Add DAG-combines for aggressive FMA formation.

This patch adds DAG combines to form FMAs from pairs of FADD + FMUL or
FSUB + FMUL. The combines are performed when:
(a) Either
      AllowExcessFPPrecision option (-enable-excess-fp-precision for llc)
        OR
      UnsafeFPMath option (-enable-unsafe-fp-math)
    are set, and
(b) TargetLoweringInfo::isFMAFasterThanMulAndAdd(VT) is true for the type of
    the FADD/FSUB, and
(c) The FMUL only has one user (the FADD/FSUB).

If your target has fast FMA instructions you can make use of these combines by
overriding TargetLoweringInfo::isFMAFasterThanMulAndAdd(VT) to return true for
types supported by your FMA instruction, and adding patterns to match ISD::FMA
to your FMA instructions.

llvm-svn: 158757

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.td b/llvm/lib/Target/PowerPC/PPCInstrInfo.td
index c9cdd5c1920..25b6dc733ea 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.td
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.td
@@ -353,7 +353,7 @@ def xaddroff : ComplexPattern<iPTR, 1, "SelectAddrIdxOffs", [], []>;
 
 //===----------------------------------------------------------------------===//
 // PowerPC Instruction Predicate Definitions.
-def FPContractions : Predicate<"!TM.Options.NoExcessFPPrecision">;
+def FPContractions : Predicate<"TM.Options.AllowExcessFPPrecision">;
 def In32BitMode  : Predicate<"!PPCSubTarget.isPPC64()">;
 def In64BitMode  : Predicate<"PPCSubTarget.isPPC64()">;
 def IsBookE  : Predicate<"PPCSubTarget.isBookE()">;