| //===-- RISCVMCExpr.cpp - RISCV specific MC expression classes ------------===// |
| // |
| // 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 file contains the implementation of the assembly expression modifiers |
| // accepted by the RISCV architecture (e.g. ":lo12:", ":gottprel_g1:", ...). |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "RISCV.h" |
| #include "RISCVMCExpr.h" |
| #include "RISCVFixupKinds.h" |
| #include "llvm/MC/MCAssembler.h" |
| #include "llvm/MC/MCContext.h" |
| #include "llvm/MC/MCStreamer.h" |
| #include "llvm/MC/MCSymbolELF.h" |
| #include "llvm/MC/MCValue.h" |
| #include "llvm/Support/ErrorHandling.h" |
| |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "riscvmcexpr" |
| |
| const RISCVMCExpr *RISCVMCExpr::create(const MCExpr *Expr, VariantKind Kind, |
| MCContext &Ctx) { |
| return new (Ctx) RISCVMCExpr(Expr, Kind); |
| } |
| |
| void RISCVMCExpr::printImpl(raw_ostream &OS, const MCAsmInfo *MAI) const { |
| bool HasVariant = |
| ((getKind() != VK_RISCV_None) && (getKind() != VK_RISCV_CALL)); |
| if (HasVariant) |
| OS << '%' << getVariantKindName(getKind()) << '('; |
| Expr->print(OS, MAI); |
| if (HasVariant) |
| OS << ')'; |
| } |
| |
| const MCFixup *RISCVMCExpr::getPCRelHiFixup() const { |
| MCValue AUIPCLoc; |
| if (!getSubExpr()->evaluateAsRelocatable(AUIPCLoc, nullptr, nullptr)) |
| return nullptr; |
| |
| const MCSymbolRefExpr *AUIPCSRE = AUIPCLoc.getSymA(); |
| if (!AUIPCSRE) |
| return nullptr; |
| |
| const MCSymbol *AUIPCSymbol = &AUIPCSRE->getSymbol(); |
| const auto *DF = dyn_cast_or_null<MCDataFragment>(AUIPCSymbol->getFragment()); |
| |
| if (!DF) |
| return nullptr; |
| |
| uint64_t Offset = AUIPCSymbol->getOffset(); |
| if (DF->getContents().size() == Offset) { |
| DF = dyn_cast_or_null<MCDataFragment>(DF->getNextNode()); |
| if (!DF) |
| return nullptr; |
| Offset = 0; |
| } |
| |
| for (const MCFixup &F : DF->getFixups()) { |
| if (F.getOffset() != Offset) |
| continue; |
| |
| switch ((unsigned)F.getKind()) { |
| default: |
| continue; |
| case RISCV::fixup_riscv_got_hi20: |
| case RISCV::fixup_riscv_pcrel_hi20: |
| return &F; |
| } |
| } |
| |
| return nullptr; |
| } |
| |
| bool RISCVMCExpr::evaluatePCRelLo(MCValue &Res, const MCAsmLayout *Layout, |
| const MCFixup *Fixup) const { |
| // VK_RISCV_PCREL_LO has to be handled specially. The MCExpr inside is |
| // actually the location of a auipc instruction with a VK_RISCV_PCREL_HI fixup |
| // pointing to the real target. We need to generate an MCValue in the form of |
| // (<real target> + <offset from this fixup to the auipc fixup>). The Fixup |
| // is pcrel relative to the VK_RISCV_PCREL_LO fixup, so we need to add the |
| // offset to the VK_RISCV_PCREL_HI Fixup from VK_RISCV_PCREL_LO to correct. |
| MCValue AUIPCLoc; |
| if (!getSubExpr()->evaluateAsValue(AUIPCLoc, *Layout)) |
| return false; |
| |
| const MCSymbolRefExpr *AUIPCSRE = AUIPCLoc.getSymA(); |
| // Don't try to evaluate %pcrel_hi/%pcrel_lo pairs that cross fragment |
| // boundries. |
| if (!AUIPCSRE || |
| findAssociatedFragment() != AUIPCSRE->findAssociatedFragment()) |
| return false; |
| |
