[llvm] r357029 - [SDAG] add simplifications for FP at node creation time
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Tue Mar 26 13:54:15 PDT 2019
Author: spatel
Date: Tue Mar 26 13:54:15 2019
New Revision: 357029
URL: http://llvm.org/viewvc/llvm-project?rev=357029&view=rev
Log:
[SDAG] add simplifications for FP at node creation time
We have the folds for fadd/fsub/fmul already in DAGCombiner,
so it may be possible to remove that code if we can guarantee that
these ops are zapped before they can exist.
Modified:
llvm/trunk/include/llvm/CodeGen/SelectionDAG.h
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
llvm/trunk/test/CodeGen/X86/extract-fp.ll
Modified: llvm/trunk/include/llvm/CodeGen/SelectionDAG.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/SelectionDAG.h?rev=357029&r1=357028&r2=357029&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/SelectionDAG.h (original)
+++ llvm/trunk/include/llvm/CodeGen/SelectionDAG.h Tue Mar 26 13:54:15 2019
@@ -976,6 +976,10 @@ public:
/// Try to simplify a shift into 1 of its operands or a constant.
SDValue simplifyShift(SDValue X, SDValue Y);
+ /// Try to simplify a floating-point binary operation into 1 of its operands
+ /// or a constant.
+ SDValue simplifyFPBinop(unsigned Opcode, SDValue X, SDValue Y);
+
/// VAArg produces a result and token chain, and takes a pointer
/// and a source value as input.
SDValue getVAArg(EVT VT, const SDLoc &dl, SDValue Chain, SDValue Ptr,
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp?rev=357029&r1=357028&r2=357029&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Tue Mar 26 13:54:15 2019
@@ -4931,6 +4931,8 @@ SDValue SelectionDAG::getNode(unsigned O
assert(VT.isFloatingPoint() && "This operator only applies to FP types!");
assert(N1.getValueType() == N2.getValueType() &&
N1.getValueType() == VT && "Binary operator types must match!");
+ if (SDValue V = simplifyFPBinop(Opcode, N1, N2))
+ return V;
break;
case ISD::FCOPYSIGN: // N1 and result must match. N1/N2 need not match.
assert(N1.getValueType() == VT &&
@@ -7052,6 +7054,31 @@ SDValue SelectionDAG::simplifyShift(SDVa
return SDValue();
}
+
+// TODO: Use fast-math-flags to enable more simplifications.
+SDValue SelectionDAG::simplifyFPBinop(unsigned Opcode, SDValue X, SDValue Y) {
+ ConstantFPSDNode *YC = isConstOrConstSplatFP(Y, /* AllowUndefs */ true);
+ if (!YC)
+ return SDValue();
+
+ // X + -0.0 --> X
+ if (Opcode == ISD::FADD)
+ if (YC->getValueAPF().isNegZero())
+ return X;
+
+ // X - +0.0 --> X
+ if (Opcode == ISD::FSUB)
+ if (YC->getValueAPF().isPosZero())
+ return X;
+
+ // X * 1.0 --> X
+ // X / 1.0 --> X
+ if (Opcode == ISD::FMUL || Opcode == ISD::FDIV)
+ if (YC->getValueAPF().isExactlyValue(1.0))
+ return X;
+
+ return SDValue();
+}
SDValue SelectionDAG::getVAArg(EVT VT, const SDLoc &dl, SDValue Chain,
SDValue Ptr, SDValue SV, unsigned Align) {
Modified: llvm/trunk/test/CodeGen/X86/extract-fp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/extract-fp.ll?rev=357029&r1=357028&r2=357029&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/extract-fp.ll (original)
+++ llvm/trunk/test/CodeGen/X86/extract-fp.ll Tue Mar 26 13:54:15 2019
@@ -36,12 +36,11 @@ define float @ext_fmul_v4f32(<4 x float>
ret float %ext
}
-; TODO: X / 1.0 --> X
+; X / 1.0 --> X
define float @ext_fdiv_v4f32(<4 x float> %x) {
; CHECK-LABEL: ext_fdiv_v4f32:
; CHECK: # %bb.0:
-; CHECK-NEXT: divss {{.*}}(%rip), %xmm0
; CHECK-NEXT: retq
%bo = fdiv <4 x float> %x, <float 1.0, float 2.0, float 3.0, float 42.0>
%ext = extractelement <4 x float> %bo, i32 0
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