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Fix MultiDefPrunedLiveness; add boundaries for dead end blocks. #62939

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Merged
merged 1 commit into from
Jan 10, 2023
Merged

Fix MultiDefPrunedLiveness; add boundaries for dead end blocks. #62939

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5 changes: 5 additions & 0 deletions lib/SIL/Utils/PrunedLiveness.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -578,6 +578,11 @@ void MultiDefPrunedLiveness::findBoundariesInBlock(
boundary.deadDefs.push_back(deadArg);
}
}
if (auto *predBB = block->getSinglePredecessorBlock()) {
if (getBlockLiveness(predBB) == PrunedLiveBlocks::LiveOut) {
boundary.boundaryEdges.push_back(block);
}
}
}
// All live-within blocks must contain a boundary.
assert(isLiveOut
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46 changes: 39 additions & 7 deletions test/SILOptimizer/ossa_lifetime_analysis.sil
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Expand Up @@ -176,7 +176,9 @@ bb0(%0 : @guaranteed $D):
return %99 : $()
}

// CHECK-LABEL: @testMultiDef
// A LiveOut block with a non-SSA def, bb0, has no liveness boundary.
//
// CHECK-LABEL: @testMultiDefLiveOutNoBoundary
// CHECK: MultiDef lifetime analysis:
// CHECK: def: [[CP0:%.*]] = copy_value %0 : $C
// CHECK: def: %{{.*}} = copy_value %0 : $C
Expand All @@ -187,12 +189,12 @@ bb0(%0 : @guaranteed $D):
// CHECK: bb3: LiveWithin,
// CHECK: bb4: LiveWithin,
// CHECK: bb1: LiveWithin,
// CHECK: lifetime-ending user: %{{.*}} = move_value [[CP0]] : $C
// CHECK: lifetime-ending user: destroy_value [[CP0]] : $C
// CHECK: lifetime-ending user: br bb4(%5 : $C)
// CHECK: lifetime-ending user: br bb4(%7 : $C)
// CHECK: lifetime-ending user: destroy_value %9 : $C
sil [ossa] @testMultiDef : $@convention(thin) (@guaranteed C) -> () {
// CHECK: last user: br bb4
// CHECK-NEXT: last user: br bb4
// CHECK-NEXT: last user: %{{.*}} = move_value [[CP0]] : $C
// CHECK-NEXT: last user: destroy_value %{{.*}} : $C
// CHECK-NEXT: last user: destroy_value [[CP0]] : $C
sil [ossa] @testMultiDefLiveOutNoBoundary : $@convention(thin) (@guaranteed C) -> () {
bb0(%0 : @guaranteed $C):
%copy0 = copy_value %0 : $C
debug_value [trace] %copy0 : $C
Expand All @@ -218,3 +220,33 @@ bb4(%phi : @owned $C):
%99 = tuple()
return %99 : $()
}

// A dead-end block with a def can still be a boundary edge. This can
// only happen in OSSA with incomplete lifetimes.
//
// CHECK-LABEL: @testMultiDefDeadDefBoundaryEdge
// CHECK: MultiDef lifetime analysis:
// CHECK: def: [[CP0:%.*]] = copy_value %0 : $C
// CHECK: def: [[CP3:%.*]] = copy_value %0 : $C
// CHECK: bb0: LiveOut,
// CHECK: bb1: LiveWithin,
// CHECK: bb2: LiveWithin,
// CHECK: last user: destroy_value [[CP0]] : $C
// CHECK-NEXT: boundary edge: bb1
// CHECK-NEXT: dead def: [[CP3]] = copy_value %0 : $C
sil [ossa] @testMultiDefDeadDefBoundaryEdge : $@convention(thin) (@guaranteed C) -> () {
bb0(%0 : @guaranteed $C):
%copy0 = copy_value %0 : $C
debug_value [trace] %copy0 : $C
cond_br undef, bb1, bb3

bb1:
%dead = copy_value %0 : $C
debug_value [trace] %dead : $C
unreachable

bb3:
destroy_value %copy0 : $C
%99 = tuple()
return %99 : $()
}