[RISCV GlobalISel] Adding initial GlobalISel infrastructure

Summary:
Add an initial GlobalISel skeleton for RISCV. It can only run ir translator for `ret void`.

Patch by Andrew Wei

Reviewers: asb, sabuasal, apazos, lenary, simoncook, lewis-revill, edward-jones, rogfer01, xiangzhai, rovka, Petar.Avramovic, mgorny, dsanders

Reviewed By: dsanders

Subscribers: pzheng, s.egerton, dsanders, hiraditya, rbar, johnrusso, niosHD, kito-cheng, shiva0217, jrtc27, MaskRay, zzheng, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, psnobl, benna, Jim, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65219

llvm-svn: 369467

1 files changed, 103 insertions, 0 deletions

diff --git a/llvm/lib/Target/RISCV/RISCVInstructionSelector.cpp b/llvm/lib/Target/RISCV/RISCVInstructionSelector.cpp
new file mode 100644
index 00000000000..5bd09a54611
--- /dev/null
+++ b/llvm/lib/Target/RISCV/RISCVInstructionSelector.cpp
@@ -0,0 +1,103 @@
+//===-- RISCVInstructionSelector.cpp -----------------------------*- C++ -*-==//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This file implements the targeting of the InstructionSelector class for
+/// RISCV.
+/// \todo This should be generated by TableGen.
+//===----------------------------------------------------------------------===//
+
+#include "RISCVRegisterBankInfo.h"
+#include "RISCVSubtarget.h"
+#include "RISCVTargetMachine.h"
+#include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
+#include "llvm/CodeGen/GlobalISel/InstructionSelectorImpl.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "riscv-isel"
+
+using namespace llvm;
+
+#define GET_GLOBALISEL_PREDICATE_BITSET
+#include "RISCVGenGlobalISel.inc"
+#undef GET_GLOBALISEL_PREDICATE_BITSET
+
+namespace {
+
+class RISCVInstructionSelector : public InstructionSelector {
+public:
+  RISCVInstructionSelector(const RISCVTargetMachine &TM,
+                           const RISCVSubtarget &STI,
+                           const RISCVRegisterBankInfo &RBI);
+
+  bool select(MachineInstr &I) override;
+  static const char *getName() { return DEBUG_TYPE; }
+
+private:
+  bool selectImpl(MachineInstr &I, CodeGenCoverage &CoverageInfo) const;
+
+  const RISCVSubtarget &STI;
+  const RISCVInstrInfo &TII;
+  const RISCVRegisterInfo &TRI;
+  const RISCVRegisterBankInfo &RBI;
+
+  // FIXME: This is necessary because DAGISel uses "Subtarget->" and GlobalISel
+  // uses "STI." in the code generated by TableGen. We need to unify the name of
+  // Subtarget variable.
+  const RISCVSubtarget *Subtarget = &STI;
+
+#define GET_GLOBALISEL_PREDICATES_DECL
+#include "RISCVGenGlobalISel.inc"
+#undef GET_GLOBALISEL_PREDICATES_DECL
+
+#define GET_GLOBALISEL_TEMPORARIES_DECL
+#include "RISCVGenGlobalISel.inc"
+#undef GET_GLOBALISEL_TEMPORARIES_DECL
+};
+
+} // end anonymous namespace
+
+#define GET_GLOBALISEL_IMPL
+#include "RISCVGenGlobalISel.inc"
+#undef GET_GLOBALISEL_IMPL
+
+RISCVInstructionSelector::RISCVInstructionSelector(
+    const RISCVTargetMachine &TM, const RISCVSubtarget &STI,
+    const RISCVRegisterBankInfo &RBI)
+    : InstructionSelector(), STI(STI), TII(*STI.getInstrInfo()),
+      TRI(*STI.getRegisterInfo()), RBI(RBI),
+
+#define GET_GLOBALISEL_PREDICATES_INIT
+#include "RISCVGenGlobalISel.inc"
+#undef GET_GLOBALISEL_PREDICATES_INIT
+#define GET_GLOBALISEL_TEMPORARIES_INIT
+#include "RISCVGenGlobalISel.inc"
+#undef GET_GLOBALISEL_TEMPORARIES_INIT
+{
+}
+
+bool RISCVInstructionSelector::select(MachineInstr &I) {
+
+  if (!isPreISelGenericOpcode(I.getOpcode())) {
+    // Certain non-generic instructions also need some special handling.
+    return true;
+  }
+
+  if (selectImpl(I, *CoverageInfo))
+    return true;
+
+  return false;
+}
+
+namespace llvm {
+InstructionSelector *
+createRISCVInstructionSelector(const RISCVTargetMachine &TM,
+                               RISCVSubtarget &Subtarget,
+                               RISCVRegisterBankInfo &RBI) {
+  return new RISCVInstructionSelector(TM, Subtarget, RBI);
+}
+} // end namespace llvm