208 lines
8.1 KiB
C++
208 lines
8.1 KiB
C++
//===- llvm/CodeGen/GlobalISel/GISelValueTracking.h -------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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/// \file
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/// Provides analysis for querying information about KnownBits during GISel
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/// passes.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_GLOBALISEL_GISELVALUETRACKING_H
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#define LLVM_CODEGEN_GLOBALISEL_GISELVALUETRACKING_H
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#include "llvm/ADT/APFloat.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/CodeGen/GlobalISel/GISelChangeObserver.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/Register.h"
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#include "llvm/IR/InstrTypes.h"
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#include "llvm/IR/PassManager.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/KnownBits.h"
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#include "llvm/Support/KnownFPClass.h"
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namespace llvm {
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class TargetLowering;
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class DataLayout;
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class LLVM_ABI GISelValueTracking : public GISelChangeObserver {
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MachineFunction &MF;
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MachineRegisterInfo &MRI;
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const TargetLowering &TL;
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const DataLayout &DL;
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unsigned MaxDepth;
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void computeKnownBitsMin(Register Src0, Register Src1, KnownBits &Known,
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const APInt &DemandedElts, unsigned Depth = 0);
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unsigned computeNumSignBitsMin(Register Src0, Register Src1,
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const APInt &DemandedElts, unsigned Depth = 0);
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void computeKnownFPClass(Register R, KnownFPClass &Known,
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FPClassTest InterestedClasses, unsigned Depth);
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void computeKnownFPClassForFPTrunc(const MachineInstr &MI,
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const APInt &DemandedElts,
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FPClassTest InterestedClasses,
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KnownFPClass &Known, unsigned Depth);
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void computeKnownFPClass(Register R, const APInt &DemandedElts,
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FPClassTest InterestedClasses, KnownFPClass &Known,
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unsigned Depth);
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public:
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GISelValueTracking(MachineFunction &MF, unsigned MaxDepth = 6);
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~GISelValueTracking() override = default;
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const MachineFunction &getMachineFunction() const { return MF; }
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const DataLayout &getDataLayout() const { return DL; }
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void computeKnownBitsImpl(Register R, KnownBits &Known,
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const APInt &DemandedElts, unsigned Depth = 0);
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unsigned computeNumSignBits(Register R, const APInt &DemandedElts,
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unsigned Depth = 0);
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unsigned computeNumSignBits(Register R, unsigned Depth = 0);
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// KnownBitsAPI
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KnownBits getKnownBits(Register R);
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KnownBits getKnownBits(Register R, const APInt &DemandedElts,
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unsigned Depth = 0);
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// Calls getKnownBits for first operand def of MI.
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KnownBits getKnownBits(MachineInstr &MI);
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APInt getKnownZeroes(Register R);
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APInt getKnownOnes(Register R);
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/// \return true if 'V & Mask' is known to be zero in DemandedElts. We use
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/// this predicate to simplify operations downstream.
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/// Mask is known to be zero for bits that V cannot have.
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bool maskedValueIsZero(Register Val, const APInt &Mask) {
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return Mask.isSubsetOf(getKnownBits(Val).Zero);
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}
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/// \return true if the sign bit of Op is known to be zero. We use this
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/// predicate to simplify operations downstream.
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bool signBitIsZero(Register Op);
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static void computeKnownBitsForAlignment(KnownBits &Known, Align Alignment) {
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// The low bits are known zero if the pointer is aligned.
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Known.Zero.setLowBits(Log2(Alignment));
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}
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/// \return The known alignment for the pointer-like value \p R.
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Align computeKnownAlignment(Register R, unsigned Depth = 0);
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/// If a G_SHL/G_ASHR/G_LSHR node with shift operand \p R has shift amounts
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/// that are all less than the element bit-width of the shift node, return the
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/// valid constant range.
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std::optional<ConstantRange>
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getValidShiftAmountRange(Register R, const APInt &DemandedElts,
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unsigned Depth);
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/// If a G_SHL/G_ASHR/G_LSHR node with shift operand \p R has shift amounts
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/// that are all less than the element bit-width of the shift node, return the
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/// minimum possible value.
