8f28e8069c
Generate store immediate instruction when CPUv4 is enabled.
For example:
$ cat test.c
struct foo {
unsigned char b;
unsigned short h;
unsigned int w;
unsigned long d;
};
void bar(volatile struct foo *p) {
p->b = 1;
p->h = 2;
p->w = 3;
p->d = 4;
}
$ clang -O2 --target=bpf -mcpu=v4 test.c -c -o - | llvm-objdump -d -
...
0000000000000000 <bar>:
0: 72 01 00 00 01 00 00 00 *(u8 *)(r1 + 0x0) = 0x1
1: 6a 01 02 00 02 00 00 00 *(u16 *)(r1 + 0x2) = 0x2
2: 62 01 04 00 03 00 00 00 *(u32 *)(r1 + 0x4) = 0x3
3: 7a 01 08 00 04 00 00 00 *(u64 *)(r1 + 0x8) = 0x4
4: 95 00 00 00 00 00 00 00 exit
Take special care to:
- apply `BPFMISimplifyPatchable::checkADDrr` rewrite for BPF_ST
- validate immediate value when BPF_ST write is 64-bit:
BPF interprets `(BPF_ST | BPF_MEM | BPF_DW)` writes as writes with
sign extension. Thus it is fine to generate such write when
immediate is -1, but it is incorrect to generate such write when
immediate is +0xffff_ffff.
This commit was previously reverted in e66affa17e32.
The reason for revert was an unrelated bug in BPF backend,
triggered by test case added in this commit if LLVM is built
with LLVM_ENABLE_EXPENSIVE_CHECKS.
The bug was fixed in D157806.
Differential Revision: https://reviews.llvm.org/D140804
101 lines
3.2 KiB
C++
101 lines
3.2 KiB
C++
//===-- BPFSubtarget.h - Define Subtarget for the BPF -----------*- 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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// This file declares the BPF specific subclass of TargetSubtargetInfo.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_BPF_BPFSUBTARGET_H
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#define LLVM_LIB_TARGET_BPF_BPFSUBTARGET_H
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#include "BPFFrameLowering.h"
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#include "BPFISelLowering.h"
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#include "BPFInstrInfo.h"
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#include "BPFSelectionDAGInfo.h"
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#include "llvm/CodeGen/SelectionDAGTargetInfo.h"
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#include "llvm/CodeGen/TargetSubtargetInfo.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/Target/TargetMachine.h"
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#define GET_SUBTARGETINFO_HEADER
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#include "BPFGenSubtargetInfo.inc"
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namespace llvm {
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class StringRef;
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class BPFSubtarget : public BPFGenSubtargetInfo {
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virtual void anchor();
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BPFInstrInfo InstrInfo;
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BPFFrameLowering FrameLowering;
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BPFTargetLowering TLInfo;
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BPFSelectionDAGInfo TSInfo;
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private:
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void initializeEnvironment();
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void initSubtargetFeatures(StringRef CPU, StringRef FS);
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protected:
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// unused
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bool isDummyMode;
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// whether the cpu supports jmp ext
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bool HasJmpExt;
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// whether the cpu supports jmp32 ext.
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// NOTE: jmp32 is not enabled when alu32 enabled.
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bool HasJmp32;
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// whether the cpu supports alu32 instructions.
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bool HasAlu32;
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// whether we should enable MCAsmInfo DwarfUsesRelocationsAcrossSections
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bool UseDwarfRIS;
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// whether cpu v4 insns are enabled.
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bool HasLdsx, HasMovsx, HasBswap, HasSdivSmod, HasGotol, HasStoreImm;
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public:
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// This constructor initializes the data members to match that
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// of the specified triple.
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BPFSubtarget(const Triple &TT, const std::string &CPU, const std::string &FS,
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const TargetMachine &TM);
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BPFSubtarget &initializeSubtargetDependencies(StringRef CPU, StringRef FS);
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// ParseSubtargetFeatures - Parses features string setting specified
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// subtarget options. Definition of function is auto generated by tblgen.
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void ParseSubtargetFeatures(StringRef CPU, StringRef TuneCPU, StringRef FS);
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bool getHasJmpExt() const { return HasJmpExt; }
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bool getHasJmp32() const { return HasJmp32; }
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bool getHasAlu32() const { return HasAlu32; }
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bool getUseDwarfRIS() const { return UseDwarfRIS; }
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bool hasLdsx() const { return HasLdsx; }
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bool hasMovsx() const { return HasMovsx; }
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bool hasBswap() const { return HasBswap; }
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bool hasSdivSmod() const { return HasSdivSmod; }
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bool hasGotol() const { return HasGotol; }
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bool hasStoreImm() const { return HasStoreImm; }
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const BPFInstrInfo *getInstrInfo() const override { return &InstrInfo; }
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const BPFFrameLowering *getFrameLowering() const override {
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return &FrameLowering;
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}
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const BPFTargetLowering *getTargetLowering() const override {
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return &TLInfo;
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}
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const BPFSelectionDAGInfo *getSelectionDAGInfo() const override {
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return &TSInfo;
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}
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const TargetRegisterInfo *getRegisterInfo() const override {
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return &InstrInfo.getRegisterInfo();
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}
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};
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} // End llvm namespace
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#endif
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