On Mon, Jul 1, 2024 at 11:47 PM Andrew Pinski <quic_apin...@quicinc.com> wrote:
>
> This is just a small optimization for the case where the real and imag
> parts are the same when lowering complex addition/subtraction. We only
> need to do the addition once when the real and imag parts are the same (on
> both sides of the operator). This gets done later on by FRE/PRE/DOM but
> having it done soon allows the cabs lowering to remove the sqrt and
> just change it to a multiply by a constant.
>
> Bootstrapped and tested on x86_64-linux-gnu.
OK.
> gcc/ChangeLog:
>
> * tree-complex.cc (expand_complex_addition): If both
> operands have the same real and imag parts, only
> add the addition once.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/complex-8.c: New test.
>
> Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> ---
> gcc/testsuite/gcc.dg/tree-ssa/complex-8.c | 12 ++++++++++++
> gcc/tree-complex.cc | 7 ++++++-
> 2 files changed, 18 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/complex-8.c
>
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/complex-8.c
> b/gcc/testsuite/gcc.dg/tree-ssa/complex-8.c
> new file mode 100644
> index 00000000000..a9636ff9e9a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/complex-8.c
> @@ -0,0 +1,12 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fdump-tree-cplxlower1-raw" } */
> +
> +_Complex double f(double a, double c)
> +{
> + _Complex double d = __builtin_complex (a, a);
> + d+=__builtin_complex(c, c);
> + return d;
> +}
> +
> +/* There should only be one plus as (a+c) is still (a+c) */
> +/* { dg-final { scan-tree-dump-times "plus_expr, " 1 "cplxlower1" } } */
> diff --git a/gcc/tree-complex.cc b/gcc/tree-complex.cc
> index 8a879acffca..dfebec18ec3 100644
> --- a/gcc/tree-complex.cc
> +++ b/gcc/tree-complex.cc
> @@ -984,7 +984,12 @@ expand_complex_addition (gimple_stmt_iterator *gsi, tree
> inner_type,
> case PAIR (VARYING, VARYING):
> general:
> rr = gimple_build (&stmts, loc, code, inner_type, ar, br);
> - ri = gimple_build (&stmts, loc, code, inner_type, ai, bi);
> + /* (a+ai) + (b+bi) -> (a+b)+(a+b)i
> + small optimization to remove one new statement. */
> + if (operand_equal_p (ar, ai) && operand_equal_p (br, bi))
> + ri = rr;
> + else
> + ri = gimple_build (&stmts, loc, code, inner_type, ai, bi);
> break;
>
> default:
> --
> 2.43.0
>
