213709e7be
In getNVPTXLaneID(CodeGenFunction &), the value of LaneIDBits is 4294967295 since function call llvm::Log2_32(CGF->getTarget()->getGridValue().GV_Warp_Size) might return 4294967295.
unsigned LaneIDBits =
llvm::Log2_32(CGF.getTarget().getGridValue().GV_Warp_Size);
unsigned LaneIDMask = ~0u >> (32u - LaneIDBits);
The shift amount (32U - LaneIDBits) might be 33, So it has undefined behavior for right shifting by more than 31 bits.
This patch adds an assert to guard the LaneIDBits overflow issue with LaneIDMask value.
Reviewed By: tahonermann
Differential Revision: https://reviews.llvm.org/D151606
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