[llvm] [Attributor] New attribute to identify what byte ranges are alive for an allocation (PR #66148)

[Johannes Doerfert via llvm-commits]

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@@ -12658,6 +12669,268 @@ struct AAAddressSpaceCallSiteArgument final : AAAddressSpaceImpl {
 };
 } // namespace
 
+/// ----------- Allocation Info ----------
+namespace {
+struct AAAllocationInfoImpl : public AAAllocationInfo {
+  AAAllocationInfoImpl(const IRPosition &IRP, Attributor &A)
+      : AAAllocationInfo(IRP, A) {}
+
+  std::optional<TypeSize> getAllocatedSize() const override {
+    assert(isValidState() && "the AA is invalid");
+    return AssumedAllocatedSize;
+  }
+
+  bool isaMallocInst(Instruction *I) {
+    CallInst *Call = dyn_cast<CallInst>(I);
+    auto CallName = Call->getCalledFunction()->getName();
+    if (CallName.str() == "malloc")
+      return true;
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jdoerfert wrote:

This is not how we test for malloc. Look at AAHeapToStack for an example on how to handle allocator functions. We might want to start with allocas only if it makes it simpler.

https://github.com/llvm/llvm-project/pull/66148