AMD General Hi
> -----Original Message----- > From: Andrea Pinski <[email protected]> > Sent: Friday, August 14, 2026 11:43 AM > To: Roy, Reshma <[email protected]> > Cc: [email protected]; Kumar, Venkataramanan > <[email protected]> > Subject: Re: [PATCH v2] match.pd: Fold umin(a, 1) | umin(b, 1) into umin(a | > b, 1) > [PR126646] > > Caution: This message originated from an External Source. Use proper caution > when opening attachments, clicking links, or responding. > > > On Thu, Aug 13, 2026 at 10:28 PM <[email protected]> wrote: > > > > From: Reshma Roy <[email protected]> > > > > gcc/ChangeLog: > > > > PR tree-optimization/126646 > > * match.pd: Fold umin(a, 1) | umin(b, 1) into umin(a | b, 1). > > > > gcc/testsuite/ChangeLog: > > > > * gcc.dg/tree-ssa/pr126646-1.c: New test. > > * gcc.dg/tree-ssa/pr126646-2.c: New test. > > Ok, see below about being ok about the testcase. Committed to gcc trunk at https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b190388bad47b1d3507abd52dc2a07f39a899984 regards, Venkat. > > > > > --- > > Hi, > > The patch is updated as per the comments and added a new test case for > > the same. My comments are added inline to the email. > > > > Bootstrapped and tested on x86_64-linux > > > > > -----Original Message----- > > > From: Andrea Pinski <[email protected]> > > > Sent: Wednesday, August 12, 2026 9:59 AM > > > To: Roy, Reshma <[email protected]> > > > Cc: [email protected]; Kumar, Venkataramanan > > > <[email protected]> > > > Subject: Re: [PATCH] match.pd: Fold umin(a, 1) | umin(b, 1) into > > > umin(a | b, 1) [PR126646] > > > > > > [You don't often get email from [email protected]. > > > Learn why this is important at > > > https://aka.ms/LearnAboutSenderIdentification ] > > > > > > Caution: This message originated from an External Source. Use proper > > > caution when opening attachments, clicking links, or responding. > > > > > > > > > On Tue, Aug 11, 2026 at 8:50 PM <[email protected]> wrote: > > > > > > > > From: Reshma Roy <[email protected]> > > > > > > > > gcc/ChangeLog: > > > > > > > > PR tree-optimization/126646 > > > > * match.pd: Fold umin(a, 1) | umin(b, 1) into umin(a | b, 1). > > > > > > > > gcc/testsuite/ChangeLog: > > > > > > > > * gcc.dg/tree-ssa/pr126646-1.c: New test. > > > > --- > > > > > > > > Hi, > > > > This patch fixes the missed optimization opportunity reported in > > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126646. > > > > For the following snippet of code, gcc generates 2 MIN_EXPR. > > > > unsigned f(unsigned a, unsigned b) > > > > { > > > > unsigned t = 1; > > > > a = a < t ? a : t; > > > > b = b < t ? b : t; > > > > return a | b; > > > > } > > > > But this can be optimized with just one MIN_EXPR since > > > > umin(a,1) | umin(b,1) can be simplified to umin(a|b, 1). > > > > > > > > Bootstrapped and tested on x86_64-linux. > > > > > > > > Thanks, > > > > Reshma > > > > > > > > gcc/match.pd | 5 +++++ > > > > gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c | 15 +++++++++++++++ > > > > 2 files changed, 20 insertions(+) create mode 100644 > > > > gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c > > > > > > > > diff --git a/gcc/match.pd b/gcc/match.pd index > > > > 50e73177022..7347b83ec4f 100644 > > > > --- a/gcc/match.pd > > > > +++ b/gcc/match.pd > > > > @@ -4860,6 +4860,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > > > > (bit_not (minmax:cs (bit_not @0) @1)) > > > > (maxmin @0 (bit_not @1)))) > > > > > > > > +/* umin (a, 1) | umin (b, 1) -> umin (a | b, 1). */ (simplify > > > > + (bit_ior (min @0 integer_onep@2) (min @1 @2)) > > > > + (if (TYPE_UNSIGNED (type)) > > > > > > Instead of TYPE_UNSIGNED here; I think it might be a good idea to > > > use tree_expr_nonnegative_p on both @0 and @1.. > > > tree_expr_nonnegative_p does return true for TYPE_UNSIGNED already > > > but it also returns true when the argument is known to be zero or > > > positive. > > Agreed, updated to use tree_expr_nonnegative_p (@0) && > > tree_expr_nonnegative_p (@1). This is strictly more general as it > > covers unsigned types (where tree_expr_nonnegative_p returns true by > > definition) and also signed types when the operands are non-negative. > > > > > > This allows for say: > > > ``` > > > int f(int a, int b) > > > { > > > int c = 0; > > > if (a >= 0 && b >= 0) > > > c = (a > 1 ? 1 : a) | (b > 1 ? 