RE: [COMMITTED] Fold: Fix up merge_truthop_with_opposite_arm for NaNs [PR95351]

["Andrew Pinski (QUIC)" <quic_apinski@quicinc.com>]

> -----Original Message-----
> From: Andrew Pinski (QUIC) <quic_apinski@quicinc.com>
> Sent: Sunday, March 10, 2024 7:58 PM
> To: gcc-patches@gcc.gnu.org
> Cc: Andrew Pinski (QUIC) <quic_apinski@quicinc.com>
> Subject: [COMMITTED] Fold: Fix up merge_truthop_with_opposite_arm for
> NaNs [PR95351]
> 
> The problem here is that merge_truthop_with_opposite_arm would use the
> type of the result of the comparison rather than the operands of the
> comparison to figure out if we are honoring NaNs.
> This fixes that oversight and now we get the correct results in this case.
> 
> Committed as obvious after a bootstrap/test on x86_64-linux-gnu.

Committed to the GCC 13 branch too.

Thanks,
Andrew

> 
> 	PR middle-end/95351
> 
> gcc/ChangeLog:
> 
> 	* fold-const.cc (merge_truthop_with_opposite_arm): Use
> 	the type of the operands of the comparison and not the type
> 	of the comparison.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.dg/float_opposite_arm-1.c: New test.
> 
> Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
> ---
>  gcc/fold-const.cc                           |  3 ++-
>  gcc/testsuite/gcc.dg/float_opposite_arm-1.c | 17 +++++++++++++++++
>  2 files changed, 19 insertions(+), 1 deletion(-)  create mode 100644
> gcc/testsuite/gcc.dg/float_opposite_arm-1.c
> 
> diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc index
> 43105d20be3..299c22bf391 100644
> --- a/gcc/fold-const.cc
> +++ b/gcc/fold-const.cc
> @@ -6420,7 +6420,6 @@ static tree
>  merge_truthop_with_opposite_arm (location_t loc, tree op, tree cmpop,
>  				 bool rhs_only)
>  {
> -  tree type = TREE_TYPE (cmpop);
>    enum tree_code code = TREE_CODE (cmpop);
>    enum tree_code truthop_code = TREE_CODE (op);
>    tree lhs = TREE_OPERAND (op, 0);
> @@ -6436,6 +6435,8 @@ merge_truthop_with_opposite_arm (location_t
> loc, tree op, tree cmpop,
>    if (TREE_CODE_CLASS (code) != tcc_comparison)
>      return NULL_TREE;
> 
> +  tree type = TREE_TYPE (TREE_OPERAND (cmpop, 0));
> +
>    if (rhs_code == truthop_code)
>      {
>        tree newrhs = merge_truthop_with_opposite_arm (loc, rhs, cmpop,
> rhs_only); diff --git a/gcc/testsuite/gcc.dg/float_opposite_arm-1.c
> b/gcc/testsuite/gcc.dg/float_opposite_arm-1.c
> new file mode 100644
> index 00000000000..d2dbff35066
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/float_opposite_arm-1.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fdump-tree-original -fdump-tree-optimized" } */
> +/* { dg-add-options ieee } */
> +/* PR middle-end/95351 */
> +
> +int Foo(double possiblyNAN, double b, double c) {
> +    return (possiblyNAN <= 2.0) || ((possiblyNAN  > 2.0) && (b > c)); }
> +
> +/* Make sure we don't remove either >/<=  */
> +
> +/* { dg-final { scan-tree-dump "possiblyNAN > 2.0e.0" "original" } } */
> +/* { dg-final { scan-tree-dump "possiblyNAN_\[0-9\]+.D. > 2.0e.0"
> +"optimized" } } */
> +
> +/* { dg-final { scan-tree-dump "possiblyNAN <= 2.0e.0" "original" } }
> +*/
> +/* { dg-final { scan-tree-dump "possiblyNAN_\[0-9\]+.D. <= 2.0e.0"
> +"optimized" } } */
> --
> 2.43.0