[llvm] Introduce callee_type metadata

Introduce `callee_type` metadata which will be attached to the indirect
call instructions.

The `callee_type` metadata will be used to generate `.callgraph` section
described in this RFC:
https://lists.llvm.org/pipermail/llvm-dev/2021-July/151739.html

Reviewers: morehouse, petrhosek, nikic, ilovepi

Reviewed By: nikic, ilovepi

Pull Request: https://github.com/llvm/llvm-project/pull/87573

1 files changed, 31 insertions, 0 deletions

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 8c8ed3c..9bd573e 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -531,6 +531,7 @@ private:
   void visitCallStackMetadata(MDNode *MD);
   void visitMemProfMetadata(Instruction &I, MDNode *MD);
   void visitCallsiteMetadata(Instruction &I, MDNode *MD);
+  void visitCalleeTypeMetadata(Instruction &I, MDNode *MD);
   void visitDIAssignIDMetadata(Instruction &I, MDNode *MD);
   void visitMMRAMetadata(Instruction &I, MDNode *MD);
   void visitAnnotationMetadata(MDNode *Annotation);
@@ -5193,6 +5194,33 @@ void Verifier::visitCallsiteMetadata(Instruction &I, MDNode *MD) {
   visitCallStackMetadata(MD);
 }
 
+static inline bool isConstantIntMetadataOperand(const Metadata *MD) {
+  if (auto *VAL = dyn_cast<ValueAsMetadata>(MD))
+    return isa<ConstantInt>(VAL->getValue());
+  return false;
+}
+
+void Verifier::visitCalleeTypeMetadata(Instruction &I, MDNode *MD) {
+  Check(isa<CallBase>(I), "!callee_type metadata should only exist on calls",
+        &I);
+  for (Metadata *Op : MD->operands()) {
+    Check(isa<MDNode>(Op),
+          "The callee_type metadata must be a list of type metadata nodes", Op);
+    auto *TypeMD = cast<MDNode>(Op);
+    Check(TypeMD->getNumOperands() == 2,
+          "Well-formed generalized type metadata must contain exactly two "
+          "operands",
+          Op);
+    Check(isConstantIntMetadataOperand(TypeMD->getOperand(0)) &&
+              mdconst::extract<ConstantInt>(TypeMD->getOperand(0))->isZero(),
+          "The first operand of type metadata for functions must be zero", Op);
+    Check(TypeMD->hasGeneralizedMDString(),
+          "Only generalized type metadata can be part of the callee_type "
+          "metadata list",
+          Op);
+  }
+}
+
 void Verifier::visitAnnotationMetadata(MDNode *Annotation) {
   Check(isa<MDTuple>(Annotation), "annotation must be a tuple");
   Check(Annotation->getNumOperands() >= 1,
@@ -5470,6 +5498,9 @@ void Verifier::visitInstruction(Instruction &I) {
   if (MDNode *MD = I.getMetadata(LLVMContext::MD_callsite))
     visitCallsiteMetadata(I, MD);
 
+  if (MDNode *MD = I.getMetadata(LLVMContext::MD_callee_type))
+    visitCalleeTypeMetadata(I, MD);
+
   if (MDNode *MD = I.getMetadata(LLVMContext::MD_DIAssignID))
     visitDIAssignIDMetadata(I, MD);