1 : b); > > > return c; > > > } > > > ``` > > Understood the test case scenario. But the above test case doesn't > > apply the new guard in practice because by the time match.pd sees the > > MIN_EXPRs, the condition a >= 0 && b >= 0 has already been folded into > > (a | b) >= 0. The dominating condition is now on the combined OR, so > > tree_expr_nonnegative_p on a and b individually can't prove > > non-negativity. Hence I have added a different test case > > (pr126646-2.c) that uses __builtin_abs, where non-negativity is > > implied in the expression itself. Hope that is fine. Let me know your > > thoughts. > > Yes, the different testcase using abs is fine. I forgot the ranger is NOT > always > enabled for forwprop so it is not always used for tree_expr_nonnegative_p; > instead tree_expr_nonnegative_p will use the global range. That is something > which I have been thinking about changing but I always get side tracked. > > > > > > > Which then should optimize to just: > > > _10 = a_6(D) | b_7(D); > > > c_8 = MIN_EXPR <_10, 1>; > > > _11 = MAX_EXPR <c_8, 0>; > > > > > > > > > Thanks, > > > Andrea > > > > > > > + (min (bit_ior @0 @1) @2))) > > > > /* MIN (X, Y) == X -> X <= Y */ > > > > /* MIN (X, Y) < X -> X > Y */ > > > > /* MIN (X, Y) >= X -> X <= Y */ > > > > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c > > > > b/gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c > > > > new file mode 100644 > > > > index 00000000000..447a1739b5f > > > > --- /dev/null > > > > +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c > > > > @@ -0,0 +1,15 @@ > > > > +/* { dg-do compile } */ > > > > +/* { dg-options "-O2 -fdump-tree-optimized" } */ > > > > + > > > > +/* The test case should produce only one min expr. */ > > > > +/* umin(a,1) | umin(b,1) -> umin(a|b, 1). */ > > > > + > > > > +unsigned min_or (unsigned a, unsigned b) { > > > > + unsigned t = 1; > > > > + a = a < t ? a : t; > > > > + b = b < t ? b : t; > > > > + return a | b; > > > > +} > > > > + > > > > +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "optimized" } } > > > > +*/ > > > > -- > > > > 2.34.1 > > > > > > > > Thanks, > > Reshma > > > > > > gcc/match.pd | 5 +++++ > > gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c | 15 +++++++++++++++ > > gcc/testsuite/gcc.dg/tree-ssa/pr126646-2.c | 13 +++++++++++++ > > 3 files changed, 33 insertions(+) > > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c > > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr126646-2.c > > > > diff --git a/gcc/match.pd b/gcc/match.pd index > > 5fc89426880..be2bc0dd8df 100644 > > --- a/gcc/match.pd > > +++ b/gcc/match.pd > > @@ -4887,6 +4887,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > > (bit_not (minmax:cs (bit_not @0) @1)) > > (maxmin @0 (bit_not @1)))) > > > > +/* umin (a, 1) | umin (b, 1) -> umin (a | b, 1). */ (simplify > > + (bit_ior (min @0 integer_onep@2) (min @1 @2)) > > + (if (tree_expr_nonnegative_p (@0) && tree_expr_nonnegative_p (@1)) > > + (min (bit_ior @0 @1) @2))) > > /* MIN (X, Y) == X -> X <= Y */ > > /* MIN (X, Y) < X -> X > Y */ > > /* MIN (X, Y) >= X -> X <= Y */ > > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c > > b/gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c > > new file mode 100644 > > index 00000000000..447a1739b5f > > --- /dev/null > > +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c > > @@ -0,0 +1,15 @@ > > +/* { dg-do compile } */ > > +/* { dg-options "-O2 -fdump-tree-optimized" } */ > > + > > +/* The test case should produce only one min expr. */ > > +/* umin(a,1) | umin(b,1) -> umin(a|b, 1). */ > > + > > +unsigned min_or (unsigned a, unsigned b) { > > + unsigned t = 1; > > + a = a < t ? a : t; > > + b = b < t ? b : t; > > + return a | b; > > +} > > + > > +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "optimized" } } */ > > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr126646-2.c > > b/gcc/testsuite/gcc.dg/tree-ssa/pr126646-2.c > > new file mode 100644 > > index 00000000000..3b47eee9656 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr126646-2.c > > @@ -0,0 +1,13 @@ > > +/* { dg-do compile } */ > > +/* { dg-options "-O2 -fdump-tree-optimized" } */ > > + > > +int f (int a, int b) > > +{ > > + int x = __builtin_abs (a); > > + int y = __builtin_abs (b); > > + int p = x < 1 ? x : 1; > > + int q = y < 1 ? y : 1; > > + return p | q; > > +} > > + > > +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "optimized" } } */ > > -- > > 2.34.1 > >
