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This optional register liveness analysis pass can be enabled with either -enable-stackmap-liveness, -enable-patchpoint-liveness, or both. The pass traverses each basic block in a machine function. For each basic block the instructions are processed in reversed order and if a patchpoint or stackmap instruction is encountered the current live-out register set is encoded as a register mask and attached to the instruction. Later on during stackmap generation the live-out register mask is processed and also emitted as part of the stackmap. This information is optional and intended for optimization purposes only. This will enable a client of the stackmap to reason about the registers it can use and which registers need to be preserved. Reviewed by Andy git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197317 91177308-0d34-0410-b5e6-96231b3b80d8
66 lines
2.3 KiB
C++
66 lines
2.3 KiB
C++
//===--- StackMapLivenessAnalysis - StackMap Liveness Analysis --*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass calculates the liveness for each basic block in a function and
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// attaches the register live-out information to a stackmap or patchpoint
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// intrinsic if present.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_STACKMAP_LIVENESS_ANALYSIS_H
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#define LLVM_CODEGEN_STACKMAP_LIVENESS_ANALYSIS_H
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#include "llvm/CodeGen/LivePhysRegs.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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namespace llvm {
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/// \brief This pass calculates the liveness information for each basic block in
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/// a function and attaches the register live-out information to a stackmap or
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/// patchpoint intrinsic if present.
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///
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/// This is an optional pass that has to be explicitly enabled via the
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/// -enable-stackmap-liveness and/or -enable-patchpoint-liveness flag. The pass
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/// skips functions that don't have any stackmap or patchpoint intrinsics. The
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/// information provided by this pass is optional and not required by the
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/// aformentioned intrinsics to function.
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class StackMapLiveness : public MachineFunctionPass {
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MachineFunction *MF;
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const TargetRegisterInfo *TRI;
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LivePhysRegs LiveRegs;
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public:
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static char ID;
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/// \brief Default construct and initialize the pass.
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StackMapLiveness();
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/// \brief Tell the pass manager which passes we depend on and what
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/// information we preserve.
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virtual void getAnalysisUsage(AnalysisUsage &AU) const;
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/// \brief Calculate the liveness information for the given machine function.
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virtual bool runOnMachineFunction(MachineFunction &MF);
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private:
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/// \brief Performs the actual liveness calculation for the function.
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bool calculateLiveness();
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/// \brief Add the current register live set to the instruction.
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void addLiveOutSetToMI(MachineInstr &MI);
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/// \brief Create a register mask and initialize it with the registers from
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/// the register live set.
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uint32_t *createRegisterMask() const;
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};
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} // llvm namespace
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#endif // LLVM_CODEGEN_STACKMAP_LIVENESS_ANALYSIS_H
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