llvm-project/llvm/lib/Target/RISCV/RISCVFrameLowering.h
Wang Pengcheng 3ac9fe69f7
[RISCV] CodeGen of RVE and ilp32e/lp64e ABIs (#76777)
This commit includes the necessary changes to clang and LLVM to support
codegen of `RVE` and the `ilp32e`/`lp64e` ABIs.

The differences between `RVE` and `RVI` are:
* `RVE` reduces the integer register count to 16(x0-x16).
* The ABI should be `ilp32e` for 32 bits and `lp64e` for 64 bits.

`RVE` can be combined with all current standard extensions.

The central changes in ilp32e/lp64e ABI, compared to ilp32/lp64 are:
* Only 6 integer argument registers (rather than 8).
* Only 2 callee-saved registers (rather than 12).
* A Stack Alignment of 32bits (rather than 128bits).
* ilp32e isn't compatible with D ISA extension.

If `ilp32e` or `lp64` is used with an ISA that has any of the registers
x16-x31 and f0-f31, then these registers are considered temporaries.

To be compatible with the implementation of ilp32e in GCC, we don't use
aligned registers to pass variadic arguments and set stack alignment\
to 4-bytes for types with length of 2*XLEN.

FastCC is also supported on RVE, while GHC isn't since there is only one
avaiable register.

Differential Revision: https://reviews.llvm.org/D70401
2024-01-16 20:44:30 +08:00

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3.6 KiB
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//===-- RISCVFrameLowering.h - Define frame lowering for RISC-V -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This class implements RISC-V specific bits of TargetFrameLowering class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TARGET_RISCV_RISCVFRAMELOWERING_H
#define LLVM_LIB_TARGET_RISCV_RISCVFRAMELOWERING_H
#include "llvm/CodeGen/TargetFrameLowering.h"
#include "llvm/Support/TypeSize.h"
namespace llvm {
class RISCVSubtarget;
class RISCVFrameLowering : public TargetFrameLowering {
public:
explicit RISCVFrameLowering(const RISCVSubtarget &STI);
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
uint64_t getStackSizeWithRVVPadding(const MachineFunction &MF) const;
StackOffset getFrameIndexReference(const MachineFunction &MF, int FI,
Register &FrameReg) const override;
void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
RegScavenger *RS) const override;
void processFunctionBeforeFrameFinalized(MachineFunction &MF,
RegScavenger *RS) const override;
bool hasFP(const MachineFunction &MF) const override;
bool hasBP(const MachineFunction &MF) const;
bool hasReservedCallFrame(const MachineFunction &MF) const override;
MachineBasicBlock::iterator
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI) const override;
bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
ArrayRef<CalleeSavedInfo> CSI,
const TargetRegisterInfo *TRI) const override;
bool
restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
MutableArrayRef<CalleeSavedInfo> CSI,
const TargetRegisterInfo *TRI) const override;
// Get the first stack adjustment amount for SplitSPAdjust.
// Return 0 if we don't want to split the SP adjustment in prologue and
// epilogue.
uint64_t getFirstSPAdjustAmount(const MachineFunction &MF) const;
bool canUseAsPrologue(const MachineBasicBlock &MBB) const override;
bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override;
bool enableShrinkWrapping(const MachineFunction &MF) const override;
bool isSupportedStackID(TargetStackID::Value ID) const override;
TargetStackID::Value getStackIDForScalableVectors() const override;
bool isStackIdSafeForLocalArea(unsigned StackId) const override {
// We don't support putting RISC-V Vector objects into the pre-allocated
// local frame block at the moment.
return StackId != TargetStackID::ScalableVector;
}
protected:
const RISCVSubtarget &STI;
private:
void determineFrameLayout(MachineFunction &MF) const;
void adjustStackForRVV(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
int64_t Amount, MachineInstr::MIFlag Flag) const;
std::pair<int64_t, Align>
assignRVVStackObjectOffsets(MachineFunction &MF) const;
};
} // namespace llvm
#endif