Reapply "Add support for #pragma float_control" with buildbot fixes

Add support for #pragma float_control

Reviewers: rjmccall, erichkeane, sepavloff

Differential Revision: https://reviews.llvm.org/D72841

This reverts commit fce82c0ed310174fe48e2402ac731b6340098389.

1 files changed, 9 insertions, 12 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index 24e01c4..4fcf31a 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -117,8 +117,8 @@ CodeGenFunction::~CodeGenFunction() {
 
 // Map the LangOption for exception behavior into
 // the corresponding enum in the IR.
-static llvm::fp::ExceptionBehavior ToConstrainedExceptMD(
-  LangOptions::FPExceptionModeKind Kind) {
+llvm::fp::ExceptionBehavior
+clang::ToConstrainedExceptMD(LangOptions::FPExceptionModeKind Kind) {
 
   switch (Kind) {
   case LangOptions::FPE_Ignore:  return llvm::fp::ebIgnore;
@@ -133,15 +133,10 @@ void CodeGenFunction::SetFPModel() {
   auto fpExceptionBehavior = ToConstrainedExceptMD(
                                getLangOpts().getFPExceptionMode());
 
-  if (fpExceptionBehavior == llvm::fp::ebIgnore &&
-      RM == llvm::RoundingMode::NearestTiesToEven)
-    // Constrained intrinsics are not used.
-    ;
-  else {
-    Builder.setIsFPConstrained(true);
-    Builder.setDefaultConstrainedRounding(RM);
-    Builder.setDefaultConstrainedExcept(fpExceptionBehavior);
-  }
+  Builder.setDefaultConstrainedRounding(RM);
+  Builder.setDefaultConstrainedExcept(fpExceptionBehavior);
+  Builder.setIsFPConstrained(fpExceptionBehavior != llvm::fp::ebIgnore ||
+                             RM != llvm::RoundingMode::NearestTiesToEven);
 }
 
 CharUnits CodeGenFunction::getNaturalPointeeTypeAlignment(QualType T,
@@ -919,9 +914,11 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
       Fn->addFnAttr(llvm::Attribute::NoRecurse);
   }
 
-  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
+  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
+    Builder.setIsFPConstrained(FD->usesFPIntrin());
     if (FD->usesFPIntrin())
       Fn->addFnAttr(llvm::Attribute::StrictFP);
+  }
 
   // If a custom alignment is used, force realigning to this alignment on
   // any main function which certainly will need it.