[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, 17 insertions, 0 deletions

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 704b631..2df4004 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -212,6 +212,12 @@ Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
   SemaPPCallbackHandler = Callbacks.get();
   PP.addPPCallbacks(std::move(Callbacks));
   SemaPPCallbackHandler->set(*this);
+  if (getLangOpts().getFPEvalMethod() == LangOptions::FEM_TargetDefault)
+    // Use setting from TargetInfo.
+    PP.setCurrentFPEvalMethod(ctxt.getTargetInfo().getFPEvalMethod());
+  else
+    // Set initial value of __FLT_EVAL_METHOD__ from the command line.
+    PP.setCurrentFPEvalMethod(getLangOpts().getFPEvalMethod());
 }
 
 // Anchor Sema's type info to this TU.
@@ -2493,3 +2499,14 @@ const llvm::MapVector<FieldDecl *, Sema::DeleteLocs> &
 Sema::getMismatchingDeleteExpressions() const {
   return DeleteExprs;
 }
+
+Sema::FPFeaturesStateRAII::FPFeaturesStateRAII(Sema &S)
+    : S(S), OldFPFeaturesState(S.CurFPFeatures),
+      OldOverrides(S.FpPragmaStack.CurrentValue),
+      OldEvalMethod(S.PP.getCurrentFPEvalMethod()) {}
+
+Sema::FPFeaturesStateRAII::~FPFeaturesStateRAII() {
+  S.CurFPFeatures = OldFPFeaturesState;
+  S.FpPragmaStack.CurrentValue = OldOverrides;
+  S.PP.setCurrentFPEvalMethod(OldEvalMethod);
+}