| //===---- i386.cpp - Generic JITLink i386 edge kinds, utilities -----===// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // Generic utilities for graphs representing i386 objects. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/ExecutionEngine/JITLink/i386.h" |
| |
| #define DEBUG_TYPE "jitlink" |
| |
| namespace llvm::jitlink::i386 { |
| |
| const char *getEdgeKindName(Edge::Kind K) { |
| switch (K) { |
| case None: |
| return "None"; |
| case Pointer32: |
| return "Pointer32"; |
| case PCRel32: |
| return "PCRel32"; |
| case Pointer16: |
| return "Pointer16"; |
| case PCRel16: |
| return "PCRel16"; |
| case Delta32: |
| return "Delta32"; |
| case Delta32FromGOT: |
| return "Delta32FromGOT"; |
| case RequestGOTAndTransformToDelta32FromGOT: |
| return "RequestGOTAndTransformToDelta32FromGOT"; |
| case BranchPCRel32: |
| return "BranchPCRel32"; |
| case BranchPCRel32ToPtrJumpStub: |
| return "BranchPCRel32ToPtrJumpStub"; |
| case BranchPCRel32ToPtrJumpStubBypassable: |
| return "BranchPCRel32ToPtrJumpStubBypassable"; |
| } |
| |
| return getGenericEdgeKindName(K); |
| } |
| |
| const char NullPointerContent[PointerSize] = {0x00, 0x00, 0x00, 0x00}; |
| |
| const char PointerJumpStubContent[6] = { |
| static_cast<char>(0xFFu), 0x25, 0x00, 0x00, 0x00, 0x00}; |
| |
| Error optimizeGOTAndStubAccesses(LinkGraph &G) { |
| LLVM_DEBUG(dbgs() << "Optimizing GOT entries and stubs:\n"); |
| |
| for (auto *B : G.blocks()) |
| for (auto &E : B->edges()) { |
| if (E.getKind() == i386::BranchPCRel32ToPtrJumpStubBypassable) { |
| auto &StubBlock = E.getTarget().getBlock(); |
| assert(StubBlock.getSize() == sizeof(PointerJumpStubContent) && |
| "Stub block should be stub sized"); |
| assert(StubBlock.edges_size() == 1 && |
| "Stub block should only have one outgoing edge"); |
| |
| auto &GOTBlock = StubBlock.edges().begin()->getTarget().getBlock(); |
| assert(GOTBlock.getSize() == G.getPointerSize() && |
| "GOT block should be pointer sized"); |
| assert(GOTBlock.edges_size() == 1 && |
| "GOT block should only have one outgoing edge"); |
| |
| auto &GOTTarget = GOTBlock.edges().begin()->getTarget(); |
| orc::ExecutorAddr EdgeAddr = B->getAddress() + E.getOffset(); |
| orc::ExecutorAddr TargetAddr = GOTTarget.getAddress(); |
| |
| int64_t Displacement = TargetAddr - EdgeAddr + 4; |
| if (isInt<32>(Displacement)) { |
| E.setKind(i386::BranchPCRel32); |
| E.setTarget(GOTTarget); |
| LLVM_DEBUG({ |
| dbgs() << " Replaced stub branch with direct branch:\n "; |
| printEdge(dbgs(), *B, E, getEdgeKindName(E.getKind())); |
| dbgs() << "\n"; |
| }); |
| } |
| } |
| } |
| |
| return Error::success(); |
| } |
| |
| } // namespace llvm::jitlink::i386 |