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Handle more instructions in SROA #83353

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52b4ce3
Support mark_dependence in SROA
meg-gupta Jul 25, 2025
063dc8c
Support destroy_addr in SROA
meg-gupta Jul 25, 2025
c2e29e7
NFC: Add debug messages to COWOpts
meg-gupta Jul 25, 2025
887e323
[NFC] Add some more unit tests
meg-gupta Jul 25, 2025
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12 changes: 10 additions & 2 deletions lib/SILOptimizer/Transforms/COWOpts.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -137,16 +137,20 @@ bool COWOptsPass::optimizeBeginCOW(BeginCOWMutationInst *BCM) {
if (SILPhiArgument *arg = dyn_cast<SILPhiArgument>(v)) {
if (handled.insert(arg)) {
SmallVector<SILValue, 4> incomingVals;
if (!arg->getIncomingPhiValues(incomingVals))
if (!arg->getIncomingPhiValues(incomingVals)) {
LLVM_DEBUG(llvm::dbgs() << "Bailing out, found non-phi: " << arg);
return false;
}
for (SILValue incomingVal : incomingVals) {
LLVM_DEBUG(llvm::dbgs() << "Incoming phi value: " << incomingVal);
workList.push_back(incomingVal);
}
}
} else if (auto *ECM = dyn_cast<EndCOWMutationInst>(v)) {
if (endCOWMutationsFound.insert(ECM))
endCOWMutationInsts.push_back(ECM);
} else {
LLVM_DEBUG(llvm::dbgs() << "Found unhandled SILValue: " << v);
return false;
}
}
Expand Down Expand Up @@ -230,8 +234,10 @@ bool COWOptsPass::optimizeBeginCOW(BeginCOWMutationInst *BCM) {
// buffer is stored to.
if (numStoresFound != 0) {
// Avoid quadratic behavior. Usually this limit is not exceeded.
if (numStoresFound * numLoadsFound > 128)
if (numStoresFound * numLoadsFound > 128) {
LLVM_DEBUG(llvm::dbgs() << "Bailing out, threshold reached\n");
return false;
}
for (SILInstruction *load : potentialLoadInsts) {
for (SILValue storeAddr : storeAddrs) {
if (!AA || AA->mayReadFromMemory(load, storeAddr)) {
Expand All @@ -245,6 +251,8 @@ bool COWOptsPass::optimizeBeginCOW(BeginCOWMutationInst *BCM) {
}
}

LLVM_DEBUG(llvm::dbgs() << "Success: marking keep_unique\n");

// Replace the uniqueness result of the begin_cow_mutation with an integer
// literal of "true".
SILBuilderWithScope B(BCM);
Expand Down
31 changes: 28 additions & 3 deletions lib/SILOptimizer/Transforms/SILSROA.cpp
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Expand Up @@ -175,10 +175,16 @@ bool SROAMemoryUseAnalyzer::analyze() {
continue;
}

if (isa<DeallocStackInst>(User)) {
if (isa<DeallocStackInst>(User) || isa<DestroyAddrInst>(User) ) {
// We can ignore the dealloc_stack.
continue;
}

if (auto *mdi = dyn_cast<MarkDependenceInst>(User)) {
if (mdi->getBase() == Operand->get()) {
continue;
}
}

// Otherwise we do not understand this instruction, so bail.
LLVM_DEBUG(llvm::dbgs() <<" Found unknown user, pointer escapes!\n");
Expand Down Expand Up @@ -288,11 +294,30 @@ void SROAMemoryUseAnalyzer::chopUpAlloca(std::vector<AllocStackInst *> &Worklist
// up allocas, we also chop up the relevant dealloc stack insts.
if (auto *DSI = dyn_cast<DeallocStackInst>(User)) {
LLVM_DEBUG(llvm::dbgs() << " Found DeallocStackInst!\n");
// Create the allocations in reverse order.
// Create the deallocations in reverse order.
for (auto *NewAI : llvm::reverse(NewAllocations))
B.createDeallocStack(DSI->getLoc(), SILValue(NewAI));
ToRemove.push_back(DSI);
}
if (auto *DAI = dyn_cast<DestroyAddrInst>(User)) {
LLVM_DEBUG(llvm::dbgs() << " Found DestroyAddrInst!\n");
for (auto *NewAI : NewAllocations) {
auto &srcTL = B.getTypeLowering(NewAI->getType());
srcTL.emitDestroyAddress(B, DAI->getLoc(), SILValue(NewAI));
}
ToRemove.push_back(DAI);
}
if (auto *origMDI = dyn_cast<MarkDependenceInst>(User)) {
LLVM_DEBUG(llvm::dbgs() << " Found MarkDependenceInst!\n");
auto value = origMDI->getValue();
for (auto *NewAI : NewAllocations) {
auto *newMdi = B.createMarkDependence(origMDI->getLoc(), value,
NewAI, origMDI->dependenceKind());
value = newMdi;
}
origMDI->replaceAllUsesWith(value);
ToRemove.push_back(origMDI);
}
}

for (auto *Operand : getDebugUses(SILValue(AI))) {
Expand Down Expand Up @@ -324,7 +349,7 @@ void SROAMemoryUseAnalyzer::chopUpAlloca(std::vector<AllocStackInst *> &Worklist
ToRemove.push_back(DVI);
}

// Remove the old DeallocStackInst/DebugValueInst instructions.
// Remove the old instructions.
for (auto *DSI : ToRemove) {
DSI->eraseFromParent();
}
Expand Down
100 changes: 100 additions & 0 deletions test/SILOptimizer/sroa_ossa.sil
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Original file line number Diff line number Diff line change
Expand Up @@ -494,6 +494,24 @@ bb0(%0 : @owned $NotTrivial):
return %6 : $()
}

