[llvm] [LoongArch][GlobalISel] Adding initial GlobalISel infrastructure (PR #76912)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,104 @@
+//===-- LoongArchInstructionSelector.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
+/// LoongArch.
+/// \todo This should be generated by TableGen.
+//===----------------------------------------------------------------------===//
+
+#include "LoongArchRegisterBankInfo.h"
+#include "LoongArchSubtarget.h"
+#include "LoongArchTargetMachine.h"
+#include "llvm/CodeGen/GlobalISel/GIMatchTableExecutorImpl.h"
+#include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
+#include "llvm/IR/IntrinsicsLoongArch.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "loongarch-isel"
+
+using namespace llvm;
+
+#define GET_GLOBALISEL_PREDICATE_BITSET
+#include "LoongArchGenGlobalISel.inc"
+#undef GET_GLOBALISEL_PREDICATE_BITSET
+
+namespace {
+
+class LoongArchInstructionSelector : public InstructionSelector {
+public:
+  LoongArchInstructionSelector(const LoongArchTargetMachine &TM,
+                               const LoongArchSubtarget &STI,
+                               const LoongArchRegisterBankInfo &RBI);
+
+  bool select(MachineInstr &I) override;
+  static const char *getName() { return DEBUG_TYPE; }
+
+private:
+  bool selectImpl(MachineInstr &I, CodeGenCoverage &CoverageInfo) const;
+
+  const LoongArchSubtarget &STI;
+  const LoongArchInstrInfo &TII;
+  const LoongArchRegisterInfo &TRI;
+  const LoongArchRegisterBankInfo &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 LoongArchSubtarget *Subtarget = &STI;
+
+#define GET_GLOBALISEL_PREDICATES_DECL
+#include "LoongArchGenGlobalISel.inc"
+#undef GET_GLOBALISEL_PREDICATES_DECL
+
+#define GET_GLOBALISEL_TEMPORARIES_DECL
+#include "LoongArchGenGlobalISel.inc"
+#undef GET_GLOBALISEL_TEMPORARIES_DECL
+};
+
+} // end anonymous namespace
+
+#define GET_GLOBALISEL_IMPL
+#include "LoongArchGenGlobalISel.inc"
+#undef GET_GLOBALISEL_IMPL
+
+LoongArchInstructionSelector::LoongArchInstructionSelector(
+    const LoongArchTargetMachine &TM, const LoongArchSubtarget &STI,
+    const LoongArchRegisterBankInfo &RBI)
+    : InstructionSelector(), STI(STI), TII(*STI.getInstrInfo()),
+      TRI(*STI.getRegisterInfo()), RBI(RBI),
+
+#define GET_GLOBALISEL_PREDICATES_INIT
+#include "LoongArchGenGlobalISel.inc"
+#undef GET_GLOBALISEL_PREDICATES_INIT
+#define GET_GLOBALISEL_TEMPORARIES_INIT
+#include "LoongArchGenGlobalISel.inc"
+#undef GET_GLOBALISEL_TEMPORARIES_INIT
+{
+}
+
+bool LoongArchInstructionSelector::select(MachineInstr &I) {
+
+  if (!isPreISelGenericOpcode(I.getOpcode())) {
+    // Certain non-generic instructions also need some special handling.
+    return true;
+  }
+
+  if (selectImpl(I, *CoverageInfo))
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arsenm wrote:

Could fold to return selectImpl but I assume this will fill in other code later 

https://github.com/llvm/llvm-project/pull/76912