| const MCSymbol *AUIPCSymbol = &AUIPCSRE->getSymbol(); |
| if (!AUIPCSymbol) |
| return false; |
| |
| const MCFixup *TargetFixup = getPCRelHiFixup(); |
| if (!TargetFixup) |
| return false; |
| |
| if ((unsigned)TargetFixup->getKind() != RISCV::fixup_riscv_pcrel_hi20) |
| return false; |
| |
| MCValue Target; |
| if (!TargetFixup->getValue()->evaluateAsValue(Target, *Layout)) |
| return false; |
| |
| if (!Target.getSymA() || !Target.getSymA()->getSymbol().isInSection()) |
| return false; |
| |
| if (&Target.getSymA()->getSymbol().getSection() != |
| findAssociatedFragment()->getParent()) |
| return false; |
| |
| uint64_t AUIPCOffset = AUIPCSymbol->getOffset(); |
| |
| Res = MCValue::get(Target.getSymA(), nullptr, |
| Target.getConstant() + (Fixup->getOffset() - AUIPCOffset)); |
| return true; |
| } |
| |
| bool RISCVMCExpr::evaluateAsRelocatableImpl(MCValue &Res, |
| const MCAsmLayout *Layout, |
| const MCFixup *Fixup) const { |
| if (Kind == VK_RISCV_PCREL_LO && evaluatePCRelLo(Res, Layout, Fixup)) |
| return true; |
| |
| if (!getSubExpr()->evaluateAsRelocatable(Res, Layout, Fixup)) |
| return false; |
| |
| // Some custom fixup types are not valid with symbol difference expressions |
| if (Res.getSymA() && Res.getSymB()) { |
| switch (getKind()) { |
| default: |
| return true; |
| case VK_RISCV_LO: |
| case VK_RISCV_HI: |
| case VK_RISCV_PCREL_LO: |
| case VK_RISCV_PCREL_HI: |
| case VK_RISCV_GOT_HI: |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| void RISCVMCExpr::visitUsedExpr(MCStreamer &Streamer) const { |
| Streamer.visitUsedExpr(*getSubExpr()); |
| } |
| |
| RISCVMCExpr::VariantKind RISCVMCExpr::getVariantKindForName(StringRef name) { |
| return StringSwitch<RISCVMCExpr::VariantKind>(name) |
| .Case("lo", VK_RISCV_LO) |
| .Case("hi", VK_RISCV_HI) |
| .Case("pcrel_lo", VK_RISCV_PCREL_LO) |
| .Case("pcrel_hi", VK_RISCV_PCREL_HI) |
| .Case("got_pcrel_hi", VK_RISCV_GOT_HI) |
| .Default(VK_RISCV_Invalid); |
| } |
| |
| StringRef RISCVMCExpr::getVariantKindName(VariantKind Kind) { |
| switch (Kind) { |
| default: |
| llvm_unreachable("Invalid ELF symbol kind"); |
| case VK_RISCV_LO: |
| return "lo"; |
| case VK_RISCV_HI: |
| return "hi"; |
| case VK_RISCV_PCREL_LO: |
| return "pcrel_lo"; |
| case VK_RISCV_PCREL_HI: |
| return "pcrel_hi"; |
| case VK_RISCV_GOT_HI: |
| return "got_pcrel_hi"; |
| } |
| } |
| |
| bool RISCVMCExpr::evaluateAsConstant(int64_t &Res) const { |
| MCValue Value; |
| |
| if (Kind == VK_RISCV_PCREL_HI || Kind == VK_RISCV_PCREL_LO || |
| Kind == VK_RISCV_GOT_HI || Kind == VK_RISCV_CALL) |
| return false; |
| |
| if (!getSubExpr()->evaluateAsRelocatable(Value, nullptr, nullptr)) |
| return false; |
| |
| if (!Value.isAbsolute()) |
| return false; |
| |
| Res = evaluateAsInt64(Value.getConstant()); |
| return true; |
| } |
| |
| int64_t RISCVMCExpr::evaluateAsInt64(int64_t Value) const { |
| switch (Kind) { |
| default: |
| llvm_unreachable("Invalid kind"); |
| case VK_RISCV_LO: |
| return SignExtend64<12>(Value); |
| case VK_RISCV_HI: |
| // Add 1 if bit 11 is 1, to compensate for low 12 bits being negative. |
| return ((Value + 0x800) >> 12) & 0xfffff; |
| } |
| } |