[PATCH] D67122: [UBSan][clang][compiler-rt] Applying non-zero offset to nullptr is undefined behaviour

[Roman Lebedev via Phabricator via cfe-commits]

lebedev.ri marked an inline comment as done.
lebedev.ri added inline comments.


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Comment at: clang/lib/CodeGen/CGExprScalar.cpp:4703-4720
+    // 2) The sign of the difference between the computed address and the base
+    // pointer matches the sign of the total offset.
+    llvm::Value *ValidGEP;
+    auto *NoOffsetOverflow = Builder.CreateNot(OffsetOverflows);
+    if (SignedIndices) {
+      auto *PosOrZeroValid = Builder.CreateICmpUGE(ComputedGEP, IntPtr);
+      auto *PosOrZeroOffset = Builder.CreateICmpSGE(TotalOffset, Zero);
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This makes me ick every time i look at it.
I wonder if this can be sanely rewritten via `.with.overflow` intrinsic..


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D67122/new/

https://reviews.llvm.org/D67122