[llvm] r181133 - AArch64: add stubs to support long function calls on MCJIT
Tim Northover
Tim.Northover at arm.com
Sat May 4 13:14:10 PDT 2013
Author: tnorthover
Date: Sat May 4 15:14:09 2013
New Revision: 181133
URL: http://llvm.org/viewvc/llvm-project?rev=181133&view=rev
Log:
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.
Modified:
llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp?rev=181133&r1=181132&r2=181133&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp (original)
+++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp Sat May 4 15:14:09 2013
@@ -336,7 +336,25 @@ void RuntimeDyldImpl::addRelocationForSy
}
uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
- if (Arch == Triple::arm) {
+ if (Arch == Triple::aarch64) {
+ // This stub has to be able to access the full address space,
+ // since symbol lookup won't necessarily find a handy, in-range,
+ // PLT stub for functions which could be anywhere.
+ uint32_t *StubAddr = (uint32_t*)Addr;
+
+ // Stub can use ip0 (== x16) to calculate address
+ *StubAddr = 0xd2e00010; // movz ip0, #:abs_g3:<addr>
+ StubAddr++;
+ *StubAddr = 0xf2c00010; // movk ip0, #:abs_g2_nc:<addr>
+ StubAddr++;
+ *StubAddr = 0xf2a00010; // movk ip0, #:abs_g1_nc:<addr>
+ StubAddr++;
+ *StubAddr = 0xf2800010; // movk ip0, #:abs_g0_nc:<addr>
+ StubAddr++;
+ *StubAddr = 0xd61f0200; // br ip0
+
+ return Addr;
+ } else if (Arch == Triple::arm) {
// TODO: There is only ARM far stub now. We should add the Thumb stub,
// and stubs for branches Thumb - ARM and ARM - Thumb.
uint32_t *StubAddr = (uint32_t*)Addr;
Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp?rev=181133&r1=181132&r2=181133&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp (original)
+++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp Sat May 4 15:14:09 2013
@@ -296,6 +296,19 @@ void RuntimeDyldELF::resolveAArch64Reloc
*TargetPtr = static_cast<uint32_t>(Result & 0xffffffffU);
break;
}
+ case ELF::R_AARCH64_CALL26: // fallthrough
+ case ELF::R_AARCH64_JUMP26: {
+ // Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the
+ // calculation.
+ uint64_t BranchImm = Value + Addend - FinalAddress;
+
+ // "Check that -2^27 <= result < 2^27".
+ assert(-(1LL << 27) <= static_cast<int64_t>(BranchImm) &&
+ static_cast<int64_t>(BranchImm) < (1LL << 27));
+ // Immediate goes in bits 25:0 of B and BL.
+ *TargetPtr |= static_cast<uint32_t>(BranchImm & 0xffffffcU) >> 2;
+ break;
+ }
case ELF::R_AARCH64_MOVW_UABS_G3: {
uint64_t Result = Value + Addend;
// Immediate goes in bits 20:5 of MOVZ/MOVK instruction
@@ -775,7 +788,56 @@ void RuntimeDyldELF::processRelocationRe
DEBUG(dbgs() << "\t\tSectionID: " << SectionID
<< " Offset: " << Offset
<< "\n");
- if (Arch == Triple::arm &&
+ if (Arch == Triple::aarch64 &&
+ (RelType == ELF::R_AARCH64_CALL26 ||
+ RelType == ELF::R_AARCH64_JUMP26)) {
+ // This is an AArch64 branch relocation, need to use a stub function.
+ DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
+ SectionEntry &Section = Sections[SectionID];
+
+ // Look for an existing stub.
+ StubMap::const_iterator i = Stubs.find(Value);
+ if (i != Stubs.end()) {
+ resolveRelocation(Section, Offset,
+ (uint64_t)Section.Address + i->second, RelType, 0);
+ DEBUG(dbgs() << " Stub function found\n");
+ } else {
+ // Create a new stub function.
+ DEBUG(dbgs() << " Create a new stub function\n");
+ Stubs[Value] = Section.StubOffset;
+ uint8_t *StubTargetAddr = createStubFunction(Section.Address +
+ Section.StubOffset);
+
+ RelocationEntry REmovz_g3(SectionID,
+ StubTargetAddr - Section.Address,
+ ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
+ RelocationEntry REmovk_g2(SectionID,
+ StubTargetAddr - Section.Address + 4,
+ ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
+ RelocationEntry REmovk_g1(SectionID,
+ StubTargetAddr - Section.Address + 8,
+ ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
+ RelocationEntry REmovk_g0(SectionID,
+ StubTargetAddr - Section.Address + 12,
+ ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
+
+ if (Value.SymbolName) {
+ addRelocationForSymbol(REmovz_g3, Value.SymbolName);
+ addRelocationForSymbol(REmovk_g2, Value.SymbolName);
+ addRelocationForSymbol(REmovk_g1, Value.SymbolName);
+ addRelocationForSymbol(REmovk_g0, Value.SymbolName);
+ } else {
+ addRelocationForSection(REmovz_g3, Value.SectionID);
+ addRelocationForSection(REmovk_g2, Value.SectionID);
+ addRelocationForSection(REmovk_g1, Value.SectionID);
+ addRelocationForSection(REmovk_g0, Value.SectionID);
+ }
+ resolveRelocation(Section, Offset,
+ (uint64_t)Section.Address + Section.StubOffset,
+ RelType, 0);
+ Section.StubOffset += getMaxStubSize();
+ }
+ } else if (Arch == Triple::arm &&
(RelType == ELF::R_ARM_PC24 ||
RelType == ELF::R_ARM_CALL ||
RelType == ELF::R_ARM_JUMP24)) {
Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h?rev=181133&r1=181132&r2=181133&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h (original)
+++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h Sat May 4 15:14:09 2013
@@ -166,6 +166,8 @@ protected:
Triple::ArchType Arch;
inline unsigned getMaxStubSize() {
+ if (Arch == Triple::aarch64)
+ return 20; // movz; movk; movk; movk; br
if (Arch == Triple::arm || Arch == Triple::thumb)
return 8; // 32-bit instruction and 32-bit address
else if (Arch == Triple::mipsel || Arch == Triple::mips)
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