On Wed, Aug 12, 2026 at 12:30 AM Richard Biener <[email protected]> wrote: > > On Tue, Aug 11, 2026 at 5:00 PM Andrea Pinski > <[email protected]> wrote: > > > > This adds some extra checks to see if we can remove the casts > > for signed integer overflow reasons while doing a negative. > > This is needed more due to the recent patch which adds them > > in some cases. > > Can't you use expr_not_equal_to (..., INT_MIN)?
I didn't know expr_not_equal_to existed but yes we can. > > > Bootstrapped and tested on x86_64-linux-gnu. > > > > PR tree-optimization/107765 > > > > gcc/ChangeLog: > > > > * match.pd (`(cast)-(cast)a`): Expand to use ranger > > to see if we can remove the casts. > > > > gcc/testsuite/ChangeLog: > > > > * gcc.dg/tree-ssa/neg-cast-1.c: New test. > > * gcc.dg/tree-ssa/neg-cast-4.c: New test. > > > > Signed-off-by: Andrea Pinski <[email protected]> > > --- > > gcc/match.pd | 37 ++++++++++++++++++---- > > gcc/testsuite/gcc.dg/tree-ssa/neg-cast-1.c | 23 ++++++++++++++ > > gcc/testsuite/gcc.dg/tree-ssa/neg-cast-4.c | 16 ++++++++++ > > 3 files changed, 69 insertions(+), 7 deletions(-) > > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/neg-cast-1.c > > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/neg-cast-4.c > > > > diff --git a/gcc/match.pd b/gcc/match.pd > > index 751f5571183..8de356b102c 100644 > > --- a/gcc/match.pd > > +++ b/gcc/match.pd > > @@ -1233,15 +1233,38 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > > show up. Else it is safe if the negation is done in an unsigned type. > > Note the outer cast cannot be a boolean type as the only valid values > > are 0,-1/1 (depending on the signedness of the boolean) and the negative > > - is there to get the correct value. */ > > + is there to get the correct value. > > + Also handle the case where we */ > > (simplify > > - (convert (negate:s@1 (convert:s @0))) > > + (convert (negate:s@1 (convert:s@ic @0))) > > (if (INTEGRAL_TYPE_P (type) > > - && tree_nop_conversion_p (type, TREE_TYPE (@1)) > > - && (TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (@0)) > > - || TYPE_UNSIGNED (type)) > > - && TREE_CODE (type) != BOOLEAN_TYPE) > > - (negate (convert @0)))) > > + && tree_nop_conversion_p (type, TREE_TYPE (@1))) > > + (with { > > + bool can_handle = false; > > +#if GIMPLE > > + int_range_max vr; > > +#endif > > + if ((TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (@0)) > > + || TYPE_UNSIGNED (type)) > > + && TREE_CODE (type) != BOOLEAN_TYPE) > > + can_handle = true; > > + else if (wi::ges_p (tree_nonzero_bits (@ic), 0)) > > + can_handle = true; > > +#if GIMPLE > > + /* If we know that @0 does not contain signed max, then the > > + conversion can be removed. */ > > + else if (TREE_CODE (@0) == SSA_NAME > > + && types_match (type, TREE_TYPE (@0)) > > + && get_range_query (cfun)->range_of_expr (vr, @0) > > + && !vr.undefined_p ()) > > + { > > + tree stype = signed_type_for (type); > > + can_handle = !vr.contains_p (wi::min_value (stype)); > > + } > > +#endif > > + } > > + (if (can_handle) > > + (negate (convert @0)))))) > > > > (for op (negate abs) > > /* Simplify cos(-x) and cos(|x|) -> cos(x). Similarly for cosh. */ > > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/neg-cast-1.c > > b/gcc/testsuite/gcc.dg/tree-ssa/neg-cast-1.c > > new file mode 100644 > > index 00000000000..ec5d0e15251 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.dg/tree-ssa/neg-cast-1.c > > @@ -0,0 +1,23 @@ > > +/* { dg-do compile } */ > > +/* { dg-options "-O2 -fdump-tree-optimized -fdump-tree-cddce1" } */ > > +/* PR tree-optimization/107765 */ > > + > > +int a(int input) > > +{ > > + if (input == -__INT_MAX__-1) return 1; > > + unsigned t = input; > > + int tt = -t; > > + return tt == -input; > > +} > > + > > +int b(int input) > > +{ > > + if (input == -__INT_MAX__-1) __builtin_trap(); > > + unsigned t = input; > > + int tt = -t; > > + return tt; > > +} > > + > > +/* { dg-final { scan-tree-dump "return 1" "optimized" } } */ > > +/* { dg-final { scan-tree-dump-not "\\(unsigned int\\)" "cddce1" } } */ > > +/* { dg-final { scan-tree-dump-not "\\(int\\)" "cddce1" } } */ > > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/neg-cast-4.c > > b/gcc/testsuite/gcc.dg/tree-ssa/neg-cast-4.c > > new file mode 100644 > > index 00000000000..fe3fe6a2ecc > > --- /dev/null > > +++ b/gcc/testsuite/gcc.dg/tree-ssa/neg-cast-4.c > > @@ -0,0 +1,16 @@ > > +/* { dg-do compile } */ > > +/* { dg-options "-O2 -fdump-tree-phiopt2-details -fdump-tree-optimized" } > > */ > > +/* PR tree-optimization/107765 */ > > + > > +int b(int input) > > +{ > > + if (input == -__INT_MAX__-1) return input; > > + unsigned t = input; > > + int tt = -t; > > + return tt; > > +} > > + > > +/* { dg-final { scan-tree-dump-not "if " "optimized" } } */ > > +/* { dg-final { scan-tree-dump-times "\\(unsigned int\\)" 1 "optimized" } > > } */ > > +/* { dg-final { scan-tree-dump-times "\\(int\\)" 1 "optimized" } } */ > > +/* { dg-final { scan-tree-dump-times "converted to straightline code" 1 > > "phiopt2" } } */ > > -- > > 2.43.0 > >
