lebedev.ri added a comment. In https://reviews.llvm.org/D48958#1160848, @vsk wrote:
> In https://reviews.llvm.org/D48958#1160494, @lebedev.ri wrote: > > > In https://reviews.llvm.org/D48958#1160479, @vsk wrote: > > > > > In https://reviews.llvm.org/D48958#1160435, @lebedev.ri wrote: > > > > > > > Thank you for taking a look! > > > > > > > > In https://reviews.llvm.org/D48958#1160381, @vsk wrote: > > > > > > > > > I have some minor comments but overall I think this is in good shape. > > > > > It would be great to see some compile-time numbers just to make sure > > > > > this is tractable. I'm pretty sure -fsanitize=null would fire more > > > > > often across a codebase than this check, so I don't anticipate a big > > > > > surprise here. > > > > > > > > > > > > Could you please clarify, which numbers are you looking for, > > > > specifically? > > > > The time it takes to build llvm stage2 with `-fsanitize=implicit-cast`? > > > > Or the time it takes to build llvm stage3 with compiler built with > > > > `-fsanitize=implicit-cast`? > > > > > > > > > I had in mind measuring the difference between -fsanitize=undefined and > > > -fsanitize=undefined,implicit-cast, with a stage2 compiler. I think that > > > captures the expected use case: existing ubsan users enabling this new > > > check. > > > > > > FWIW, i'm trying to look into optimizing these new IR patterns right now > > https://reviews.llvm.org/D49179 https://reviews.llvm.org/D49247. > > > > >> (The numbers won't be too representable, whole stage-1 takes ~40 minutes > > >> here...) > > > > > > Ah I see, I'll run a few builds and take a stab at it, then. > > > > Yes, please, thank you! > > > The stage2 build traps before it finishes: > > FAILED: lib/IR/AttributesCompatFunc.inc.tmp > cd /Users/vsk/src/builds/llvm.org-lldbsan-stage2-R/tools/clang/stage2-bins > && > /Users/vsk/src/builds/llvm.org-lldbsan-stage2-R/tools/clang/stage2-bins/bin/llvm-tblgen > -gen-attrs -I /Users/vsk/src/llvm.org-lldbsan/llvm/lib/IR -I > /Users/vsk/src/llvm.org-lldbsan/llvm/include > /Users/vsk/src/llvm.org-lldbsan/llvm/lib/IR/AttributesCompatFunc.td -o > lib/IR/AttributesCompatFunc.inc.tmp -d lib/IR/AttributesCompatFunc.inc.d > /Users/vsk/src/llvm.org-lldbsan/llvm/include/llvm/ADT/DenseMap.h:732:66: > runtime error: implicit cast from type 'uint64_t' (aka 'unsigned long long') > of value 4294967296 (64-bit, unsigned) to type 'unsigned int' changed the > value to 0 (32-bit, unsigned) > /bin/sh: line 1: 96848 Abort trap: 6 > > > This looks like a false positive to me. It's complaining about > `static_cast<unsigned>(NextPowerOf2(...))`, but the static_cast is explicit. Good to know, so the stack-based logic for `ExplicitCastExpr` detection needs further tests/refinements.. Repository: rC Clang https://reviews.llvm.org/D48958 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
