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Fix #8785: StackEntry wasm stack type invariants and unreachable parser regressions #8978

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Fix #8785: StackEntry wasm stack type invariants and unreachable parser regressions #8978

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a81f7d1
Fix #8785 StackEntry wasm stack type invariants
ANAMASGARD Aug 6, 2026
0e656c1
Fix StackEntry regressions for try/return_call and unreachable CF scopes
ANAMASGARD Aug 7, 2026
3c49092
Fix unreachable stack popping with concrete values
ANAMASGARD Aug 7, 2026
abd506b
Fix unreachable fallback when void entries mask stack values
ANAMASGARD Aug 7, 2026
47a61c2
Fix unreachable barrier handling in IRBuilder stack analysis.
ANAMASGARD Aug 7, 2026
6c63e5d
Also hoist unreachable-typed void control flow for drop operands.
ANAMASGARD Aug 7, 2026
0e9a13f
Update lit expectations for corrected unreachable IR packaging.
ANAMASGARD Aug 7, 2026
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20 changes: 19 additions & 1 deletion src/wasm-ir-builder.h
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,12 @@ class IRBuilder : public UnifiedExpressionVisitor<IRBuilder, Result<>> {
// Like visit, but pushes the expression onto the stack as-is without popping
// any children or refinalization.
void push(Expression*, Origin origin = Origin::Binary);
// Push a control flow construct using its declared Wasm stack result type,
// which may differ from its Binaryen IR type when the construct is typed
// unreachable internally.
void pushControlFlow(Expression* expr,
Type wasmStackResult,
Origin origin = Origin::Binary);
void pushSynthetic(Expression* expr) { push(expr, Origin::Synthetic); }

// Set the debug location to be attached to the next visited, created, or
Expand Down Expand Up @@ -309,6 +315,14 @@ class IRBuilder : public UnifiedExpressionVisitor<IRBuilder, Result<>> {
// when visiting the beginnings of try blocks.
Result<> visitPop(Pop*) { return Ok{}; }

// An entry on the expression stack, tracking both the Binaryen IR node and
// the Wasm operand-stack type it produces. These may differ for unreachable
// control flow (see StackIRGenerator::makeStackInst in wasm-stack.cpp).
struct StackEntry {
Expression* expr;
Type wasmStackType;
};

private:
Module& wasm;
Function* func = nullptr;
Expand All @@ -332,7 +346,11 @@ class IRBuilder : public UnifiedExpressionVisitor<IRBuilder, Result<>> {

struct ChildPopper;

Result<> validateTypeAnnotation(Type type, Expression* child);
Result<> validateTypeAnnotation(HeapType type, Expression* child);

void applyDebugLoc(Expression* expr);
void pushStackEntry(Expression* expr, Type wasmStackType, Origin origin);

// The context for a single block scope, including the instructions parsed
// inside that scope so far and the ultimate result type we expect this block
Expand Down Expand Up @@ -418,7 +436,7 @@ class IRBuilder : public UnifiedExpressionVisitor<IRBuilder, Result<>> {
std::vector<Name> outputLabels;

// The stack of instructions being built in this scope.
std::vector<Expression*> exprStack;
std::vector<StackEntry> exprStack;

// Whether we have seen an unreachable instruction and are in
// stack-polymorphic unreachable mode.
Expand Down
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