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[LVA] Don't invalidate reads/writes that don't alias any tracked values. #31136

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[LVA] Don't invalidate reads/writes that don't alias any tracked values. #31136

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[LVA] Don't invalidate reads/writes that don't alias any tracked values.
zoecarver Apr 19, 2020
ac2f96d
Merge branch 'master' into lva/dont-invalidate-no-alias
zoecarver May 10, 2020
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14 changes: 12 additions & 2 deletions lib/SILOptimizer/Transforms/DeadStoreElimination.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1089,7 +1089,12 @@ void DSEContext::processUnknownReadInstForGenKillSet(SILInstruction *I) {
for (unsigned i = 0; i < S->LocationNum; ++i) {
if (!S->BBMaxStoreSet.test(i))
continue;
if (!AA->mayReadFromMemory(I, LocationVault[i].getBase()))
auto val = LocationVault[i].getBase();
if (!AA->mayReadFromMemory(I, val))
continue;
if (llvm::all_of(I->getAllOperands(), [&AA = AA, &val](Operand &op) {
return AA->isNoAlias(op.get(), val);
}))
continue;
// Update the genset and kill set.
S->startTrackingLocation(S->BBKillSet, i);
Expand All @@ -1102,7 +1107,12 @@ void DSEContext::processUnknownReadInstForDSE(SILInstruction *I) {
for (unsigned i = 0; i < S->LocationNum; ++i) {
if (!S->isTrackingLocation(S->BBWriteSetMid, i))
continue;
if (!AA->mayReadFromMemory(I, LocationVault[i].getBase()))
auto val = LocationVault[i].getBase();
if (!AA->mayReadFromMemory(I, val))
continue;
if (llvm::all_of(I->getAllOperands(), [&AA = AA, &val](Operand &op) {
return AA->isNoAlias(op.get(), val);
}))
continue;
S->stopTrackingLocation(S->BBWriteSetMid, i);
}
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8 changes: 8 additions & 0 deletions lib/SILOptimizer/Transforms/RedundantLoadElimination.cpp
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Expand Up @@ -980,6 +980,10 @@ void BlockState::processUnknownWriteInstForGenKillSet(RLEContext &Ctx,
LSLocation &R = Ctx.getLocation(i);
if (!AA->mayWriteToMemory(I, R.getBase()))
continue;
if (llvm::all_of(I->getAllOperands(), [&AA, &R](Operand &op) {
return AA->isNoAlias(op.get(), R.getBase());
}))
continue;
// MayAlias.
stopTrackingLocation(BBGenSet, i);
startTrackingLocation(BBKillSet, i);
Expand All @@ -999,6 +1003,10 @@ void BlockState::processUnknownWriteInstForRLE(RLEContext &Ctx,
LSLocation &R = Ctx.getLocation(i);
if (!AA->mayWriteToMemory(I, R.getBase()))
continue;
if (llvm::all_of(I->getAllOperands(), [&AA, &R](Operand &op) {
return AA->isNoAlias(op.get(), R.getBase());
}))
continue;
// MayAlias.
stopTrackingLocation(ForwardSetIn, i);
stopTrackingValue(ForwardValIn, i);
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40 changes: 40 additions & 0 deletions test/SILOptimizer/dead_store_elim.sil
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Expand Up @@ -1502,6 +1502,46 @@ bb0(%0 : $*foo):
return %20 : $()
}

class Foo {
@_hasStorage @_hasInitialValue var x: Int { get set }
deinit
init()
}

class Bar {
@_hasStorage @_hasInitialValue var x: Int { get set }
deinit
init()
}

// CHECK-LABEL: @unknown_unrelated_read
// CHECK: store
// CHECK-NOT: store
// CHECK-LABEL: end sil function 'unknown_unrelated_read'
sil hidden @unknown_unrelated_read : $@convention(thin) (@inout Int) -> () {
bb0(%0 : $*Int):
%1 = alloc_ref $Foo
%3 = integer_literal $Builtin.Int64, 0
%4 = struct $Int (%3 : $Builtin.Int64)
%5 = ref_element_addr %1 : $Foo, #Foo.x
store %4 to %5 : $*Int

%10 = alloc_ref [stack] $Bar
%12 = ref_element_addr %10 : $Bar, #Bar.x
%15 = integer_literal $Builtin.Int64, 1
%16 = struct $Int (%15 : $Builtin.Int64)
store %16 to %12 : $*Int

set_deallocating %10 : $Bar
dealloc_ref %10 : $Bar
dealloc_ref [stack] %10 : $Bar

copy_addr %5 to %0 : $*Int

%20 = tuple()
return %20 : $()
}

// Check that begin_access, end_access, strong_release, set_deallocating, and dealloc_ref don't prevent optimization.
// CHECK-LABEL: ignore_read_write
// CHECK: bb0
Expand Down