Don't create ISD::FNEG nodes after legalize if they aren't legal.
Simplify x+0 to x in unsafe-fp-math mode. This avoids a bunch of
redundant work in many cases, because in unsafe-fp-math mode,
ISD::FADD with a constant is considered free to negate, so the
DAGCombiner often negates x+0 to -0-x thinking it's free, when
in reality the end result is -x, which is more expensive than x.
Also, combine x*0 to 0.
This fixes PR3374.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62789 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index a088560..2974486 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -27,6 +27,7 @@
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/CommandLine.h"
@@ -2391,16 +2392,26 @@
case ISD::UREM:
case ISD::MULHU:
case ISD::MULHS:
- assert(VT.isInteger() && "This operator does not apply to FP types!");
- // fall through
case ISD::MUL:
case ISD::SDIV:
case ISD::SREM:
+ assert(VT.isInteger() && "This operator does not apply to FP types!");
+ // fall through
case ISD::FADD:
case ISD::FSUB:
case ISD::FMUL:
case ISD::FDIV:
case ISD::FREM:
+ if (UnsafeFPMath && Opcode == ISD::FADD) {
+ // 0+x --> x
+ if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(N1))
+ if (CFP->getValueAPF().isZero())
+ return N2;
+ // x+0 --> x
+ if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(N2))
+ if (CFP->getValueAPF().isZero())
+ return N1;
+ }
assert(N1.getValueType() == N2.getValueType() &&
N1.getValueType() == VT && "Binary operator types must match!");
break;