[CLANG][PATCH][FPEnv] Add support for option -ffp-eval-method and extend #pragma float_control similarly

The Intel compiler ICC supports the option "-fp-model=(source|double|extended)"
which causes the compiler to use a wider type for intermediate floating point
calculations. Also supported is a way to embed this effect in the source
program with #pragma float_control(source|double|extended).
This patch extends pragma float_control syntax, and also adds support
for a new floating point option "-ffp-eval-method=(source|double|extended)".
source: intermediate results use source precision
double: intermediate results use double precision
extended: intermediate results use extended precision

Reviewed By: Aaron Ballman

Differential Revision: https://reviews.llvm.org/D93769

1 files changed, 6 insertions, 1 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 2c696b5..4c266f5 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -4239,8 +4239,13 @@ static bool ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
   // Always avoid lexing editor placeholders when we're just running the
   // preprocessor as we never want to emit the
   // "editor placeholder in source file" error in PP only mode.
-  if (isStrictlyPreprocessorAction(Action))
+  // Certain predefined macros which depend upon semantic processing,
+  // for example __FLT_EVAL_METHOD__, are not expanded in PP mode, they
+  // appear in the preprocessed output as an unexpanded macro name.
+  if (isStrictlyPreprocessorAction(Action)) {
     Opts.LexEditorPlaceholders = false;
+    Opts.LexExpandSpecialBuiltins = false;
+  }
 
   return Diags.getNumErrors() == NumErrorsBefore;
 }