Re: [PATCH] c, c++: Fix up excess precision handling of scalar_to_vector conversion [PR107358]

[Jeff Law <jeffreyalaw@gmail.com>]

On 10/24/22 01:19, Jakub Jelinek via Gcc-patches wrote:
> Hi!
>
> As mentioned earlier in the C++ excess precision support mail, the following
> testcase is broken with excess precision both in C and C++ (though just in C++
> it was triggered in real-world code).
> scalar_to_vector is called in both FEs after the excess precision promotions
> (or stripping of EXCESS_PRECISION_EXPR), so we can then get invalid
> diagnostics that say float vector + float involves truncation (on ia32
> from long double to float).
>
> The following patch fixes that by calling scalar_to_vector on the operands
> before the excess precision promotions, let scalar_to_vector just do the
> diagnostics (it does e.g. fold_for_warn so it will fold
> EXCESS_PRECISION_EXPR around REAL_CST to constants etc.) but will then
> do the actual conversions using the excess precision promoted operands
> (so say if we have vector double + (float + float) we don't actually do
> vector double + (float) ((long double) float + (long double) float)
> but
> vector double + (double) ((long double) float + (long double) float)
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2022-10-24  Jakub Jelinek  <jakub@redhat.com>
>
> 	PR c++/107358
> c/
> 	* c-typeck.cc (build_binary_op): Pass operands before excess precision
> 	promotions to scalar_to_vector call.
> cp/
> 	* typeck.cc (cp_build_binary_op): Pass operands before excess precision
> 	promotions to scalar_to_vector call.
> testsuite/
> 	* c-c++-common/pr107358.c: New test.
> 	* g++.dg/cpp1y/pr68180.C: Remove -fexcess-precision=fast from
> 	dg-options.

OK

jeff