1 files changed, 92 insertions, 0 deletions
diff --git a/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
new file mode 100644
index 000000000000..2c6400cbb1eb
--- /dev/null
+++ b/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -0,0 +1,92 @@
+//===-- RISCVTargetTransformInfo.cpp - RISC-V specific TTI ----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "RISCVTargetTransformInfo.h"
+#include "Utils/RISCVMatInt.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/CodeGen/BasicTTIImpl.h"
+#include "llvm/CodeGen/TargetLowering.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "riscvtti"
+
+int RISCVTTIImpl::getIntImmCost(const APInt &Imm, Type *Ty) {
+  assert(Ty->isIntegerTy() &&
+         "getIntImmCost can only estimate cost of materialising integers");
+
+  // We have a Zero register, so 0 is always free.
+  if (Imm == 0)
+    return TTI::TCC_Free;
+
+  // Otherwise, we check how many instructions it will take to materialise.
+  const DataLayout &DL = getDataLayout();
+  return RISCVMatInt::getIntMatCost(Imm, DL.getTypeSizeInBits(Ty),
+                                    getST()->is64Bit());
+}
+
+int RISCVTTIImpl::getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm,
+                                Type *Ty) {
+  assert(Ty->isIntegerTy() &&
+         "getIntImmCost can only estimate cost of materialising integers");
+
+  // We have a Zero register, so 0 is always free.
+  if (Imm == 0)
+    return TTI::TCC_Free;
+
+  // Some instructions in RISC-V can take a 12-bit immediate. Some of these are
+  // commutative, in others the immediate comes from a specific argument index.
+  bool Takes12BitImm = false;
+  unsigned ImmArgIdx = ~0U;
+
+  switch (Opcode) {
+  case Instruction::GetElementPtr:
+    // Never hoist any arguments to a GetElementPtr. CodeGenPrepare will
+    // split up large offsets in GEP into better parts than ConstantHoisting
+    // can.
+    return TTI::TCC_Free;
+  case Instruction::Add:
+  case Instruction::And:
+  case Instruction::Or:
+  case Instruction::Xor:
+  case Instruction::Mul:
+    Takes12BitImm = true;
+    break;
+  case Instruction::Sub:
+  case Instruction::Shl:
+  case Instruction::LShr:
+  case Instruction::AShr:
+    Takes12BitImm = true;
+    ImmArgIdx = 1;
+    break;
+  default:
+    break;
+  }
+
+  if (Takes12BitImm) {
+    // Check immediate is the correct argument...
+    if (Instruction::isCommutative(Opcode) || Idx == ImmArgIdx) {
+      // ... and fits into the 12-bit immediate.
+      if (Imm.getMinSignedBits() <= 64 &&
+          getTLI()->isLegalAddImmediate(Imm.getSExtValue())) {
+        return TTI::TCC_Free;
+      }
+    }
+
+    // Otherwise, use the full materialisation cost.
+    return getIntImmCost(Imm, Ty);
+  }
+
+  // By default, prevent hoisting.
+  return TTI::TCC_Free;
+}
+
+int RISCVTTIImpl::getIntImmCost(Intrinsic::ID IID, unsigned Idx,
+                                const APInt &Imm, Type *Ty) {
+  // Prevent hoisting in unknown cases.
+  return TTI::TCC_Free;
+}