708cbda577
This reapplies54a61c94f9, its follow up in547b712500, which were reverted95fe61e639. Original commit message: VarLoc based LiveDebugValues will abandon variable location propagation if there are too many blocks and variable assignments in the function. If it didn't, and we had (say) 1000 blocks and 1000 variables in scope, we'd end up with 1 million DBG_VALUEs just at the start of blocks. Instruction-referencing LiveDebugValues should honour this limitation too (because the same limitation applies to it). Hoist the relevant command line options into LiveDebugValues.cpp and pass it down into the implementation classes as an argument to ExtendRanges. I've duplicated all the run-lines in live-debug-values-cutoffs.mir to have an instruction-referencing flavour. Differential Revision: https://reviews.llvm.org/D107823
120 lines
4.0 KiB
C++
120 lines
4.0 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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// Options to prevent pathological compile-time behavior. If InputBBLimit and
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// InputDbgValueLimit are both exceeded, range extension is disabled.
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static cl::opt<unsigned> InputBBLimit(
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"livedebugvalues-input-bb-limit",
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cl::desc("Maximum input basic blocks before DBG_VALUE limit applies"),
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cl::init(10000), cl::Hidden);
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static cl::opt<unsigned> InputDbgValueLimit(
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"livedebugvalues-input-dbg-value-limit",
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cl::desc(
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"Maximum input DBG_VALUE insts supported by debug range extension"),
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cl::init(50000), cl::Hidden);
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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, InputBBLimit, InputDbgValueLimit);
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}
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