On Mon, Aug 10, 2026 at 5:47 PM H.J. Lu <[email protected]> wrote: > > On Sun, Aug 9, 2026 at 6:19 AM Andrew Pinski <[email protected]> wrote: > > > > On Tue, Aug 4, 2026 at 3:00 AM <[email protected]> wrote: > > > > > > From: Kyrylo Tkachov <[email protected]> > > > > > > The rule folding (type) minmax ((wide_type) a, (wide_type) b) to > > > minmax (a, b) is restricted to scalars. Extension is monotone, so it > > > commutes with the comparison and the outer truncation is exact, and the > > > argument is lanewise, so it holds for vectors unchanged. > > > > > > The vector case additionally needs the narrow operation to be available, > > > otherwise vector lowering would scalarise what used to be a single wide > > > instruction. > > > > > > typedef int v2si __attribute__((vector_size (8))); > > > typedef long v2di __attribute__((vector_size (16))); > > > v2si h (v2si a, v2si b) > > > { > > > v2di x = __builtin_convertvector (a, v2di); > > > v2di y = __builtin_convertvector (b, v2di); > > > return __builtin_convertvector (x < y ? x : y, v2si); > > > } > > > > > > aarch64 -O3 before: > > > > > > sshll v0.2d, v0.2s, 0 > > > sshll v1.2d, v1.2s, 0 > > > cmgt v2.2d, v1.2d, v0.2d > > > bsl v2.16b, v0.16b, v1.16b > > > xtn v0.2s, v2.2d > > > > > > after: > > > > > > smin v0.2s, v0.2s, v1.2s > > > > > > Require the wide vector MIN or MAX to have one use. A shared wide > > > result would otherwise gain a second narrow operation. > > > > > > Bootstrapped and tested on aarch64-none-linux-gnu. > > > Ok for trunk? > > > Thanks, > > > Kyrill > > > > > > gcc/ChangeLog: > > > > > > * match.pd ((type) minmax ((wide_type) a, (wide_type) b)): Accept > > > vector types, using element_precision and requiring the narrow > > > operation to be supported. > > > > > > gcc/testsuite/ChangeLog: > > > > > > * g++.dg/tree-ssa/vec-narrow-1.C: New test. > > > * g++.dg/tree-ssa/vec-narrow-minmax-2.C: New test. > > > > > > Signed-off-by: Kyrylo Tkachov <[email protected]> > > > --- > > > gcc/match.pd | 20 +++++++++++++------ > > > gcc/testsuite/g++.dg/tree-ssa/vec-narrow-1.C | 11 ++++++++++ > > > .../g++.dg/tree-ssa/vec-narrow-minmax-2.C | 18 +++++++++++++++++ > > > 3 files changed, 43 insertions(+), 6 deletions(-) > > > create mode 100644 gcc/testsuite/g++.dg/tree-ssa/vec-narrow-1.C > > > create mode 100644 gcc/testsuite/g++.dg/tree-ssa/vec-narrow-minmax-2.C > > > > > > diff --git a/gcc/match.pd b/gcc/match.pd > > > index e0ec2626842..adbdda91b51 100644 > > > --- a/gcc/match.pd > > > +++ b/gcc/match.pd > > > @@ -4649,17 +4649,25 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > > > > > > /* (type) minmax ((wide_type) a, (wide_type) b) -> minmax (a, b) > > > when type matches the type of a and b, and wide_type is a wider > > > - type with the same signedness as type. */ > > > + type with the same signedness as type. Extension is monotone, so it > > > + commutes with the comparison, and the truncation is then exact. The > > > + same holds lanewise for a vector, where the narrow operation has to be > > > + available so that lowering does not scalarise it. The wide operation > > > + must become dead before a narrow vector operation is introduced. */ > > > (for minmax (min max) > > > + MINMAX (MIN_EXPR MAX_EXPR) > > > (simplify > > > - (convert (minmax:c (convert@2 @0) (convert@3 @1))) > > > - (if (INTEGRAL_TYPE_P (type) > > > - && INTEGRAL_TYPE_P (TREE_TYPE (@2)) > > > + (convert (minmax:c@4 (convert@2 @0) (convert@3 @1))) > > > + (if (ANY_INTEGRAL_TYPE_P (type) > > > + && ANY_INTEGRAL_TYPE_P (TREE_TYPE (@2)) > > > && types_match (type, TREE_TYPE (@0)) > > > && types_match (type, TREE_TYPE (@1)) > > > && types_match (TREE_TYPE (@2), TREE_TYPE (@3)) > > > - && TYPE_PRECISION (TREE_TYPE (@2)) > TYPE_PRECISION (type) > > > - && TYPE_UNSIGNED (TREE_TYPE (@2)) == TYPE_UNSIGNED (type)) > > > + && element_precision (TREE_TYPE (@2)) > element_precision (type) > > > + && TYPE_UNSIGNED (TREE_TYPE (@2)) == TYPE_UNSIGNED (type) > > > + && (!VECTOR_TYPE_P (type) > > > + || (single_use (@4) > > > + && target_supports_op_p (type, MINMAX, optab_vector)))) > > > (minmax @0 @1)))) > > > > > > /* max (a, a + CST) -> a + CST where CST is positive. */ > > > diff --git a/gcc/testsuite/g++.dg/tree-ssa/vec-narrow-1.C > > > b/gcc/testsuite/g++.dg/tree-ssa/vec-narrow-1.C > > > new file mode 100644 > > > index 00000000000..de738e33c30 > > > --- /dev/null > > > +++ b/gcc/testsuite/g++.dg/tree-ssa/vec-narrow-1.C > > > @@ -0,0 +1,11 @@ > > > +// { dg-do compile } > > > +// { dg-options "-O2 -fdump-tree-optimized" } > > > +// Extension is monotone, so it commutes with the comparison and the > > > outer > > > +// truncation is exact. The argument is lanewise, so a widened vector > > > +// MIN/MAX feeding a truncating conversion narrows. > > > +typedef int v2si __attribute__((vector_size (8))); > > > +typedef long long v2di __attribute__((vector_size (16))); > > > +v2si f (v2si a, v2si b) > > > +{ v2di x = __builtin_convertvector (a, v2di), y = > > > __builtin_convertvector (b, v2di); > > > + return __builtin_convertvector (x < y ? x : y, v2si); } > > > +// { dg-final { scan-tree-dump-not "vector\\(2\\) long" "optimized" } } > > > > > > This testcase fails on x86_64. > > This is needed: > > diff --git a/gcc/testsuite/g++.dg/tree-ssa/vec-narrow-minmax-2.C > b/gcc/testsuite/g++.dg/tree-ssa/vec-narrow-minmax-2.C > index d7fb7f06f16..f51730f08a7 100644 > --- a/gcc/testsuite/g++.dg/tree-ssa/vec-narrow-minmax-2.C > +++ b/gcc/testsuite/g++.dg/tree-ssa/vec-narrow-minmax-2.C > @@ -1,5 +1,6 @@ > // { dg-do compile } > // { dg-options "-O2 -fdump-tree-optimized" } > +// { dg-additional-options "-mavx512vl -mavx512dq" { target { > i?86-*-* x86_64-*-* } } } > > typedef int v2si __attribute__((vector_size (8))); > typedef long long v2di __attribute__((vector_size (16))); > > I am checking it in.
These instructions are in SSE4.1. But due to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126767 -msse4 is needed. > > > diff --git a/gcc/testsuite/g++.dg/tree-ssa/vec-narrow-minmax-2.C > > > b/gcc/testsuite/g++.dg/tree-ssa/vec-narrow-minmax-2.C > > > new file mode 100644 > > > index 00000000000..d7fb7f06f16 > > > --- /dev/null > > > +++ b/gcc/testsuite/g++.dg/tree-ssa/vec-narrow-minmax-2.C > > > @@ -0,0 +1,18 @@ > > > +// { dg-do compile } > > > +// { dg-options "-O2 -fdump-tree-optimized" } > > > + > > > +typedef int v2si __attribute__((vector_size (8))); > > > +typedef long long v2di __attribute__((vector_size (16))); > > > + > > > +v2si > > > +f (v2si a, v2si b, v2di *p) > > > +{ > > > + v2di x = __builtin_convertvector (a, v2di); > > > + v2di y = __builtin_convertvector (b, v2di); > > > + v2di z = x < y ? x : y; > > > + *p = z; > > > + return __builtin_convertvector (z, v2si); > > > +} > > > + > > > +// A shared wide MIN must not gain a second narrow MIN. > > > +// { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "optimized" } } > > > -- > > > 2.50.1 (Apple Git-155) > > > > > > > -- > H.J. -- H.J.
