[all-commits] [llvm/llvm-project] 041b0a: [MLIR][Operation] Fix `isBeforeInBlock` crash bug ...

[wang-y-z via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 041b0a81b05cb20f0ece49bc72d3f6f611095ee0
      https://github.com/llvm/llvm-project/commit/041b0a81b05cb20f0ece49bc72d3f6f611095ee0
  Author: wang-y-z <57429717+wang-y-z at users.noreply.github.com>
  Date:   2024-09-21 (Sat, 21 Sep 2024)

  Changed paths:
    M mlir/lib/IR/Operation.cpp
    A mlir/test/Pass/scf-to-cf-and-print-liveness.mlir

  Log Message:
  -----------
  [MLIR][Operation] Fix `isBeforeInBlock` crash bug mentioned in https://github.com/llvm/llvm-project/issues/60909 (#101172)

# 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 at nvidia.com>



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