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std::optional<uint64_t> getValidMinimumShiftAmount(Register R,
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const APInt &DemandedElts,
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unsigned Depth = 0);
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/// Determine which floating-point classes are valid for \p V, and return them
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/// in KnownFPClass bit sets.
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///
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/// This function is defined on values with floating-point type, values
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/// vectors of floating-point type, and arrays of floating-point type.
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/// \p InterestedClasses is a compile time optimization hint for which
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/// floating point classes should be queried. Queries not specified in \p
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/// InterestedClasses should be reliable if they are determined during the
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/// query.
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KnownFPClass computeKnownFPClass(Register R, const APInt &DemandedElts,
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FPClassTest InterestedClasses,
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unsigned Depth);
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KnownFPClass computeKnownFPClass(Register R,
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FPClassTest InterestedClasses = fcAllFlags,
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unsigned Depth = 0);
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/// Wrapper to account for known fast math flags at the use instruction.
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KnownFPClass computeKnownFPClass(Register R, const APInt &DemandedElts,
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uint32_t Flags,
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FPClassTest InterestedClasses,
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unsigned Depth);
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KnownFPClass computeKnownFPClass(Register R, uint32_t Flags,
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FPClassTest InterestedClasses,
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unsigned Depth);
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/// Returns true if \p Val can be assumed to never be a NaN. If \p SNaN is
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/// true, this returns whether \p Val can be assumed to never be a signaling
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/// NaN.
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bool isKnownNeverNaN(Register Val, bool SNaN = false);
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/// Returns true if \p Val can be assumed to never be a signaling NaN.
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bool isKnownNeverSNaN(Register Val) { return isKnownNeverNaN(Val, true); }
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// Observer API. No-op for non-caching implementation.
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void erasingInstr(MachineInstr &MI) override {}
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void createdInstr(MachineInstr &MI) override {}
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void changingInstr(MachineInstr &MI) override {}
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void changedInstr(MachineInstr &MI) override {}
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protected:
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unsigned getMaxDepth() const { return MaxDepth; }
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};
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/// To use KnownBitsInfo analysis in a pass,
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/// KnownBitsInfo &Info = getAnalysis<GISelValueTrackingInfoAnalysis>().get(MF);
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/// Add to observer if the Info is caching.
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/// WrapperObserver.addObserver(Info);
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/// Eventually add other features such as caching/ser/deserializing
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/// to MIR etc. Those implementations can derive from GISelValueTracking
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/// and override computeKnownBitsImpl.
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class LLVM_ABI GISelValueTrackingAnalysisLegacy : public MachineFunctionPass {
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std::unique_ptr<GISelValueTracking> Info;
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public:
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static char ID;
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GISelValueTrackingAnalysisLegacy() : MachineFunctionPass(ID) {}
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GISelValueTracking &get(MachineFunction &MF);
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void getAnalysisUsage(AnalysisUsage &AU) const override;
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bool runOnMachineFunction(MachineFunction &MF) override;
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void releaseMemory() override { Info.reset(); }
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};
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class GISelValueTrackingAnalysis
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: public AnalysisInfoMixin<GISelValueTrackingAnalysis> {
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friend AnalysisInfoMixin<GISelValueTrackingAnalysis>;
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LLVM_ABI static AnalysisKey Key;
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public:
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using Result = GISelValueTracking;
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LLVM_ABI Result run(MachineFunction &MF,
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MachineFunctionAnalysisManager &MFAM);
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};
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class GISelValueTrackingPrinterPass
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: public RequiredPassInfoMixin<GISelValueTrackingPrinterPass> {
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raw_ostream &OS;
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public:
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GISelValueTrackingPrinterPass(raw_ostream &OS) : OS(OS) {}
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LLVM_ABI PreservedAnalyses run(MachineFunction &MF,
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MachineFunctionAnalysisManager &MFAM);
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};
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} // namespace llvm
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#endif // LLVM_CODEGEN_GLOBALISEL_GISELVALUETRACKING_H
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