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a2b88794ad
This patch adds TargetStackID::WasmLocal. This stack holds locations of values that are only addressable by name -- not via a pointer to memory. For the WebAssembly target, these objects are lowered to WebAssembly local variables, which are managed by the WebAssembly run-time and are not addressable by linear memory. For the WebAssembly target IR indicates that an AllocaInst should be put on TargetStackID::WasmLocal by putting it in the non-integral address space WASM_ADDRESS_SPACE_WASM_VAR, with value 1. SROA will mostly lift these allocations to SSA locals, but any alloca that reaches instruction selection (usually in non-optimized builds) will be assigned the new TargetStackID there. Loads and stores to those values are transformed to new WebAssemblyISD::LOCAL_GET / WebAssemblyISD::LOCAL_SET nodes, which then lower to the type-specific LOCAL_GET_I32 etc instructions via tablegen patterns. Differential Revision: https://reviews.llvm.org/D101140
81 lines
3.3 KiB
C++
81 lines
3.3 KiB
C++
// WebAssemblyFrameLowering.h - TargetFrameLowering for WebAssembly -*- 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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///
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/// \file
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/// This class implements WebAssembly-specific bits of
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/// TargetFrameLowering class.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYFRAMELOWERING_H
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#define LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYFRAMELOWERING_H
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#include "llvm/CodeGen/TargetFrameLowering.h"
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namespace llvm {
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class WebAssemblyFrameLowering final : public TargetFrameLowering {
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public:
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/// Size of the red zone for the user stack (leaf functions can use this much
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/// space below the stack pointer without writing it back to __stack_pointer
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/// global).
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// TODO: (ABI) Revisit and decide how large it should be.
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static const size_t RedZoneSize = 128;
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WebAssemblyFrameLowering()
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: TargetFrameLowering(StackGrowsDown, /*StackAlignment=*/Align(16),
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/*LocalAreaOffset=*/0,
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/*TransientStackAlignment=*/Align(16),
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/*StackRealignable=*/true) {}
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MachineBasicBlock::iterator
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eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I) const override;
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/// These methods insert prolog and epilog code into the function.
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void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
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void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
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bool hasFP(const MachineFunction &MF) const override;
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bool hasReservedCallFrame(const MachineFunction &MF) const override;
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bool isSupportedStackID(TargetStackID::Value ID) const override;
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DwarfFrameBase getDwarfFrameBase(const MachineFunction &MF) const override;
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bool needsPrologForEH(const MachineFunction &MF) const;
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/// Write SP back to __stack_pointer global.
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void writeSPToGlobal(unsigned SrcReg, MachineFunction &MF,
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MachineBasicBlock &MBB,
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MachineBasicBlock::iterator &InsertStore,
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const DebugLoc &DL) const;
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// Returns the index of the WebAssembly local to which the stack object
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// FrameIndex in MF should be allocated, or None.
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static Optional<unsigned> getLocalForStackObject(MachineFunction &MF,
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int FrameIndex);
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static unsigned getSPReg(const MachineFunction &MF);
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static unsigned getFPReg(const MachineFunction &MF);
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static unsigned getOpcConst(const MachineFunction &MF);
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static unsigned getOpcAdd(const MachineFunction &MF);
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static unsigned getOpcSub(const MachineFunction &MF);
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static unsigned getOpcAnd(const MachineFunction &MF);
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static unsigned getOpcGlobGet(const MachineFunction &MF);
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static unsigned getOpcGlobSet(const MachineFunction &MF);
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private:
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bool hasBP(const MachineFunction &MF) const;
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bool needsSPForLocalFrame(const MachineFunction &MF) const;
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bool needsSP(const MachineFunction &MF) const;
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bool needsSPWriteback(const MachineFunction &MF) const;
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};
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} // end namespace llvm
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#endif
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