[Driver] Make ffp-model=fast honor non-finite-values, introduce ffp-model=aggressive (#100453)

This change modifies -ffp-model=fast to select options that more closely
match -funsafe-math-optimizations, and introduces a new model,
-ffp-model=aggressive which matches the existing behavior (except for a
minor change in the fp-contract behavior).

The primary motivation for this change is to make -ffp-model=fast more
user friendly, particularly in light of LLVM's aggressive optimizations
when -fno-honor-nans and -fno-honor-infinites are used.

This was previously proposed here:

https://discourse.llvm.org/t/making-ffp-model-fast-more-user-friendly/78402

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 0e8577b..c93c971 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -1366,7 +1366,7 @@ bool ToolChain::isFastMathRuntimeAvailable(const ArgList &Args,
       Default = false;
     if (A && A->getOption().getID() == options::OPT_ffp_model_EQ) {
       StringRef Model = A->getValue();
-      if (Model != "fast")
+      if (Model != "fast" && Model != "aggressive")
         Default = false;
     }
   }