On Mon, Oct 16, 2023 at 2:02 AM Andrew Pinski <pins...@gmail.com> wrote:
>
> In the case of a NOP conversion (precisions of the 2 types are equal),
> factoring out the conversion can be done even if int_fits_type_p returns
> false and even when the conversion is defined by a statement inside the
> conditional. Since it is a NOP conversion there is no zero/sign extending
> happening which is why it is ok to be done here.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
>
> gcc/ChangeLog:
>
> PR tree-optimization/104376
> PR tree-optimization/101541
> * tree-ssa-phiopt.cc (factor_out_conditional_operation):
> Allow nop conversions even if it is defined by a statement
> inside the conditional.
>
> gcc/testsuite/ChangeLog:
>
> PR tree-optimization/101541
> * gcc.dg/tree-ssa/phi-opt-38.c: New test.
> ---
> gcc/testsuite/gcc.dg/tree-ssa/phi-opt-38.c | 44 ++++++++++++++++++++++
> gcc/tree-ssa-phiopt.cc | 8 +++-
> 2 files changed, 50 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/phi-opt-38.c
>
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-38.c
> b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-38.c
> new file mode 100644
> index 00000000000..ca04d1619e6
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-38.c
> @@ -0,0 +1,44 @@
> +/* { dg-options "-O2 -fdump-tree-phiopt" } */
> +
> +unsigned f0(int A)
> +{
> +// A == 0? A : -A same as -A
> + if (A == 0) return A;
> + return -A;
> +}
> +
> +unsigned f1(int A)
> +{
> +// A != 0? A : -A same as A
> + if (A != 0) return A;
> + return -A;
> +}
> +unsigned f2(int A)
> +{
> +// A >= 0? A : -A same as abs (A)
> + if (A >= 0) return A;
> + return -A;
> +}
> +unsigned f3(int A)
> +{
> +// A > 0? A : -A same as abs (A)
> + if (A > 0) return A;
> + return -A;
> +}
> +unsigned f4(int A)
> +{
> +// A <= 0? A : -A same as -abs (A)
> + if (A <= 0) return A;
> + return -A;
> +}
> +unsigned f5(int A)
> +{
> +// A < 0? A : -A same as -abs (A)
> + if (A < 0) return A;
> + return -A;
> +}
> +
> +/* f4 and f5 are not allowed to be optimized in early phi-opt. */
> +/* { dg-final { scan-tree-dump-times "if" 2 "phiopt1" } } */
> +/* { dg-final { scan-tree-dump-not "if" "phiopt2" } } */
> +
> diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
> index 312a6f9082b..0ab8fad5898 100644
> --- a/gcc/tree-ssa-phiopt.cc
> +++ b/gcc/tree-ssa-phiopt.cc
> @@ -310,7 +310,9 @@ factor_out_conditional_operation (edge e0, edge e1, gphi
> *phi,
> return NULL;
> /* If arg1 is an INTEGER_CST, fold it to new type. */
> if (INTEGRAL_TYPE_P (TREE_TYPE (new_arg0))
> - && int_fits_type_p (arg1, TREE_TYPE (new_arg0)))
> + && (int_fits_type_p (arg1, TREE_TYPE (new_arg0))
> + || TYPE_PRECISION (TREE_TYPE (new_arg0))
> + == TYPE_PRECISION (TREE_TYPE (arg1))))
can you add parens for auto-indent?
> {
> if (gimple_assign_cast_p (arg0_def_stmt))
> {
> @@ -323,7 +325,9 @@ factor_out_conditional_operation (edge e0, edge e1, gphi
> *phi,
> its basic block, because then it is possible this
> could enable further optimizations (minmax replacement
> etc.). See PR71016. */
Doesn't the comment also apply for equal precision?
> - if (new_arg0 != gimple_cond_lhs (cond_stmt)
> + if (TYPE_PRECISION (TREE_TYPE (new_arg0))
> + != TYPE_PRECISION (TREE_TYPE (arg1))
> + && new_arg0 != gimple_cond_lhs (cond_stmt)
> && new_arg0 != gimple_cond_rhs (cond_stmt)
> && gimple_bb (arg0_def_stmt) == e0->src)
> {
When we later fold_convert () I think you want to drop TREE_OVERFLOW
which we eventually add.
Otherwise OK I think.
Richard.
> --
> 2.34.1
>
