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

[Shilei Tian via llvm-commits]

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@@ -12672,6 +12678,236 @@ 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;
+  }
+
+  std::optional<TypeSize> findInitialAllocationSize(Instruction *I,
+                                                    const DataLayout &DL) {
+
+    // TODO: implement case for malloc like instructions
+    switch (I->getOpcode()) {
+    case Instruction::Alloca: {
+      AllocaInst *AI = cast<AllocaInst>(I);
+      return AI->getAllocationSize(DL);
+      break;
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shiltian wrote:

No need to have a break here

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