[all-commits] [llvm/llvm-project] e6bef0: [flang] Avoid double free in bufferize pass (#93922)

[Valentin Clement (バレンタイン クレメン) via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: e6bef08e22ac52aca0d6364f972cfb49c483adb3
      https://github.com/llvm/llvm-project/commit/e6bef08e22ac52aca0d6364f972cfb49c483adb3
  Author: Valentin Clement (バレンタイン クレメン) <clementval at gmail.com>
  Date:   2024-05-31 (Fri, 31 May 2024)

  Changed paths:
    M flang/lib/Optimizer/HLFIR/Transforms/BufferizeHLFIR.cpp
    M flang/test/HLFIR/bufferize01.fir

  Log Message:
  -----------
  [flang] Avoid double free in bufferize pass (#93922)

In some cases where we have an `hlfir.no_reassoc` operation, the
bufferization pass could not earse the hlfir.destroy op during the
`hlfir.associate` op conversion as show in the example below.

```
func.func @double_free(%arg0: !fir.boxchar<1>) {
  %c5 = arith.constant 5 : index
  %true = arith.constant true
  %0 = hlfir.as_expr %arg0 move %true : (!fir.boxchar<1>, i1) -> !hlfir.expr<!fir.char<1,?>>
  %1 = hlfir.no_reassoc %0 : !hlfir.expr<!fir.char<1,?>>
  %2:3 = hlfir.associate %1 typeparams %c5 {adapt.valuebyref} : (!hlfir.expr<!fir.char<1,?>>, index) -> (!fir.boxchar<1>, !fir.ref<!fir.char<1,?>>, i1)
  fir.call @noop(%2#0) : (!fir.boxchar<1>) -> ()
  hlfir.end_associate %2#1, %2#2 : !fir.ref<!fir.char<1,?>>, i1
  hlfir.destroy %0 : !hlfir.expr<!fir.char<1,?>>
  return
} 
func.func private @noop(!fir.boxchar<1>)
```

The bufferization pass is looking at uses of its source `%1` that is the
result of an `hlfir.no_reassoc` operation. In order to avoid double free
generation, also look at the indirection in presence of
`hlfir.no_reassoc`.



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