4 files changed, 45 insertions, 6 deletions

diff --git a/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp b/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
index cb57c43..d4d9e54 100644
--- a/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
+++ b/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
@@ -193,7 +193,7 @@ bool RISCVExpandPseudo::expandCCOp(MachineBasicBlock &MBB,
   // we need to invert the branch condition to jump over TrueBB when the
   // condition is false.
   auto CC = static_cast<RISCVCC::CondCode>(MI.getOperand(3).getImm());
-  CC = RISCVCC::getOppositeBranchCondition(CC);
+  CC = RISCVCC::getInverseBranchCondition(CC);
 
   // Insert branch instruction.
   BuildMI(MBB, MBBI, DL, TII->get(RISCVCC::getBrCond(CC)))
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index 56db09a..6d418fd 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -1134,7 +1134,7 @@ unsigned RISCVCC::getBrCond(RISCVCC::CondCode CC, unsigned SelectOpc) {
   }
 }
 
-RISCVCC::CondCode RISCVCC::getOppositeBranchCondition(RISCVCC::CondCode CC) {
+RISCVCC::CondCode RISCVCC::getInverseBranchCondition(RISCVCC::CondCode CC) {
   switch (CC) {
   default:
     llvm_unreachable("Unrecognized conditional branch");
@@ -1554,7 +1554,7 @@ bool RISCVInstrInfo::optimizeCondBranch(MachineInstr &MI) const {
     return Register();
   };
 
-  unsigned NewOpc = RISCVCC::getBrCond(getOppositeBranchCondition(CC));
+  unsigned NewOpc = RISCVCC::getBrCond(getInverseBranchCondition(CC));
 
   // Might be case 1.
   // Don't change 0 to 1 since we can use x0.
@@ -1801,7 +1801,7 @@ RISCVInstrInfo::optimizeSelect(MachineInstr &MI,
   // Add condition code, inverting if necessary.
   auto CC = static_cast<RISCVCC::CondCode>(MI.getOperand(3).getImm());
   if (Invert)
-    CC = RISCVCC::getOppositeBranchCondition(CC);
+    CC = RISCVCC::getInverseBranchCondition(CC);
   NewMI.addImm(CC);
 
   // Copy the false register.
@@ -3978,7 +3978,7 @@ MachineInstr *RISCVInstrInfo::commuteInstructionImpl(MachineInstr &MI,
   case RISCV::PseudoCCMOVGPR: {
     // CCMOV can be commuted by inverting the condition.
     auto CC = static_cast<RISCVCC::CondCode>(MI.getOperand(3).getImm());
-    CC = RISCVCC::getOppositeBranchCondition(CC);
+    CC = RISCVCC::getInverseBranchCondition(CC);
     auto &WorkingMI = cloneIfNew(MI);
     WorkingMI.getOperand(3).setImm(CC);
     return TargetInstrInfo::commuteInstructionImpl(WorkingMI, /*NewMI*/ false,
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.h b/llvm/lib/Target/RISCV/RISCVInstrInfo.h
index 2bc499b..42a0c4c 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.h
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.h
@@ -44,7 +44,7 @@ enum CondCode {
   COND_INVALID
 };
 
-CondCode getOppositeBranchCondition(CondCode);
+CondCode getInverseBranchCondition(CondCode);
 unsigned getBrCond(CondCode CC, unsigned SelectOpc = 0);
 
 } // end of namespace RISCVCC
diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index 563f3bb..d4124ae 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -167,6 +167,42 @@ static bool canUseShiftPair(Instruction *Inst, const APInt &Imm) {
   return false;
 }
 
+// If this is i64 AND is part of (X & -(1 << C1) & 0xffffffff) == C2 << C1),
+// DAGCombiner can convert this to (sraiw X, C1) == sext(C2) for RV64. On RV32,
+// the type will be split so only the lower 32 bits need to be compared using
+// (srai/srli X, C) == C2.
+static bool canUseShiftCmp(Instruction *Inst, const APInt &Imm) {
+  if (!Inst->hasOneUse())
+    return false;
+
+  // Look for equality comparison.
+  auto *Cmp = dyn_cast<ICmpInst>(*Inst->user_begin());
+  if (!Cmp || !Cmp->isEquality())
+    return false;
+
+  // Right hand side of comparison should be a constant.
+  auto *C = dyn_cast<ConstantInt>(Cmp->getOperand(1));
+  if (!C)
+    return false;
+
+  uint64_t Mask = Imm.getZExtValue();
+
+  // Mask should be of the form -(1 << C) in the lower 32 bits.
+  if (!isUInt<32>(Mask) || !isPowerOf2_32(-uint32_t(Mask)))
+    return false;
+
+  // Comparison constant should be a subset of Mask.
+  uint64_t CmpC = C->getZExtValue();
+  if ((CmpC & Mask) != CmpC)
+    return false;
+
+  // We'll need to sign extend the comparison constant and shift it right. Make
+  // sure the new constant can use addi/xori+seqz/snez.
+  unsigned ShiftBits = llvm::countr_zero(Mask);
+  int64_t NewCmpC = SignExtend64<32>(CmpC) >> ShiftBits;
+  return NewCmpC >= -2048 && NewCmpC <= 2048;
+}
+
 InstructionCost RISCVTTIImpl::getIntImmCostInst(unsigned Opcode, unsigned Idx,
                                                 const APInt &Imm, Type *Ty,
                                                 TTI::TargetCostKind CostKind,
@@ -224,6 +260,9 @@ InstructionCost RISCVTTIImpl::getIntImmCostInst(unsigned Opcode, unsigned Idx,
     if (Inst && Idx == 1 && Imm.getBitWidth() <= ST->getXLen() &&
         canUseShiftPair(Inst, Imm))
       return TTI::TCC_Free;
+    if (Inst && Idx == 1 && Imm.getBitWidth() == 64 &&
+        canUseShiftCmp(Inst, Imm))
+      return TTI::TCC_Free;
     Takes12BitImm = true;
     break;
   case Instruction::Add: