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[IRBuilder] Tunnel block inputs into nested scopes #9337

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ad26e65
[IRBuilder] Use multiple scratch locals for inputs
tlively Nov 1, 2026
7f8938a
[IRBuilder] Tunnel block inputs into nested scopes
tlively Nov 1, 2026
26fcd22
simplify popInputs, add assertion
tlively Nov 2, 2026
d79a69e
Fix ASSERT_OK redefinition and NDEBUG evaluation
tlively Nov 3, 2026
30bb2d1
Merge branch 'ir-builder-input-locals' into ir-builder-tunnel-params
tlively Nov 3, 2026
e135f2a
Merge remote-tracking branch 'origin/main' into ir-builder-tunnel-params
tlively Nov 4, 2026
2bbd16a
fix bugs found by bots
tlively Nov 5, 2026
6517b07
whitespace
tlively Nov 5, 2026
be7ad62
Merge remote-tracking branch 'origin/main' into ir-builder-tunnel-params
tlively Nov 9, 2026
6857a61
Merge remote-tracking branch 'origin/main' into ir-builder-tunnel-params
tlively Nov 11, 2026
3f5549d
simplify and address comments
tlively Nov 11, 2026
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85 changes: 55 additions & 30 deletions src/wasm/wasm-ir-builder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -901,16 +901,57 @@ Result<> IRBuilder::pushScope(ScopeCtx&& scope) {
scope.startPos = lastBinaryPos;
lastBinaryPos = *binaryPos;
}
// Tunnel catch pops directly into unnamed blocks. Allow this even when the
// block has no input type so we can round-trip WAT without the printer
// needing to synthesize block input types, as well as when the block's input
// type matches the pop's type.
bool isUnnamedBlock = scope.getBlock() && !scope.getBlock()->name;
bool hasPop =
getScope().exprStack.size() == 1 && getScope().exprStack[0]->is<Pop>();
if (isUnnamedBlock && hasPop &&
(scope.inputType == Type::none ||
scope.inputType == getScope().exprStack[0]->type)) {
// Move the pop into the new scope.
auto* pop = getScope().exprStack.back();
getScope().exprStack.pop_back();
scopeStack.emplace_back(std::move(scope));
pushSynthetic(pop);
// If this unnamed block later receives a name from a branch targeting it,
// the nested pop will need to be fixed up.
scopeStack[0].noteSyntheticBlock();
return Ok{};
}

bool hasInput = scope.inputType != Type::none;
if (hasInput && !scope.isDelimiter()) {
auto inputs = ChildPopper{*this}.popInputs(scope.inputType);
CHECK_ERR(inputs);
const auto& parentLocals = getScope().inputLocals;
// The new scope may only receive a suffix of the outer scope's parameters,
// so match inputs starting from the remaining size of the outer stack
// rather than from the beginning.
size_t baseIndex = getScope().exprStack.size();
scope.inputLocals.reserve(inputs->size());
for (size_t i = 0; i < inputs->size(); ++i) {
auto scratch = addScratchLocal(scope.inputType[i]);
CHECK_ERR(scratch);
scope.inputLocals.push_back(*scratch);
pushSynthetic(builder.makeLocalSet(*scratch, (*inputs)[i]));
// Reuse the enclosing scope's scratch local rather than allocating a new
// one when an input comes directly from an enclosing scope's input.
// Earlier inputs that allocate new scratch locals (e.g. due to type
// widening) are copied before this scope starts, which safely reorders
// scratch `local.get`s past any subsequent reused inputs.
auto* input = (*inputs)[i];
size_t parentIndex = baseIndex + i;
bool isInputGet =
parentIndex < parentLocals.size() && input->is<LocalGet>() &&
input->cast<LocalGet>()->index == parentLocals[parentIndex] &&
input->type == scope.inputType[i];
if (isInputGet) {
scope.inputLocals.push_back(parentLocals[parentIndex]);
} else {
auto scratch = addScratchLocal(scope.inputType[i]);
CHECK_ERR(scratch);
scope.inputLocals.push_back(*scratch);
pushSynthetic(builder.makeLocalSet(*scratch, input));
}
}
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}
scopeStack.emplace_back(std::move(scope));
Expand Down Expand Up @@ -2022,38 +2063,22 @@ Result<> IRBuilder::makeUnreachable() {
Result<> IRBuilder::makePop(Type type) {
// We don't actually want to create a new Pop expression here because we
// already create them automatically when starting a legacy catch block that
// needs one. Just verify that the Pop we are being asked to make is the same
// type as the Pop we have already made, and move it into the current scope if
// we have entered unnamed blocks since the catch began. (Note that the block
// may receive a name later, if we encounter a break to it, if we process
// that after the pop. In that case, the fixups that run later will have work
// to do.)
ScopeCtx* catchScope = nullptr;
for (int i = int(scopeStack.size()) - 1; i >= 0; --i) {
auto& scope = scopeStack[i];
if (scope.getCatch()) {
catchScope = &scope;
break;
}
auto* block = scope.getBlock();
if (!block || block->name || !scope.exprStack.empty()) {
break;
// needs one (and move them into nested unnamed blocks in pushScope). Just
// verify that the Pop we are being asked to make is the same type as the Pop
// we have already made.
auto& scope = getScope();
if (scope.exprStack.size() != 1 || !scope.exprStack[0]->is<Pop>()) {
if (auto* tryy = scope.getCatch();
tryy && wasm.getTag(tryy->catchTags.back())->params() == Type::none) {
return Err{"cannot pop from empty tag"};
}
}
if (!catchScope || catchScope->exprStack.size() != 1 ||
!catchScope->exprStack[0]->is<Pop>()) {
return Err{
"pop instructions may only appear at the beginning of catch blocks"};
}
auto* pop = catchScope->exprStack[0];
auto expectedType = pop->type;
if (!Type::isSubType(expectedType, type)) {
auto expectedType = scope.exprStack[0]->type;
if (type != expectedType) {
return Err{std::string("Expected pop of type ") + expectedType.toString()};
}
if (catchScope != &getScope()) {
catchScope->exprStack.pop_back();
pushSynthetic(pop);
}
return Ok{};
}

