================
@@ -549,6 +562,22 @@ static bool interp__builtin_fpclassify(InterpState &S,
CodePtr OpPC,
return true;
}
+static bool interp__builtin_fma(InterpState &S, CodePtr OpPC,
+ const InterpFrame *Frame, const Function *Func,
+ const CallExpr *Call) {
+ const Floating &X = getParam<Floating>(Frame, 0);
+ const Floating &Y = getParam<Floating>(Frame, 1);
+ const Floating &Z = getParam<Floating>(Frame, 2);
+ Floating Result;
+
+ llvm::RoundingMode RM = getActiveRoundingMode(S, Call);
----------------
andykaylor wrote:
I have questions about the rounding mode. Is getActiveRoundingMode() trying to
account for the FE_ROUND pragma setting? If that pragma isn't used and we
aren't compiling in strict mode, this should give us "NearestTiesToEven", right?
But if the rounding mode is dynamic, then I think we need to know if the call
is in a constexpr. Consider:
```
float f1() {
fesetround(FE_UPWARD);
constrexpr float x = __builtin_fma(1.0f, 0.0f, 0.1f); // constexpr evaluates
at the default rounding mode?
float y = __builtin_fma(1.0f, 0.1f, 0.1f); // Non-constexpr should use the
dynamic rounding mode?
return x - y;
}
```
I'm not 100% certain about the language rules here, but at least in C my
understanding is that initialization of non-static, non-constexp expressions
should be done "as if" evaluated at runtime.
https://github.com/llvm/llvm-project/pull/113020
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