[AMDGPU] Simplify setcc (sext from i1 b), -1|0, cc
Depending on the compare code that can be either an argument of
sext or negate of it. This helps to avoid v_cndmask_b64 instruction
for sext. A reversed value can be further simplified and folded into
its parent comparison if possible.
Differential Revision: https://reviews.llvm.org/D34545
llvm-svn: 306446
diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index 8ba69c7..d39b345 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -5135,6 +5135,35 @@
SDValue LHS = N->getOperand(0);
SDValue RHS = N->getOperand(1);
EVT VT = LHS.getValueType();
+ ISD::CondCode CC = cast<CondCodeSDNode>(N->getOperand(2))->get();
+
+ auto CRHS = dyn_cast<ConstantSDNode>(RHS);
+ if (!CRHS) {
+ CRHS = dyn_cast<ConstantSDNode>(LHS);
+ if (CRHS) {
+ std::swap(LHS, RHS);
+ CC = getSetCCSwappedOperands(CC);
+ }
+ }
+
+ if (CRHS && VT == MVT::i32 && LHS.getOpcode() == ISD::SIGN_EXTEND &&
+ isBoolSGPR(LHS.getOperand(0))) {
+ // setcc (sext from i1 cc), -1, ne|sgt|ult) => not cc => xor cc, -1
+ // setcc (sext from i1 cc), -1, eq|sle|uge) => cc
+ // setcc (sext from i1 cc), 0, eq|sge|ule) => not cc => xor cc, -1
+ // setcc (sext from i1 cc), 0, ne|ugt|slt) => cc
+ if ((CRHS->isAllOnesValue() &&
+ (CC == ISD::SETNE || CC == ISD::SETGT || CC == ISD::SETULT)) ||
+ (CRHS->isNullValue() &&
+ (CC == ISD::SETEQ || CC == ISD::SETGE || CC == ISD::SETULE)))
+ return DAG.getNode(ISD::XOR, SL, MVT::i1, LHS.getOperand(0),
+ DAG.getConstant(-1, SL, MVT::i1));
+ if ((CRHS->isAllOnesValue() &&
+ (CC == ISD::SETEQ || CC == ISD::SETLE || CC == ISD::SETUGE)) ||
+ (CRHS->isNullValue() &&
+ (CC == ISD::SETNE || CC == ISD::SETUGT || CC == ISD::SETLT)))
+ return LHS.getOperand(0);
+ }
if (VT != MVT::f32 && VT != MVT::f64 && (Subtarget->has16BitInsts() &&
VT != MVT::f16))
@@ -5142,7 +5171,6 @@
// Match isinf pattern
// (fcmp oeq (fabs x), inf) -> (fp_class x, (p_infinity | n_infinity))
- ISD::CondCode CC = cast<CondCodeSDNode>(N->getOperand(2))->get();
if (CC == ISD::SETOEQ && LHS.getOpcode() == ISD::FABS) {
const ConstantFPSDNode *CRHS = dyn_cast<ConstantFPSDNode>(RHS);
if (!CRHS)