Initial checkin of the new "fast" instruction selection support. See

the comments in FastISelEmitter.cpp for details on what this is.
This is currently experimental and unusable.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54751 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 104 insertions, 0 deletions

diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
new file mode 100644
index 0000000000..6fe941fecb
--- /dev/null
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -0,0 +1,104 @@
+///===-- FastISel.cpp - Implementation of the FastISel class --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the implementation of the FastISel class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/FastISel.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Target/TargetInstrInfo.h"
+using namespace llvm;
+
+BasicBlock::iterator
+FastISel::SelectInstructions(BasicBlock::iterator Begin, BasicBlock::iterator End,
+                             DenseMap<const Value*, unsigned> &ValueMap) {
+  BasicBlock::iterator I = Begin;
+
+  for (; I != End; ++I) {
+    switch (I->getOpcode()) {
+    case Instruction::Add: {
+      unsigned Op0 = ValueMap[I->getOperand(0)];
+      unsigned Op1 = ValueMap[I->getOperand(1)];
+      MVT VT = MVT::getMVT(I->getType(), /*HandleUnknown=*/true);
+      if (VT == MVT::Other || !VT.isSimple()) {
+        // Unhandled type. Halt "fast" selection and bail.
+        return I;
+      }
+      unsigned ResultReg = FastEmit_rr(VT.getSimpleVT(), ISD::ADD, Op0, Op1);
+      ValueMap[I] = ResultReg;
+      break;
+    }
+    default:
+      // Unhandled instruction. Halt "fast" selection and bail.
+      return I;
+    }
+  }
+
+  return I;
+}
+
+unsigned FastISel::FastEmit_(MVT::SimpleValueType, ISD::NodeType) {
+  return 0;
+}
+
+unsigned FastISel::FastEmit_r(MVT::SimpleValueType, ISD::NodeType,
+                              unsigned /*Op0*/) {
+  return 0;
+}
+
+unsigned FastISel::FastEmit_rr(MVT::SimpleValueType, ISD::NodeType,
+                               unsigned /*Op0*/, unsigned /*Op0*/) {
+  return 0;
+}
+
+unsigned FastISel::FastEmitInst_(unsigned MachineInstOpcode,
+                                    const TargetRegisterClass* RC) {
+  MachineRegisterInfo &MRI = MF->getRegInfo();
+  const TargetInstrDesc &II = TII->get(MachineInstOpcode);
+  MachineInstr *MI = BuildMI(*MF, II);
+  unsigned ResultReg = MRI.createVirtualRegister(RC);
+
+  MI->addOperand(MachineOperand::CreateReg(ResultReg, true));
+
+  MBB->push_back(MI);
+  return ResultReg;
+}
+
+unsigned FastISel::FastEmitInst_r(unsigned MachineInstOpcode,
+                                  const TargetRegisterClass *RC,
+                                  unsigned Op0) {
+  MachineRegisterInfo &MRI = MF->getRegInfo();
+  const TargetInstrDesc &II = TII->get(MachineInstOpcode);
+  MachineInstr *MI = BuildMI(*MF, II);
+  unsigned ResultReg = MRI.createVirtualRegister(RC);
+
+  MI->addOperand(MachineOperand::CreateReg(ResultReg, true));
+  MI->addOperand(MachineOperand::CreateReg(Op0, false));
+
+  MBB->push_back(MI);
+  return ResultReg;
+}
+
+unsigned FastISel::FastEmitInst_rr(unsigned MachineInstOpcode,
+                                   const TargetRegisterClass *RC,
+                                   unsigned Op0, unsigned Op1) {
+  MachineRegisterInfo &MRI = MF->getRegInfo();
+  const TargetInstrDesc &II = TII->get(MachineInstOpcode);
+  MachineInstr *MI = BuildMI(*MF, II);
+  unsigned ResultReg = MRI.createVirtualRegister(RC);
+
+  MI->addOperand(MachineOperand::CreateReg(ResultReg, true));
+  MI->addOperand(MachineOperand::CreateReg(Op0, false));
+  MI->addOperand(MachineOperand::CreateReg(Op1, false));
+
+  MBB->push_back(MI);
+  return ResultReg;
+}