Change ELFCodeEmitter logic to emit the constant pool and jump tables to
their appropriate sections before the code itself. They need to be emitted
before the function because on some targets (x86 but not x86_64) the later
may reference a JT or CP entry address
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76672 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ELFCodeEmitter.cpp b/lib/CodeGen/ELFCodeEmitter.cpp
index c77334a..fb439c6 100644
--- a/lib/CodeGen/ELFCodeEmitter.cpp
+++ b/lib/CodeGen/ELFCodeEmitter.cpp
@@ -54,6 +54,12 @@
// Record the function start offset
FnStartOff = ES->getCurrentPCOffset();
+
+ // Emit constant pool and jump tables to their appropriate sections.
+ // They need to be emitted before the function because in some targets
+ // the later may reference JT or CP entry address.
+ emitConstantPool(MF.getConstantPool());
+ emitJumpTables(MF.getJumpTableInfo());
}
/// finishFunction - This callback is invoked after the function is completely
@@ -78,11 +84,17 @@
if (!F->hasPrivateLinkage())
EW.SymbolList.push_back(FnSym);
- // Emit constant pool to appropriate section(s)
- emitConstantPool(MF.getConstantPool());
-
- // Emit jump tables to appropriate section
- emitJumpTables(MF.getJumpTableInfo());
+ // Patch up Jump Table Section relocations to use the real MBBs offsets
+ // now that the MBB label offsets inside the function are known.
+ ELFSection &JTSection = EW.getJumpTableSection();
+ for (std::vector<MachineRelocation>::iterator MRI = JTRelocations.begin(),
+ MRE = JTRelocations.end(); MRI != MRE; ++MRI) {
+ MachineRelocation &MR = *MRI;
+ unsigned MBBOffset = getMachineBasicBlockAddress(MR.getBasicBlock());
+ MR.setResultPointer((void*)MBBOffset);
+ MR.setConstantVal(ES->SectionIdx);
+ JTSection.addRelocation(MR);
+ }
// Relocations
// -----------
@@ -105,7 +117,7 @@
MR.setResultPointer((void*)Addr);
} else if (MR.isJumpTableIndex()) {
Addr = getJumpTableEntryAddress(MR.getJumpTableIndex());
- MR.setConstantVal(JumpTableSectionIdx);
+ MR.setConstantVal(JTSection.SectionIdx);
MR.setResultPointer((void*)Addr);
} else {
llvm_unreachable("Unhandled relocation type");
@@ -114,6 +126,7 @@
}
// Clear per-function data structures.
+ JTRelocations.clear();
Relocations.clear();
CPLocations.clear();
CPSections.clear();
@@ -159,21 +172,15 @@
"PIC codegen not yet handled for elf jump tables!");
const TargetELFWriterInfo *TEW = TM.getELFWriterInfo();
+ unsigned EntrySize = MJTI->getEntrySize();
// Get the ELF Section to emit the jump table
ELFSection &JTSection = EW.getJumpTableSection();
- JumpTableSectionIdx = JTSection.SectionIdx;
-
- // Entries in the JT Section are relocated against the text section
- ELFSection &TextSection = EW.getTextSection();
// For each JT, record its offset from the start of the section
for (unsigned i = 0, e = JT.size(); i != e; ++i) {
const std::vector<MachineBasicBlock*> &MBBs = JT[i].MBBs;
- DOUT << "JTSection.size(): " << JTSection.size() << "\n";
- DOUT << "JTLocations.size: " << JTLocations.size() << "\n";
-
// Record JT 'i' offset in the JT section
JTLocations.push_back(JTSection.size());
@@ -182,19 +189,14 @@
for (unsigned mi = 0, me = MBBs.size(); mi != me; ++mi) {
unsigned MachineRelTy = TEW->getAbsoluteLabelMachineRelTy();
MachineRelocation MR =
- MachineRelocation::getBB(JTSection.size(),
- MachineRelTy,
- MBBs[mi]);
-
- // Offset of JT 'i' in JT section
- MR.setResultPointer((void*)getMachineBasicBlockAddress(MBBs[mi]));
- MR.setConstantVal(TextSection.SectionIdx);
+ MachineRelocation::getBB(JTSection.size(), MachineRelTy, MBBs[mi]);
// Add the relocation to the Jump Table section
- JTSection.addRelocation(MR);
+ JTRelocations.push_back(MR);
// Output placeholder for MBB in the JT section
- JTSection.emitWord(0);
+ for (unsigned s=0; s < EntrySize; ++s)
+ JTSection.emitByte(0);
}
}
}