From 10def396cba31bc2358a92bc5d714fceb17cbbd3 Mon Sep 17 00:00:00 2001 From: Michael Ilseman Date: Mon, 10 Sep 2012 17:00:37 +0000 Subject: [PATCH] Fold multiply by 0 or 1 when in UnsafeFPMath mode in SelectionDAG::getNode(). This folding happens as early as possible for performance reasons, and to make sure it isn't foiled by other transforms (e.g. forming FMAs). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163519 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index c6f49c8ddcb..d85d41bd86a 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -2816,6 +2816,24 @@ SDValue SelectionDAG::getNode(unsigned Opcode, DebugLoc DL, EVT VT, if (ConstantFPSDNode *CFP = dyn_cast(N2)) if (CFP->getValueAPF().isZero()) return N1; + } else if (Opcode == ISD::FMUL) { + ConstantFPSDNode *CFP = dyn_cast(N1); + SDValue V = N2; + + // If the first operand isn't the constant, try the second + if (!CFP) { + CFP = dyn_cast(N2); + V = N1; + } + + if (CFP) { + // 0*x --> 0 + if (CFP->isZero()) + return SDValue(CFP,0); + // 1*x --> x + if (CFP->isExactlyValue(1.0)) + return V; + } } } assert(VT.isFloatingPoint() && "This operator only applies to FP types!"); -- 2.11.0