ebevhan added inline comments.
================ Comment at: clang/lib/Sema/SemaChecking.cpp:13981 + bool overflow; + llvm::APInt product(index); + product += 1; ---------------- ebevhan wrote: > chrish_ericsson_atx wrote: > > ebevhan wrote: > > > What if index is wider than AddrBits, but the active bits are fewer? Then > > > you might miss out on triggering the overflow case in the multiplication. > > Line 13984 checks for active bits of product being less than AddrBits, > > which is the same case (since product, by definition, has same width as > > index). So I think this is covered. If I've misunderstood, please re-ping. > The overflow limit for _ovf is determined by the width of the APInt. If index > is 32 bits wide but only has 14 bits active, and AddrBits is 16, then an > umul_ovf might overflow past 16 bits but not for 32 bits since the product is > the same width as the index. Then we won't detect the overflow. Scratch this; I missed the second getActiveBits check. With that it should be fine. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D86796/new/ https://reviews.llvm.org/D86796 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
