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https://github.com/capstone-engine/llvm-capstone.git
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69e75ae695
This fixes what I consider to be an API flaw I've tripped over multiple times. The point this is constructed isn't well defined, so depending on where this is first called, you can conclude different information based on the MachineFunction. For example, the AMDGPU implementation inspected the MachineFrameInfo on construction for the stack objects and if the frame has calls. This kind of worked in SelectionDAG which visited all allocas up front, but broke in GlobalISel which hasn't visited any of the IR when arguments are lowered. I've run into similar problems before with the MIR parser and trying to make use of other MachineFunction fields, so I think it's best to just categorically disallow dependency on the MachineFunction state in the constructor and to always construct this at the same time as the MachineFunction itself. A missing feature I still could use is a way to access an custom analysis pass on the IR here.
93 lines
3.5 KiB
C++
93 lines
3.5 KiB
C++
//===-- ResetMachineFunctionPass.cpp - Reset Machine Function ----*- 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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/// This file implements a pass that will conditionally reset a machine
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/// function as if it was just created. This is used to provide a fallback
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/// mechanism when GlobalISel fails, thus the condition for the reset to
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/// happen is that the MachineFunction has the FailedISel property.
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/ScopeExit.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/CodeGen/StackProtector.h"
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#include "llvm/IR/DiagnosticInfo.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/Support/Debug.h"
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using namespace llvm;
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#define DEBUG_TYPE "reset-machine-function"
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STATISTIC(NumFunctionsReset, "Number of functions reset");
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STATISTIC(NumFunctionsVisited, "Number of functions visited");
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namespace {
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class ResetMachineFunction : public MachineFunctionPass {
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/// Tells whether or not this pass should emit a fallback
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/// diagnostic when it resets a function.
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bool EmitFallbackDiag;
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/// Whether we should abort immediately instead of resetting the function.
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bool AbortOnFailedISel;
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public:
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static char ID; // Pass identification, replacement for typeid
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ResetMachineFunction(bool EmitFallbackDiag = false,
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bool AbortOnFailedISel = false)
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: MachineFunctionPass(ID), EmitFallbackDiag(EmitFallbackDiag),
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AbortOnFailedISel(AbortOnFailedISel) {}
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StringRef getPassName() const override { return "ResetMachineFunction"; }
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.addPreserved<StackProtector>();
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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bool runOnMachineFunction(MachineFunction &MF) override {
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++NumFunctionsVisited;
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// No matter what happened, whether we successfully selected the function
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// or not, nothing is going to use the vreg types after us. Make sure they
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// disappear.
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auto ClearVRegTypesOnReturn =
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make_scope_exit([&MF]() { MF.getRegInfo().clearVirtRegTypes(); });
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if (MF.getProperties().hasProperty(
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MachineFunctionProperties::Property::FailedISel)) {
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if (AbortOnFailedISel)
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report_fatal_error("Instruction selection failed");
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LLVM_DEBUG(dbgs() << "Resetting: " << MF.getName() << '\n');
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++NumFunctionsReset;
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MF.reset();
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MF.initTargetMachineFunctionInfo(MF.getSubtarget());
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if (EmitFallbackDiag) {
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const Function &F = MF.getFunction();
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DiagnosticInfoISelFallback DiagFallback(F);
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F.getContext().diagnose(DiagFallback);
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}
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return true;
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}
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return false;
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}
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};
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} // end anonymous namespace
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char ResetMachineFunction::ID = 0;
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INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE,
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"Reset machine function if ISel failed", false, false)
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MachineFunctionPass *
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llvm::createResetMachineFunctionPass(bool EmitFallbackDiag = false,
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bool AbortOnFailedISel = false) {
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return new ResetMachineFunction(EmitFallbackDiag, AbortOnFailedISel);
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}
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