Merge rust-lang#47

47: Make it so we can read the `.llvm_bb_addr_map` section from memory at runtime r=ltratt a=vext01 Co-authored-by: Edd Barrett <vext01@gmail.com>
vext01 · Sep 29, 2022 · bd1d951 · bd1d951
2 parents 1cb9a4a + 3c763c9
commit bd1d951
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Showing 3 changed files with 37 additions and 0 deletions.
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -133,6 +133,8 @@ static cl::opt<bool>
                       cl::desc("Embed final IR as bitcode after all "
                                "optimisations and transformations have run."));
 
+extern bool YkAllocLLVMBBAddrMapSection;
+
 const char DWARFGroupName[] = "dwarf";
 const char DWARFGroupDescription[] = "DWARF Emission";
 const char DbgTimerName[] = "emit";
@@ -1324,6 +1326,20 @@ static unsigned getBBAddrMapMetadata(const MachineBasicBlock &MBB) {
          (const_cast<MachineBasicBlock &>(MBB).canFallThrough() << 3);
 }
 
+void emitYkBBAddrMapSymbol(const MachineFunction &MF, MCStreamer &OutStreamer,
+                           bool Start) {
+  std::string SymName("ykllvm.bbaddrmap.");
+  SymName.append(MF.getName().str());
+  if (Start)
+    SymName.append(".start");
+  else
+    SymName.append(".end");
+
+  MCSymbol *Sym = MF.getContext().getOrCreateSymbol(SymName);
+  OutStreamer.emitSymbolAttribute(Sym, llvm::MCSA_Global);
+  OutStreamer.emitLabel(Sym);
+}
+
 void AsmPrinter::emitBBAddrMapSection(const MachineFunction &MF) {
   MCSection *BBAddrMapSection =
       getObjFileLowering().getBBAddrMapSection(*MF.getSection());
@@ -1333,6 +1349,11 @@ void AsmPrinter::emitBBAddrMapSection(const MachineFunction &MF) {
 
   OutStreamer->pushSection();
   OutStreamer->switchSection(BBAddrMapSection);
+
+  // Add the `ykllvm.bbaddrmap.<func>.start` symbol.
+  if (YkAllocLLVMBBAddrMapSection)
+    emitYkBBAddrMapSymbol(MF, *OutStreamer, true);
+
   OutStreamer->AddComment("version");
   OutStreamer->emitInt8(OutStreamer->getContext().getBBAddrMapVersion());
   OutStreamer->AddComment("feature");
@@ -1421,6 +1442,11 @@ void AsmPrinter::emitBBAddrMapSection(const MachineFunction &MF) {
       OutStreamer->emitULEB128IntValue(I);
     }
   }
+
+  // Add the `ykllvm.bbaddrmap.<func>.end` symbol.
+  if (YkAllocLLVMBBAddrMapSection)
+    emitYkBBAddrMapSymbol(MF, *OutStreamer, false);
+
   OutStreamer->popSection();
 }
 

diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -1120,6 +1120,8 @@ MCObjectFileInfo::getStackSizesSection(const MCSection &TextSec) const {
                             cast<MCSymbolELF>(TextSec.getBeginSymbol()));
 }
 
+extern bool YkAllocLLVMBBAddrMapSection;
+
 MCSection *
 MCObjectFileInfo::getBBAddrMapSection(const MCSection &TextSec) const {
   if (Ctx->getObjectFileType() != MCContext::IsELF)
@@ -1133,6 +1135,9 @@ MCObjectFileInfo::getBBAddrMapSection(const MCSection &TextSec) const {
     Flags |= ELF::SHF_GROUP;
   }
 
+  if (YkAllocLLVMBBAddrMapSection)
+    Flags |= ELF::SHF_ALLOC;
+
   // Use the text section's begin symbol and unique ID to create a separate
   // .llvm_bb_addr_map section associated with every unique text section.
   return Ctx->getELFSection(".llvm_bb_addr_map", ELF::SHT_LLVM_BB_ADDR_MAP,

diff --git a/llvm/lib/Support/Yk.cpp b/llvm/lib/Support/Yk.cpp
@@ -6,3 +6,9 @@ bool YkAllocLLVMBCSection;
 static cl::opt<bool, true> YkAllocLLVMBCSectionParser(
     "yk-alloc-llvmbc-section", cl::desc("Make the `.llvmbc` section loadable"),
     cl::NotHidden, cl::location(YkAllocLLVMBCSection));
+
+bool YkAllocLLVMBBAddrMapSection;
+static cl::opt<bool, true> YkAllocLLVMBBAddrMapSectionParser(
+    "yk-alloc-llvmbbaddrmap-section",
+    cl::desc("Make the `.llvmbbaddrmap` section loadable"), cl::NotHidden,
+    cl::location(YkAllocLLVMBBAddrMapSection));