041b0a81b0
# summary This MR fix `isBeforeInBlock` crash bug mentioned in https://github.com/llvm/llvm-project/issues/60909. Fixes #60909. # Trigger condition 1. A block only have one operation. 2. `block->isOpOrderValid()` is true, but `op->hasValidOrder()` is false. 3. call: `op->isBeforeInBlock(op)`, compared with op itself. Will crash on `assert(blockFront != blockBack && "expected more than one operation");` # Case study Simplified repro case in `mlir/test/Pass/scf2cf-print-liveness-crash.mlir` When put `-convert-scf-to-cf -test-print-liveness` together in one cmd line, the first pass will work normally and crash on the second pass. Details please refer https://github.com/llvm/llvm-project/issues/60909 # Solutions option1. in `isBeforeInBlock`, check if block only have one operation before step into `updateOrderIfNecessary`, if have only one, it must return false option2. in `isBeforeInBlock`, check if `this == other`, if true return false option3. fix `addNodeToList` logic I prefer option3: When a block contains only one operation and the user calls op->isBeforeInBlock(op), if block->isOpOrderValid() returns true, updateOrderIfNecessary is called. If op->hasValidOrder() is false, it will crash at the assertion assert(blockFront != blockBack && "expected more than one operation");. This behavior is abnormal and needs fixing. I discovered that after the first pass of `-convert-scf-to-cf`, there is a block with only one operation where the block order is valid but the operation order is invalid, leading to a crash when `-test-print-liveness` pass runs. --------- Co-authored-by: isaacw <isaacw@nvidia.com>
52 KiB
52 KiB