Add a new intrinsic: llvm.fmuladd. This intrinsic represents a multiply-add

expression (a * b + c) that can be implemented as a fused multiply-add (fma)
if the target determines that this will be more efficient. This intrinsic
will be used to implement FP_CONTRACT support and an aggressive FMA formation
mode.

If your target has a fast FMA instruction you should override the
isFMAFasterThanMulAndAdd method in TargetLowering to return true.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158014 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Intrinsics.td

@@ -266,6 +266,10 @@ let Properties = [IntrNoMem] in {
   def int_fma  : Intrinsic<[llvm_anyfloat_ty],
                          [LLVMMatchType<0>, LLVMMatchType<0>,
                           LLVMMatchType<0>]>;
+
+  def int_fmuladd : Intrinsic<[llvm_anyfloat_ty],
+                              [LLVMMatchType<0>, LLVMMatchType<0>,
+                               LLVMMatchType<0>]>;
 }
 
 // NOTE: these are internal interfaces.

include/llvm/Target/TargetLowering.h

@@ -1657,6 +1657,14 @@ public:
     return false;
   }
 
+  /// isFMAFasterThanMulAndAdd - Return true if an FMA operation is faster than
+  /// a pair of mul and add instructions. fmuladd intrinsics will be expanded to
+  /// FMAs when this method returns true (and FMAs are legal), otherwise fmuladd
+  /// is expanded to mul + add.
+  virtual bool isFMAFasterThanMulAndAdd(EVT) const {
+    return false;
+  }
+
   /// isNarrowingProfitable - Return true if it's profitable to narrow
   /// operations of type VT1 to VT2. e.g. on x86, it's profitable to narrow
   /// from i32 to i8 but not from i32 to i16.