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[flang] Avoid double free in bufferize pass (#93922)

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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`.
This commit is contained in:
Valentin Clement (バレンタイン クレメン) 2024-05-31 08:23:27 -07:00 committed by GitHub
parent c5e417a812
commit e6bef08e22
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2 changed files with 33 additions and 0 deletions
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5
flang/lib/Optimizer/HLFIR/Transforms/BufferizeHLFIR.cpp
View File

@ -534,6 +534,11 @@ struct AssociateOpConversion
mlir::Value firBase = hlfir::Entity{bufferizedExpr}.getFirBase();
replaceWith(bufferizedExpr, firBase, mustFree);
eraseAllUsesInDestroys(associate.getSource(), rewriter);
// Make sure to erase the hlfir.destroy if there is an indirection through
// a hlfir.no_reassoc operation.
if (auto noReassoc = mlir::dyn_cast_or_null<hlfir::NoReassocOp>(
associate.getSource().getDefiningOp()))
eraseAllUsesInDestroys(noReassoc.getVal(), rewriter);
return mlir::success();
}
if (isTrivialValue) {

28
flang/test/HLFIR/bufferize01.fir
View File

@ -143,3 +143,31 @@ fir.global linkonce @_QQclXce30ef70ff16a711a97719fb946c0b3d constant : !fir.char
fir.has_value %0 : !fir.char<1,1>
}
func.func private @_FortranAPushArrayConstructorValue(!fir.llvm_ptr<i8>, !fir.box<none>) -> none attributes {fir.runtime}
// -----
// Test that only a single freemem is generated.
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>)
// CHECK-LABEL: func.func @double_free(
// CHECK-SAME: %[[ARG0:.*]]: !fir.boxchar<1>) {
// CHECK: %[[NO_REASSOC:.*]] = hlfir.no_reassoc %[[ARG0]] : !fir.boxchar<1>
// CHECK: %[[BOX_ADDR:.*]] = fir.box_addr %[[NO_REASSOC]] : (!fir.boxchar<1>) -> !fir.ref<!fir.char<1,?>>
// CHECK: fir.call @noop
// CHECK: %[[CONV:.*]] = fir.convert %[[BOX_ADDR]] : (!fir.ref<!fir.char<1,?>>) -> !fir.heap<!fir.char<1,?>>
// CHECK: fir.freemem %[[CONV]] : !fir.heap<!fir.char<1,?>>
// CHECK-NOT: fir.freemem