// CHECK-LABEL: sil [ossa] @struct_with_obj_fields_destroy_addr :
// CHECK: [[VAR_1:%[0-9]+]] = alloc_stack $Obj
// CHECK: [[VAR_2:%[0-9]+]] = alloc_stack $Obj
// CHECK-LABEL: } // end sil function 'struct_with_obj_fields_destroy_addr'
sil [ossa] @struct_with_obj_fields_destroy_addr : $@convention(thin) (@owned NotTrivial) -> () {
bb0(%0 : @owned $NotTrivial):
%1 = alloc_stack $NotTrivial
store %0 to [init] %1 : $*NotTrivial
%2 = function_ref @use_obj : $@convention(thin) (@owned Obj) -> ()
%3 = struct_element_addr %1 : $*NotTrivial, #NotTrivial.y
%4 = load [copy] %3 : $*Obj
apply %2(%4) : $@convention(thin) (@owned Obj) -> ()
destroy_addr %1
dealloc_stack %1
%6 = tuple ()
return %6 : $()
}

// CHECK-LABEL: sil [ossa] @struct_with_obj_fields_multiple_stores :
// CHECK: bb0([[ARG_0:%[0-9]+]] : @owned $NotTrivial, [[ARG_1:%[0-9]+]] : @owned $NotTrivial):
// CHECK: [[VAR_1:%[0-9]+]] = alloc_stack $Obj
Expand Down Expand Up @@ -583,3 +601,85 @@ bb6:
%res = tuple ()
return %res : $()
}


struct Wrapper {
var array: Array<Int>
}

struct DoubleWrapper {
var array1: Array<Int>
var array2: Array<Int>
}

sil @get_span_from_array : $@convention(thin) (@guaranteed Array<Int>) -> Span<Int>
sil @get_span_from_wrapper : $@convention(thin) (@guaranteed Wrapper) -> Span<Int>
sil @get_span_from_doublewrapper : $@convention(thin) (@guaranteed DoubleWrapper) -> Span<Int>
sil @use_span : $@convention(thin) (Span<Int>) -> ()

// CHECK-LABEL: sil [ossa] @struct_with_dependence1 :
// CHECK: alloc_stack $Array
// CHECK-LABEL: } // end sil function 'struct_with_dependence1'
sil [ossa] @struct_with_dependence1 : $@convention(thin) (@owned Array<Int>) -> () {
bb0(%0 : @owned $Array<Int>):
%stk = alloc_stack $Wrapper
%3 = struct_element_addr %stk : $*Wrapper, #Wrapper.array
store %0 to [init] %3
%4 = load_borrow %3
%2 = function_ref @get_span_from_array : $@convention(thin) (@guaranteed Array<Int>) -> Span<Int>
%5 = apply %2(%4) : $@convention(thin) (@guaranteed Array<Int>) -> Span<Int>
%6 = mark_dependence [nonescaping] %5 on %stk
%7 = function_ref @use_span : $@convention(thin) (Span<Int>) -> ()
%8 = apply %7(%6) : $@convention(thin) (Span<Int>) -> ()
end_borrow %4
%9 = load [take] %stk
destroy_value %9
dealloc_stack %stk
%r = tuple ()
return %r : $()
}

// CHECK-LABEL: sil [ossa] @struct_with_dependence2 :
// CHECK: alloc_stack $Array
// CHECK-LABEL: } // end sil function 'struct_with_dependence2'
sil [ossa] @struct_with_dependence2 : $@convention(thin) (@owned Array<Int>) -> () {
bb0(%0 : @owned $Array<Int>):
%stk = alloc_stack $Wrapper
%3 = struct_element_addr %stk : $*Wrapper, #Wrapper.array
store %0 to [init] %3
%4 = load [copy] %stk
%2 = function_ref @get_span_from_wrapper : $@convention(thin) (@guaranteed Wrapper) -> Span<Int>
%5 = apply %2(%4) : $@convention(thin) (@guaranteed Wrapper) -> Span<Int>
%6 = mark_dependence [nonescaping] %5 on %stk
%7 = function_ref @use_span : $@convention(thin) (Span<Int>) -> ()
%8 = apply %7(%6) : $@convention(thin) (Span<Int>) -> ()
destroy_value %4
destroy_addr %stk
dealloc_stack %stk
%r = tuple ()
return %r : $()
}

// CHECK-LABEL: sil [ossa] @struct_with_dependence3 :
// CHECK: alloc_stack $Array
// CHECK: alloc_stack $Array
// CHECK-LABEL: } // end sil function 'struct_with_dependence3'
sil [ossa] @struct_with_dependence3 : $@convention(thin) (@owned Array<Int>, @owned Array<Int>) -> () {
bb0(%0 : @owned $Array<Int>, %1 : @owned $Array<Int>):
%stk = alloc_stack $DoubleWrapper
%3 = struct_element_addr %stk : $*DoubleWrapper, #DoubleWrapper.array1
store %0 to [init] %3
%3b = struct_element_addr %stk : $*DoubleWrapper, #DoubleWrapper.array2
store %1 to [init] %3b
%4 = load [copy] %stk
%2 = function_ref @get_span_from_doublewrapper : $@convention(thin) (@guaranteed DoubleWrapper) -> Span<Int>
%5 = apply %2(%4) : $@convention(thin) (@guaranteed DoubleWrapper) -> Span<Int>
%6 = mark_dependence [nonescaping] %5 on %stk
%7 = function_ref @use_span : $@convention(thin) (Span<Int>) -> ()
%8 = apply %7(%6) : $@convention(thin) (Span<Int>) -> ()
destroy_value %4
destroy_addr %stk
dealloc_stack %stk
%r = tuple ()
return %r : $()
}