[Bug target/82626] -msse and -mfpmath=sse Causes __FLT_EVAL_METHOD__ to be -1

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82626

--- Comment #13 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
Strictly, all x86 excess precision cases are indeterminable (semantics of 
-1) except for the case where -fexcess-precision=standard is used 
(requires front-end support, present for C only), because of the 
possibility of intermediate values getting narrowed when spilt to the 
stack; in the absence of -fexcess-precision=standard, the choice of 
FLT_EVAL_METHOD is a heuristic one based on what code is likely to expect 
values of that macro to mean (including based on 
-fpermitted-flt-eval-methods= to control whether TS 18661-3 values can be 
used).  Given the obscurity of the -msse -mno-sse2 -mfpmath=sse case I 
don't really think it makes sense to add a new enum flt_eval_method value 
and associated code that would be required to make that case of excess 
precision supported and predictable with -fexcess-precision=standard.