6a605b97a2
This feature was previously controlled by a TargetOptions flag, and I
figured that codegen::InitTargetOptionsFromCodeGenFlags would default it
to "on" for all frontends. Enabling by default was discussed here:
https://lists.llvm.org/pipermail/llvm-dev/2021-November/153653.html
and originally supposed to happen in 3c04507088, but it didn't actually
take effect, as it turns out frontends initialize TargetOptions themselves.
This patch moves the flag from a TargetOptions flag to a global flag to
CodeGen, where it isn't immediately affected by the frontend being used.
Hopefully this will actually cause instr-ref to be on by default on x86_64
now!
This patch is easily reverted, and chances of turbulence are moderately
high. If you need to revert, please consider instead commenting out the
'return true' part of llvm::debuginfoShouldUseDebugInstrRef to turn the
feature off, and dropping me an email.
Differential Revision: https://reviews.llvm.org/D116821
134 lines
4.7 KiB
C++
134 lines
4.7 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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static cl::opt<cl::boolOrDefault> ValueTrackingVariableLocations(
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"experimental-debug-variable-locations",
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cl::desc("Use experimental new value-tracking variable locations"));
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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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namespace {
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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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/// 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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std::unique_ptr<LDVImpl> InstrRefImpl;
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std::unique_ptr<LDVImpl> VarLocImpl;
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TargetPassConfig *TPC;
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MachineDominatorTree MDT;
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};
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} // namespace
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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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InstrRefImpl =
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std::unique_ptr<LDVImpl>(llvm::makeInstrRefBasedLiveDebugValues());
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VarLocImpl = std::unique_ptr<LDVImpl>(llvm::makeVarLocBasedLiveDebugValues());
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}
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bool LiveDebugValues::runOnMachineFunction(MachineFunction &MF) {
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bool InstrRefBased = MF.useDebugInstrRef();
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// Allow the user to force selection of InstrRef LDV.
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InstrRefBased |= ForceInstrRefLDV;
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TPC = getAnalysisIfAvailable<TargetPassConfig>();
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LDVImpl *TheImpl = &*VarLocImpl;
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MachineDominatorTree *DomTree = nullptr;
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if (InstrRefBased) {
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DomTree = &MDT;
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MDT.calculate(MF);
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TheImpl = &*InstrRefImpl;
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}
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return TheImpl->ExtendRanges(MF, DomTree, TPC, InputBBLimit,
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InputDbgValueLimit);
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}
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bool llvm::debuginfoShouldUseDebugInstrRef(const Triple &T) {
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// Enable by default on x86_64, disable if explicitly turned off on cmdline.
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if (T.getArch() == llvm::Triple::x86_64 &&
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ValueTrackingVariableLocations != cl::boolOrDefault::BOU_FALSE)
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return true;
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// Otherwise: enable if explicitly requestedo n command line.
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return ValueTrackingVariableLocations == cl::boolOrDefault::BOU_TRUE;
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}
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