[llvm][AsmPrinter] Emit call graph section

Collect the necessary information for constructing the call graph
section, and emit to .callgraph section of the binary.

MD5 hash of the callee_type metadata string is used as the numerical
type id emitted.

Reviewers: ilovepi

Reviewed By: ilovepi

Pull Request: https://github.com/llvm/llvm-project/pull/87576

1 files changed, 20 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index 0069d12..393eed1 100644
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -537,6 +537,8 @@ void MCObjectFileInfo::initELFMCObjectFileInfo(const Triple &T, bool Large) {
   EHFrameSection =
       Ctx->getELFSection(".eh_frame", EHSectionType, EHSectionFlags);
 
+  CallGraphSection = Ctx->getELFSection(".callgraph", ELF::SHT_PROGBITS, 0);
+
   StackSizesSection = Ctx->getELFSection(".stack_sizes", ELF::SHT_PROGBITS, 0);
 
   PseudoProbeSection = Ctx->getELFSection(".pseudo_probe", DebugSecType, 0);
@@ -1121,6 +1123,24 @@ MCSection *MCObjectFileInfo::getDwarfComdatSection(const char *Name,
 }
 
 MCSection *
+MCObjectFileInfo::getCallGraphSection(const MCSection &TextSec) const {
+  if (Ctx->getObjectFileType() != MCContext::IsELF)
+    return CallGraphSection;
+
+  const MCSectionELF &ElfSec = static_cast<const MCSectionELF &>(TextSec);
+  unsigned Flags = ELF::SHF_LINK_ORDER;
+  StringRef GroupName;
+  if (const MCSymbol *Group = ElfSec.getGroup()) {
+    GroupName = Group->getName();
+    Flags |= ELF::SHF_GROUP;
+  }
+
+  return Ctx->getELFSection(".callgraph", ELF::SHT_PROGBITS, Flags, 0,
+                            GroupName, true, ElfSec.getUniqueID(),
+                            cast<MCSymbolELF>(TextSec.getBeginSymbol()));
+}
+
+MCSection *
 MCObjectFileInfo::getStackSizesSection(const MCSection &TextSec) const {
   if ((Ctx->getObjectFileType() != MCContext::IsELF) ||
       Ctx->getTargetTriple().isPS4())