[Lldb-commits] [PATCH] D80955: Fix UB in EmulateInstructionARM64.cpp
Adrian Prantl via Phabricator via lldb-commits
lldb-commits at lists.llvm.org
Mon Jun 1 17:21:58 PDT 2020
aprantl marked an inline comment as done.
aprantl added inline comments.
Comment at: lldb/source/Plugins/Instruction/ARM64/EmulateInstructionARM64.cpp:99
+ if (!overflow)
+ overflow |= !llvm::checkedAdd(*signed_sum, SInt(carry_in));
uint64_t result = unsigned_sum;
> The docs  say 'integer signed_sum = SInt(x) + SInt(y) + UInt(carry_in)', but I bet checkedAdd doesn't support that, and anyway carry_in is 1-bit so it doesn't matter.
>  https://developer.arm.com/docs/ddi0596/e/shared-pseudocode-functions/shared-functionsinteger-pseudocode#impl-shared.AddWithCarry.3
Am I misreading this or are we also setting the C(arry) flag inverted according to the documentation?
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