[LV] Crash in VPPartialReductionRecipe::computeCost #162902
Description
Compiling this:
char a, b; char *c; void d(bool e) { for (;;) for (int f; f < 2; f += e) { a = c[f]; b += !f ?: e; } } with clang -O2 -mcpu=grace results in a crash with this backtrace:
#4 0x0000000005837d75 llvm::VPPartialReductionRecipe::computeCost(llvm::ElementCount, llvm::VPCostContext&) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5837d75) #5 0x0000000005841f46 llvm::VPRecipeBase::cost(llvm::ElementCount, llvm::VPCostContext&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5841f46) #6 0x0000000005807b57 llvm::VPBasicBlock::cost(llvm::ElementCount, llvm::VPCostContext&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5807b57) #7 0x000000000580e888 llvm::VPRegionBlock::cost(llvm::ElementCount, llvm::VPCostContext&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x580e888) #8 0x000000000580f70d llvm::VPlan::cost(llvm::ElementCount, llvm::VPCostContext&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x580f70d) #9 0x00000000056bdbda llvm::LoopVectorizationPlanner::cost(llvm::VPlan&, llvm::ElementCount) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x56bdbda) #10 0x00000000056c443a llvm::LoopVectorizationPlanner::computeBestVF() (.part.0) LoopVectorize.cpp:0:0 #11 0x00000000056c537a llvm::LoopVectorizationPlanner::computeBestVF() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x56c537a) #12 0x00000000056ccee7 llvm::LoopVectorizePass::processLoop(llvm::Loop*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x56ccee7) See also: https://godbolt.org/z/njcnr58a4