Add a target hook for FLT_EVAL_METHOD and use it to set the value on x86 with sse disabled.

x87 math evaluates everything with 80 bits precision, so we have to set FLT_EVAL_METHOD
to "2".

llvm-svn: 147311

2 files changed, 5 insertions, 1 deletions

diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
index 34258c10546..bb1051d7403 100644
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -1339,6 +1339,10 @@ public:
     BigEndian = false;
     LongDoubleFormat = &llvm::APFloat::x87DoubleExtended;
   }
+  virtual unsigned getFloatEvalMethod() const {
+    // X87 evaluates with 80 bits "long double" precision.
+    return SSELevel == NoSSE ? 2 : 0;
+  }
   virtual void getTargetBuiltins(const Builtin::Info *&Records,
                                  unsigned &NumRecords) const {
     Records = BuiltinInfo;
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index c67eba40b59..f601f3d73ab 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -513,7 +513,7 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   }
 
   // Macros to control C99 numerics and <float.h>
-  Builder.defineMacro("__FLT_EVAL_METHOD__", "0");
+  Builder.defineMacro("__FLT_EVAL_METHOD__", Twine(TI.getFloatEvalMethod()));
   Builder.defineMacro("__FLT_RADIX__", "2");
   int Dig = PickFP(&TI.getLongDoubleFormat(), -1/*FIXME*/, 17, 21, 33, 36);
   Builder.defineMacro("__DECIMAL_DIG__", Twine(Dig));