[SDAG] Add AllowContract to SNodeFlags

Properly propagate the FMF from the LLVM IR to this flag.

This is toward moving fp-contraction=fast from an LLVM TargetOption to a
FastMathFlag in order to fix PR25721.

Differential Revision: https://reviews.llvm.org/D31165

llvm-svn: 298961

llvm/include/llvm/CodeGen/SelectionDAGNodes.h

@@ -350,13 +350,15 @@ struct SDNodeFlags {
   bool NoSignedZeros : 1;
   bool AllowReciprocal : 1;
   bool VectorReduction : 1;
+  bool AllowContract : 1;
 
 public:
   /// Default constructor turns off all optimization flags.
   SDNodeFlags()
       : NoUnsignedWrap(false), NoSignedWrap(false), Exact(false),
         UnsafeAlgebra(false), NoNaNs(false), NoInfs(false),
-        NoSignedZeros(false), AllowReciprocal(false), VectorReduction(false) {}
+        NoSignedZeros(false), AllowReciprocal(false), VectorReduction(false),
+        AllowContract(false) {}
 
   // These are mutators for each flag.
   void setNoUnsignedWrap(bool b) { NoUnsignedWrap = b; }
@@ -368,6 +370,7 @@ struct SDNodeFlags {
   void setNoSignedZeros(bool b) { NoSignedZeros = b; }
   void setAllowReciprocal(bool b) { AllowReciprocal = b; }
   void setVectorReduction(bool b) { VectorReduction = b; }
+  void setAllowContract(bool b) { AllowContract = b; }
 
   // These are accessors for each flag.
   bool hasNoUnsignedWrap() const { return NoUnsignedWrap; }
@@ -379,6 +382,7 @@ struct SDNodeFlags {
   bool hasNoSignedZeros() const { return NoSignedZeros; }
   bool hasAllowReciprocal() const { return AllowReciprocal; }
   bool hasVectorReduction() const { return VectorReduction; }
+  bool hasAllowContract() const { return AllowContract; }
 
   /// Clear any flags in this flag set that aren't also set in Flags.
   void intersectWith(const SDNodeFlags *Flags) {
@@ -390,6 +394,7 @@ struct SDNodeFlags {
     NoInfs &= Flags->NoInfs;
     NoSignedZeros &= Flags->NoSignedZeros;
     AllowReciprocal &= Flags->AllowReciprocal;
+    AllowContract &= Flags->AllowContract;
   }
 };
 

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

@@ -2588,6 +2588,7 @@ void SelectionDAGBuilder::visitBinary(const User &I, unsigned OpCode) {
   Flags.setVectorReduction(vec_redux);
   if (EnableFMFInDAG) {
     Flags.setAllowReciprocal(FMF.allowReciprocal());
+    Flags.setAllowContract(FMF.allowContract());
     Flags.setNoInfs(FMF.noInfs());
     Flags.setNoNaNs(FMF.noNaNs());
     Flags.setNoSignedZeros(FMF.noSignedZeros());