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12bce03eea
In various circumstances, when we clobber a register there may be alternative locations that the value is live in. The classic example would be a value loaded from the stack, and then clobbered: the value is still available on the stack. InstrRefBasedLDV was coping with this at block starts where it's forced to pick a location, however it wasn't searching for alternative locations when values were clobbered. This patch notifies the "Transfer Tracker" object when clobbers occur, and it's able to find alternatives and issue DBG_VALUEs for that location. See: the added test. Differential Revision: https://reviews.llvm.org/D88405
108 lines
3.4 KiB
C++
108 lines
3.4 KiB
C++
//===- LiveDebugValues.cpp - Tracking Debug Value MIs ---------------------===//
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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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#include "LiveDebugValues.h"
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#include "llvm/CodeGen/MachineBasicBlock.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Target/TargetMachine.h"
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/// \file LiveDebugValues.cpp
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///
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/// The LiveDebugValues pass extends the range of variable locations
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/// (specified by DBG_VALUE instructions) from single blocks to successors
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/// and any other code locations where the variable location is valid.
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/// There are currently two implementations: the "VarLoc" implementation
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/// explicitly tracks the location of a variable, while the "InstrRef"
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/// implementation tracks the values defined by instructions through locations.
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///
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/// This file implements neither; it merely registers the pass, allows the
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/// user to pick which implementation will be used to propagate variable
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/// locations.
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#define DEBUG_TYPE "livedebugvalues"
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using namespace llvm;
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static cl::opt<bool>
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ForceInstrRefLDV("force-instr-ref-livedebugvalues", cl::Hidden,
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cl::desc("Use instruction-ref based LiveDebugValues with "
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"normal DBG_VALUE inputs"),
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cl::init(false));
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/// Generic LiveDebugValues pass. Calls through to VarLocBasedLDV or
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/// InstrRefBasedLDV to perform location propagation, via the LDVImpl
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/// base class.
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class LiveDebugValues : public MachineFunctionPass {
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public:
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static char ID;
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LiveDebugValues();
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~LiveDebugValues() {
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if (TheImpl)
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delete TheImpl;
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}
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/// Calculate the liveness information for the given machine function.
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bool runOnMachineFunction(MachineFunction &MF) override;
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MachineFunctionProperties getRequiredProperties() const override {
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return MachineFunctionProperties().set(
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MachineFunctionProperties::Property::NoVRegs);
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesCFG();
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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private:
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LDVImpl *TheImpl;
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TargetPassConfig *TPC;
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};
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char LiveDebugValues::ID = 0;
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char &llvm::LiveDebugValuesID = LiveDebugValues::ID;
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INITIALIZE_PASS(LiveDebugValues, DEBUG_TYPE, "Live DEBUG_VALUE analysis", false,
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false)
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/// Default construct and initialize the pass.
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LiveDebugValues::LiveDebugValues() : MachineFunctionPass(ID) {
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initializeLiveDebugValuesPass(*PassRegistry::getPassRegistry());
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TheImpl = nullptr;
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}
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bool LiveDebugValues::runOnMachineFunction(MachineFunction &MF) {
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if (!TheImpl) {
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TPC = getAnalysisIfAvailable<TargetPassConfig>();
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bool InstrRefBased = false;
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if (TPC) {
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auto &TM = TPC->getTM<TargetMachine>();
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InstrRefBased = TM.Options.ValueTrackingVariableLocations;
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}
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// Allow the user to force selection of InstrRef LDV.
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InstrRefBased |= ForceInstrRefLDV;
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if (InstrRefBased)
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TheImpl = llvm::makeInstrRefBasedLiveDebugValues();
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else
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TheImpl = llvm::makeVarLocBasedLiveDebugValues();
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}
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return TheImpl->ExtendRanges(MF, TPC);
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}
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