Expand Down
49 changes: 2 additions & 47 deletions test/lit/basic/exception-handling-legacy.wast
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Original file line number Diff line number Diff line change
Expand Up @@ -1181,39 +1181,6 @@
)
)

;; CHECK-TEXT: (func $pop-can-be-supertype (type $0)
;; CHECK-TEXT-NEXT: (try
;; CHECK-TEXT-NEXT: (do
;; CHECK-TEXT-NEXT: )
;; CHECK-TEXT-NEXT: (catch $e-eqref
;; CHECK-TEXT-NEXT: (drop
;; CHECK-TEXT-NEXT: (pop eqref)
;; CHECK-TEXT-NEXT: )
;; CHECK-TEXT-NEXT: )
;; CHECK-TEXT-NEXT: )
;; CHECK-TEXT-NEXT: )
;; CHECK-BIN: (func $pop-can-be-supertype (type $0)
;; CHECK-BIN-NEXT: (try
;; CHECK-BIN-NEXT: (do
;; CHECK-BIN-NEXT: )
;; CHECK-BIN-NEXT: (catch $e-eqref
;; CHECK-BIN-NEXT: (drop
;; CHECK-BIN-NEXT: (pop eqref)
;; CHECK-BIN-NEXT: )
;; CHECK-BIN-NEXT: )
;; CHECK-BIN-NEXT: )
;; CHECK-BIN-NEXT: )
(func $pop-can-be-supertype
(try
(do)
(catch $e-eqref
(drop
(pop anyref) ;; pop can be supertype
)
)
)
)

;; CHECK-TEXT: (func $catchless-try-with-inner-delegate (type $0)
;; CHECK-TEXT-NEXT: (try $label$0
;; CHECK-TEXT-NEXT: (do
Expand Down Expand Up @@ -1780,18 +1747,6 @@
;; CHECK-BIN-NODEBUG-NEXT: )

;; CHECK-BIN-NODEBUG: (func $22 (type $0)
;; CHECK-BIN-NODEBUG-NEXT: (try
;; CHECK-BIN-NODEBUG-NEXT: (do
;; CHECK-BIN-NODEBUG-NEXT: )
;; CHECK-BIN-NODEBUG-NEXT: (catch $tag$3
;; CHECK-BIN-NODEBUG-NEXT: (drop
;; CHECK-BIN-NODEBUG-NEXT: (pop eqref)
;; CHECK-BIN-NODEBUG-NEXT: )
;; CHECK-BIN-NODEBUG-NEXT: )
;; CHECK-BIN-NODEBUG-NEXT: )
;; CHECK-BIN-NODEBUG-NEXT: )

;; CHECK-BIN-NODEBUG: (func $23 (type $0)
;; CHECK-BIN-NODEBUG-NEXT: (try $label
;; CHECK-BIN-NODEBUG-NEXT: (do
;; CHECK-BIN-NODEBUG-NEXT: (try
Expand All @@ -1808,7 +1763,7 @@
;; CHECK-BIN-NODEBUG-NEXT: (unreachable)
;; CHECK-BIN-NODEBUG-NEXT: )

;; CHECK-BIN-NODEBUG: (func $24 (type $0)
;; CHECK-BIN-NODEBUG: (func $23 (type $0)
;; CHECK-BIN-NODEBUG-NEXT: (block
;; CHECK-BIN-NODEBUG-NEXT: (block
;; CHECK-BIN-NODEBUG-NEXT: )
Expand All @@ -1821,7 +1776,7 @@
;; CHECK-BIN-NODEBUG-NEXT: (nop)
;; CHECK-BIN-NODEBUG-NEXT: )

;; CHECK-BIN-NODEBUG: (func $25 (type $0)
;; CHECK-BIN-NODEBUG: (func $24 (type $0)
;; CHECK-BIN-NODEBUG-NEXT: (if
;; CHECK-BIN-NODEBUG-NEXT: (try (result i32)
;; CHECK-BIN-NODEBUG-NEXT: (do
Expand Down
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