On Tue, Aug 3, 2021 at 3:34 AM Joseph Myers <jos...@codesourcery.com> wrote:
>
> On Mon, 2 Aug 2021, liuhongt via Gcc-patches wrote:
>
> > diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> > index 7979e240426..dc673c89bc8 100644
> > --- a/gcc/config/i386/i386.c
> > +++ b/gcc/config/i386/i386.c
> > @@ -23352,6 +23352,8 @@ ix86_get_excess_precision (enum
> > excess_precision_type type)
> > return (type == EXCESS_PRECISION_TYPE_STANDARD
> > ? FLT_EVAL_METHOD_PROMOTE_TO_FLOAT
> > : FLT_EVAL_METHOD_UNPREDICTABLE);
> > + case EXCESS_PRECISION_TYPE_FLOAT16:
> > + return FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16;
> > default:
> > gcc_unreachable ();
> > }
>
> I'd expect an error for -fexcess-precision=16 with -mfpmath=387 (since x87
> doesn't do float or double arithmetic, but -fexcess-precision=16 implies
> that all of _Float16, float and double are represented to the range and
> precision of their type withou any excess precision).
>
Yes, additional changes like this.
modified gcc/config/i386/i386.c
@@ -23443,6 +23443,9 @@ ix86_get_excess_precision (enum
excess_precision_type type)
? FLT_EVAL_METHOD_PROMOTE_TO_FLOAT
: FLT_EVAL_METHOD_UNPREDICTABLE);
case EXCESS_PRECISION_TYPE_FLOAT16:
+ if (TARGET_80387
+ && !(TARGET_SSE_MATH && TARGET_SSE))
+ error ("%<-fexcess-precision=16%> is not compatible with %<-mfpmath=387%>");
return FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16;
default:
gcc_unreachable ();
new file gcc/testsuite/gcc.target/i386/float16-7.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mfpmath=387 -fexcess-precision=16" } */
+/* { dg-excess-errors "'-fexcess-precision=16' is not compatible with
'-mfpmath=387'" } */
+_Float16
+foo (_Float16 a, _Float16 b)
+{
+ return a + b;/* { dg-error "'-fexcess-precision=16' is not
compatible with '-mfpmath=387'" } */
+}
+
> --
> Joseph S. Myers
> jos...@codesourcery.com
--
BR,
Hongtao
