================
@@ -12,27 +12,78 @@
#ifndef LLVM_ANALYSIS_INDIRECTCALLVISITOR_H
#define LLVM_ANALYSIS_INDIRECTCALLVISITOR_H
+#include "llvm/ADT/SetVector.h"
#include "llvm/IR/InstVisitor.h"
#include <vector>
namespace llvm {
-// Visitor class that finds all indirect call.
+// Visitor class that finds indirect calls or instructions that gives vtable
+// value, depending on Type.
struct PGOIndirectCallVisitor : public InstVisitor<PGOIndirectCallVisitor> {
+ enum class InstructionType {
+ kIndirectCall = 0,
+ kVTableVal = 1,
+ };
std::vector<CallBase *> IndirectCalls;
- PGOIndirectCallVisitor() = default;
+ std::vector<Instruction *> ProfiledAddresses;
+ PGOIndirectCallVisitor(InstructionType Type) : Type(Type) {}
void visitCallBase(CallBase &Call) {
- if (Call.isIndirectCall())
+ if (Call.isIndirectCall()) {
IndirectCalls.push_back(&Call);
+
+ if (Type != InstructionType::kVTableVal)
+ return;
+
+ LoadInst *LI = dyn_cast<LoadInst>(Call.getCalledOperand());
+ // The code pattern to look for
+ //
+ // %vtable = load ptr, ptr %b
+ // %vfn = getelementptr inbounds ptr, ptr %vtable, i64 1
+ // %2 = load ptr, ptr %vfn
+ // %call = tail call i32 %2(ptr %b)
+ //
+ // %vtable is the vtable address value to profile, and
+ // %2 is the indirect call target address to profile.
+ if (LI != nullptr) {
+ Value *Ptr = LI->getPointerOperand();
+ Value *VTablePtr = Ptr->stripInBoundsConstantOffsets();
+ // This is a heuristic to find address feeding instructions.
+ // FIXME: Add support in the frontend so LLVM type intrinsics are
+ // emitted without LTO. This way, added intrinsics could filter
+ // non-vtable instructions and reduce instrumentation overhead.
+ // Since a non-vtable profiled address is not within the address
+ // range of vtable objects, it's stored as zero in indexed profiles.
----------------
snehasish wrote:
Can we drop the ones that don't belong to a vtable add range during merge
instead of storing zero?
https://github.com/llvm/llvm-project/pull/66825
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