. */ > + if (pow != (int)(element_precision (vectype) / 2) Formatting nit: should be a space after "(int)". OK with those changes, thanks. Richard > + || insn_code == CODE_FOR_nothing) > + return false; > + > + /* We can use the optimized pattern. */ > if (in0 == NULL_RTX && in1 == NULL_RTX) > - { > - wide_int val = wi::add (cst, 1); > - int pow = wi::exact_log2 (val); > - return pow == (int)(element_precision (vectype) / 2); > - } > + return true; > > if (!VECTOR_TYPE_P (vectype)) > return false; > diff --git a/gcc/testsuite/gcc.target/aarch64/sve2/pr107830-1.c > b/gcc/testsuite/gcc.target/aarch64/sve2/pr107830-1.c > new file mode 100644 > index > 0000000000000000000000000000000000000000..6d8ee3615fdb0083dbde1e45a2826fb681726139 > --- /dev/null > +++ b/gcc/testsuite/gcc.target/aarch64/sve2/pr107830-1.c > @@ -0,0 +1,13 @@ > +/* { dg-do compile } */ > +/* { dg-require-effective-target fopenmp } */ > +/* { dg-additional-options "-Os -fopenmp" } */ > + > +void > +f2 (int *a) > +{ > + unsigned int i; > + > +#pragma omp simd > + for (i = 0; i < 4; ++i) > + a[i / 3] -= 4; > +} > diff --git a/gcc/testsuite/gcc.target/aarch64/sve2/pr107830-2.c > b/gcc/testsuite/gcc.target/aarch64/sve2/pr107830-2.c > new file mode 100644 > index > 0000000000000000000000000000000000000000..4ec45d7a47e591263fa9acbfc7e6d3297e10a109 > --- /dev/null > +++ b/gcc/testsuite/gcc.target/aarch64/sve2/pr107830-2.c > @@ -0,0 +1,12 @@ > +/* { dg-do compile } */ > +/* { dg-additional-options "-O3 -msve-vector-bits=512" } */ > + > +void f(unsigned short *restrict p1, unsigned int *restrict p2) > +{ > + for (int i = 0; i < 16; ++i) > + { > + p1[i] /= 0xff; > + p2[i] += 1; > + } > +} > +