> Am 26.03.2025 um 09:15 schrieb Jakub Jelinek <ja...@redhat.com>:
>
> Hi!
>
> The following testcase is miscompiled since r14-8680 PR113560 changes.
> I've already tried to fix some of the issues caused by that change in
> r14-8823 PR113759, but apparently didn't get it right.
>
> The problem is that the r14-8680 changes sometimes set *type_out to
> a narrower type than the *new_rhs_out actually has (because it will
> handle stuff like _1 = rhs1 & 0xffff; and imply from that HImode type_out.
>
> Now, if in convert_mult_to_widen or convert_plusminus_to_widen we actually
> get optab for the modes we've asked for (i.e. with from_mode and to_mode),
> everything works fine, if the operands don't have the expected types,
> they are converted to those (for INTEGER_CSTs with fold_convert,
> otherwise with build_and_insert_cast).
> On the following testcase on aarch64 that is not the case, we ask
> for from_mode HImode and to_mode DImode, but get actual_mode SImode.
> The mult_rhs1 operand already has SImode and we change type1 to unsigned int
> and so no cast is actually done, except that the & 0xffff is lost that way.
>
> The following patch ensures that if we change typeN because of wider
> actual_mode (or because of a sign change), we first cast to the old
> typeN (if the r14-8680 code was encountered, otherwise it would have the
> same precision) and only then change it, and then perhaps cast again.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux and tested on the
> testcase with cross to aarch64-linux, where it results in the expected
> - add x19, x19, w0, uxtw 1
> + add x19, x19, w0, uxth 1
> difference. Ok for trunk?
Ok
Richard
> 2025-03-26 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/119417
> * tree-ssa-math-opts.cc (convert_mult_to_widen): Before changing
> typeN because actual_precision/from_unsignedN differs cast rhsN
> to typeN if it has a different type.
> (convert_plusminus_to_widen): Before changing
> typeN because actual_precision/from_unsignedN differs cast mult_rhsN
> to typeN if it has a different type.
>
> * gcc.dg/torture/pr119417.c: New test.
>
> --- gcc/tree-ssa-math-opts.cc.jj 2025-01-02 11:23:15.939524919 +0100
> +++ gcc/tree-ssa-math-opts.cc 2025-03-25 15:56:34.171411578 +0100
> @@ -2800,7 +2800,17 @@ convert_mult_to_widen (gimple *stmt, gim
> return false;
> if (actual_precision != TYPE_PRECISION (type1)
> || from_unsigned1 != TYPE_UNSIGNED (type1))
> - type1 = build_nonstandard_integer_type (actual_precision,
> from_unsigned1);
> + {
> + if (!useless_type_conversion_p (type1, TREE_TYPE (rhs1)))
> + {
> + if (TREE_CODE (rhs1) == INTEGER_CST)
> + rhs1 = fold_convert (type1, rhs1);
> + else
> + rhs1 = build_and_insert_cast (gsi, loc, type1, rhs1);
> + }
> + type1 = build_nonstandard_integer_type (actual_precision,
> + from_unsigned1);
> + }
> if (!useless_type_conversion_p (type1, TREE_TYPE (rhs1)))
> {
> if (TREE_CODE (rhs1) == INTEGER_CST)
> @@ -2810,7 +2820,17 @@ convert_mult_to_widen (gimple *stmt, gim
> }
> if (actual_precision != TYPE_PRECISION (type2)
> || from_unsigned2 != TYPE_UNSIGNED (type2))
> - type2 = build_nonstandard_integer_type (actual_precision,
> from_unsigned2);
> + {
> + if (!useless_type_conversion_p (type2, TREE_TYPE (rhs2)))
> + {
> + if (TREE_CODE (rhs2) == INTEGER_CST)
> + rhs2 = fold_convert (type2, rhs2);
> + else
> + rhs2 = build_and_insert_cast (gsi, loc, type2, rhs2);
> + }
> + type2 = build_nonstandard_integer_type (actual_precision,
> + from_unsigned2);
> + }
> if (!useless_type_conversion_p (type2, TREE_TYPE (rhs2)))
> {
> if (TREE_CODE (rhs2) == INTEGER_CST)
> @@ -3021,7 +3041,17 @@ convert_plusminus_to_widen (gimple_stmt_
> actual_precision = GET_MODE_PRECISION (actual_mode);
> if (actual_precision != TYPE_PRECISION (type1)
> || from_unsigned1 != TYPE_UNSIGNED (type1))
> - type1 = build_nonstandard_integer_type (actual_precision,
> from_unsigned1);
> + {
> + if (!useless_type_conversion_p (type1, TREE_TYPE (mult_rhs1)))
> + {
> + if (TREE_CODE (mult_rhs1) == INTEGER_CST)
> + mult_rhs1 = fold_convert (type1, mult_rhs1);
> + else
> + mult_rhs1 = build_and_insert_cast (gsi, loc, type1, mult_rhs1);
> + }
> + type1 = build_nonstandard_integer_type (actual_precision,
> + from_unsigned1);
> + }
> if (!useless_type_conversion_p (type1, TREE_TYPE (mult_rhs1)))
> {
> if (TREE_CODE (mult_rhs1) == INTEGER_CST)
> @@ -3031,7 +3061,17 @@ convert_plusminus_to_widen (gimple_stmt_
> }
> if (actual_precision != TYPE_PRECISION (type2)
> || from_unsigned2 != TYPE_UNSIGNED (type2))
> - type2 = build_nonstandard_integer_type (actual_precision,
> from_unsigned2);
> + {
> + if (!useless_type_conversion_p (type2, TREE_TYPE (mult_rhs2)))
> + {
> + if (TREE_CODE (mult_rhs2) == INTEGER_CST)
> + mult_rhs2 = fold_convert (type2, mult_rhs2);
> + else
> + mult_rhs2 = build_and_insert_cast (gsi, loc, type2, mult_rhs2);
> + }
> + type2 = build_nonstandard_integer_type (actual_precision,
> + from_unsigned2);
> + }
> if (!useless_type_conversion_p (type2, TREE_TYPE (mult_rhs2)))
> {
> if (TREE_CODE (mult_rhs2) == INTEGER_CST)
> --- gcc/testsuite/gcc.dg/torture/pr119417.c.jj 2025-03-25
> 16:03:42.895646634 +0100
> +++ gcc/testsuite/gcc.dg/torture/pr119417.c 2025-03-25 16:03:18.363976613
> +0100
> @@ -0,0 +1,24 @@
> +/* PR tree-optimization/119417 */
> +/* { dg-do run { target int32 } } */
> +
> +__attribute__((noipa)) void
> +foo (unsigned long long x)
> +{
> + if (x != 0)
> + __builtin_abort ();
> +}
> +
> +unsigned v = 0x10000;
> +
> +int
> +main ()
> +{
> + unsigned long long a = 0;
> + while (1)
> + {
> + a = a + ((v & 0xFFFF) * 2);
> + foo (a);
> + if (v)
> + break;
> + }
> +}
>
> Jakub
>
