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AArch64: add stubs to support long function calls on MCJIT
As with global accesses, external functions could exist anywhere in memory. Therefore the stub must create a complete 64-bit address. This patch implements the fragment as (roughly): movz x16, #:abs_g3:somefunc movk x16, #:abs_g2_nc:somefunc movk x16, #:abs_g1_nc:somefunc movk x16, #:abs_g0_nc:somefunc br x16 In principle we could save 4 bytes by using a literal-load instead, but it is unclear that would be more efficient and can only be tested when real hardware is readily available. This allows (for example) the MCJIT test 2003-05-07-ArgumentTest to pass on AArch64. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181133 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -336,7 +336,25 @@ void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
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}
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uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
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if (Arch == Triple::arm) {
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if (Arch == Triple::aarch64) {
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// This stub has to be able to access the full address space,
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// since symbol lookup won't necessarily find a handy, in-range,
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// PLT stub for functions which could be anywhere.
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uint32_t *StubAddr = (uint32_t*)Addr;
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// Stub can use ip0 (== x16) to calculate address
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*StubAddr = 0xd2e00010; // movz ip0, #:abs_g3:<addr>
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StubAddr++;
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*StubAddr = 0xf2c00010; // movk ip0, #:abs_g2_nc:<addr>
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StubAddr++;
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*StubAddr = 0xf2a00010; // movk ip0, #:abs_g1_nc:<addr>
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StubAddr++;
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*StubAddr = 0xf2800010; // movk ip0, #:abs_g0_nc:<addr>
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StubAddr++;
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*StubAddr = 0xd61f0200; // br ip0
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return Addr;
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} else if (Arch == Triple::arm) {
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// TODO: There is only ARM far stub now. We should add the Thumb stub,
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// and stubs for branches Thumb - ARM and ARM - Thumb.
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uint32_t *StubAddr = (uint32_t*)Addr;
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@ -296,6 +296,19 @@ void RuntimeDyldELF::resolveAArch64Relocation(const SectionEntry &Section,
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*TargetPtr = static_cast<uint32_t>(Result & 0xffffffffU);
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break;
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}
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case ELF::R_AARCH64_CALL26: // fallthrough
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case ELF::R_AARCH64_JUMP26: {
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// Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the
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// calculation.
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uint64_t BranchImm = Value + Addend - FinalAddress;
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// "Check that -2^27 <= result < 2^27".
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assert(-(1LL << 27) <= static_cast<int64_t>(BranchImm) &&
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static_cast<int64_t>(BranchImm) < (1LL << 27));
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// Immediate goes in bits 25:0 of B and BL.
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*TargetPtr |= static_cast<uint32_t>(BranchImm & 0xffffffcU) >> 2;
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break;
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}
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case ELF::R_AARCH64_MOVW_UABS_G3: {
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uint64_t Result = Value + Addend;
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// Immediate goes in bits 20:5 of MOVZ/MOVK instruction
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@ -775,7 +788,56 @@ void RuntimeDyldELF::processRelocationRef(unsigned SectionID,
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DEBUG(dbgs() << "\t\tSectionID: " << SectionID
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<< " Offset: " << Offset
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<< "\n");
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if (Arch == Triple::arm &&
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if (Arch == Triple::aarch64 &&
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(RelType == ELF::R_AARCH64_CALL26 ||
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RelType == ELF::R_AARCH64_JUMP26)) {
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// This is an AArch64 branch relocation, need to use a stub function.
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DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
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SectionEntry &Section = Sections[SectionID];
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// Look for an existing stub.
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StubMap::const_iterator i = Stubs.find(Value);
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if (i != Stubs.end()) {
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resolveRelocation(Section, Offset,
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(uint64_t)Section.Address + i->second, RelType, 0);
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DEBUG(dbgs() << " Stub function found\n");
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} else {
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// Create a new stub function.
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DEBUG(dbgs() << " Create a new stub function\n");
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Stubs[Value] = Section.StubOffset;
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uint8_t *StubTargetAddr = createStubFunction(Section.Address +
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Section.StubOffset);
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RelocationEntry REmovz_g3(SectionID,
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StubTargetAddr - Section.Address,
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ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
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RelocationEntry REmovk_g2(SectionID,
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StubTargetAddr - Section.Address + 4,
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ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
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RelocationEntry REmovk_g1(SectionID,
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StubTargetAddr - Section.Address + 8,
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ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
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RelocationEntry REmovk_g0(SectionID,
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StubTargetAddr - Section.Address + 12,
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ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
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if (Value.SymbolName) {
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addRelocationForSymbol(REmovz_g3, Value.SymbolName);
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addRelocationForSymbol(REmovk_g2, Value.SymbolName);
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addRelocationForSymbol(REmovk_g1, Value.SymbolName);
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addRelocationForSymbol(REmovk_g0, Value.SymbolName);
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} else {
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addRelocationForSection(REmovz_g3, Value.SectionID);
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addRelocationForSection(REmovk_g2, Value.SectionID);
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addRelocationForSection(REmovk_g1, Value.SectionID);
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addRelocationForSection(REmovk_g0, Value.SectionID);
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}
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resolveRelocation(Section, Offset,
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(uint64_t)Section.Address + Section.StubOffset,
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RelType, 0);
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Section.StubOffset += getMaxStubSize();
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}
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} else if (Arch == Triple::arm &&
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(RelType == ELF::R_ARM_PC24 ||
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RelType == ELF::R_ARM_CALL ||
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RelType == ELF::R_ARM_JUMP24)) {
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@ -166,6 +166,8 @@ protected:
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Triple::ArchType Arch;
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inline unsigned getMaxStubSize() {
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if (Arch == Triple::aarch64)
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return 20; // movz; movk; movk; movk; br
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if (Arch == Triple::arm || Arch == Triple::thumb)
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return 8; // 32-bit instruction and 32-bit address
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else if (Arch == Triple::mipsel || Arch == Triple::mips)
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