1 files changed, 111 insertions, 0 deletions
diff --git a/include/llvm/CodeGen/GlobalISel/GISelKnownBits.h b/include/llvm/CodeGen/GlobalISel/GISelKnownBits.h
new file mode 100644
index 000000000000..dfe5a7f3177d
--- /dev/null
+++ b/include/llvm/CodeGen/GlobalISel/GISelKnownBits.h
@@ -0,0 +1,111 @@
+//===- llvm/CodeGen/GlobalISel/GISelKnownBits.h ---------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+/// Provides analysis for querying information about KnownBits during GISel
+/// passes.
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_CODEGEN_GLOBALISEL_KNOWNBITSINFO_H
+#define LLVM_CODEGEN_GLOBALISEL_KNOWNBITSINFO_H
+
+#include "llvm/CodeGen/GlobalISel/GISelChangeObserver.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/Register.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/KnownBits.h"
+
+namespace llvm {
+
+class TargetLowering;
+class DataLayout;
+
+class GISelKnownBits : public GISelChangeObserver {
+  MachineFunction &MF;
+  MachineRegisterInfo &MRI;
+  const TargetLowering &TL;
+  const DataLayout &DL;
+
+public:
+  GISelKnownBits(MachineFunction &MF);
+  virtual ~GISelKnownBits() = default;
+  void setMF(MachineFunction &MF);
+  virtual void computeKnownBitsImpl(Register R, KnownBits &Known,
+                                    const APInt &DemandedElts,
+                                    unsigned Depth = 0);
+
+  // KnownBitsAPI
+  KnownBits getKnownBits(Register R);
+  // Calls getKnownBits for first operand def of MI.
+  KnownBits getKnownBits(MachineInstr &MI);
+  APInt getKnownZeroes(Register R);
+  APInt getKnownOnes(Register R);
+
+  /// \return true if 'V & Mask' is known to be zero in DemandedElts. We use
+  /// this predicate to simplify operations downstream.
+  /// Mask is known to be zero for bits that V cannot have.
+  bool maskedValueIsZero(Register Val, const APInt &Mask) {
+    return Mask.isSubsetOf(getKnownBits(Val).Zero);
+  }
+
+  /// \return true if the sign bit of Op is known to be zero.  We use this
+  /// predicate to simplify operations downstream.
+  bool signBitIsZero(Register Op);
+
+  // FIXME: Is this the right place for G_FRAME_INDEX? Should it be in
+  // TargetLowering?
+  void computeKnownBitsForFrameIndex(Register R, KnownBits &Known,
+                                     const APInt &DemandedElts,
+                                     unsigned Depth = 0);
+  static Align inferAlignmentForFrameIdx(int FrameIdx, int Offset,
+                                         const MachineFunction &MF);
+  static void computeKnownBitsForAlignment(KnownBits &Known,
+                                           MaybeAlign Alignment);
+
+  // Try to infer alignment for MI.
+  static MaybeAlign inferPtrAlignment(const MachineInstr &MI);
+
+  // Observer API. No-op for non-caching implementation.
+  void erasingInstr(MachineInstr &MI) override{};
+  void createdInstr(MachineInstr &MI) override{};
+  void changingInstr(MachineInstr &MI) override{};
+  void changedInstr(MachineInstr &MI) override{};
+
+protected:
+  unsigned getMaxDepth() const { return 6; }
+};
+
+/// To use KnownBitsInfo analysis in a pass,
+/// KnownBitsInfo &Info = getAnalysis<GISelKnownBitsInfoAnalysis>().get(MF);
+/// Add to observer if the Info is caching.
+/// WrapperObserver.addObserver(Info);
+
+/// Eventually add other features such as caching/ser/deserializing
+/// to MIR etc. Those implementations can derive from GISelKnownBits
+/// and override computeKnownBitsImpl.
+class GISelKnownBitsAnalysis : public MachineFunctionPass {
+  std::unique_ptr<GISelKnownBits> Info;
+
+public:
+  static char ID;
+  GISelKnownBitsAnalysis() : MachineFunctionPass(ID) {
+    initializeGISelKnownBitsAnalysisPass(*PassRegistry::getPassRegistry());
+  }
+  GISelKnownBits &get(MachineFunction &MF) {
+    if (!Info)
+      Info = std::make_unique<GISelKnownBits>(MF);
+    return *Info.get();
+  }
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+  bool runOnMachineFunction(MachineFunction &MF) override;
+  void releaseMemory() override { Info.reset(); }
+};
+} // namespace llvm
+
+#endif // ifdef