================
@@ -13861,6 +13897,36 @@ Sema::CheckReturnValExpr(Expr *RetValExp, QualType
lhsType,
CheckPPCMMAType(RetValExp->getType(), ReturnLoc);
}
+/// Diagnose comparison to NAN or INFINITY in fast math modes.
+/// The comparison to NaN or INFINITY is always false in
+/// fast modes: float evaluation will not result in inf or nan.
+void Sema::CheckInfNaNFloatComparison(SourceLocation Loc, Expr *LHS, Expr *RHS,
----------------
AaronBallman wrote:
The basic idea I have is that it's UB to generate a constant infinity or NaN if
infinity/NaN is disabled. Instead of performing special logic for float
comparisons, I think the logic should live in `Sema::ActOnNumericConstant()` so
that we capture any time a float or infinity constant is used. e.g. `inf + 1`
should also diagnose.
Then the tautological comparison component to this could be implemented by
looking for calls to `__builtin_isinf` or `__builtin_isnan` and claim those are
tautologically false (as a follow-up patch). WDYT?
https://github.com/llvm/llvm-project/pull/76873
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