Fix SafeHeap crash when start function calls an imported function#8306
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sumleo wants to merge 1 commit intoWebAssembly:mainfrom
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Fix SafeHeap crash when start function calls an imported function#8306sumleo wants to merge 1 commit intoWebAssembly:mainfrom
sumleo wants to merge 1 commit intoWebAssembly:mainfrom
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findCalledFunctions transitively walks all functions called from the start function to determine which functions should not be instrumented. When the start function calls an imported function, the import was added to the worklist and then FindAll<Call> was called on its null body, causing an assertion failure in the walker (assert(*currp) in wasm-traversal.h). Skip imported functions in the traversal since they have no body to walk.
kripken
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Feb 12, 2026
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Thanks, looks good aside from some test comments.
| @@ -0,0 +1,28 @@ | |||
| ;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited. | |||
| ;; RUN: wasm-opt %s --safe-heap --enable-threads --enable-simd -S -o - | filecheck %s | |||
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| ;; RUN: wasm-opt %s --safe-heap --enable-threads --enable-simd -S -o - | filecheck %s | |
| ;; RUN: wasm-opt %s --safe-heap -S -o - | filecheck %s |
These features are not used in the testcase.
| (import "env" "some_import" (func $import)) | ||
| ;; CHECK: (import "env" "emscripten_get_sbrk_ptr" (func $emscripten_get_sbrk_ptr (result i32))) | ||
| (import "env" "emscripten_get_sbrk_ptr" (func $emscripten_get_sbrk_ptr (result i32))) | ||
| (memory 1 1 shared) |
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| (memory 1 1 shared) | |
| (memory 1 1) |
No need for this to be shared.
| ;; CHECK: (import "env" "some_import" (func $import)) | ||
| (import "env" "some_import" (func $import)) | ||
| ;; CHECK: (import "env" "emscripten_get_sbrk_ptr" (func $emscripten_get_sbrk_ptr (result i32))) | ||
| (import "env" "emscripten_get_sbrk_ptr" (func $emscripten_get_sbrk_ptr (result i32))) |
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| (import "env" "emscripten_get_sbrk_ptr" (func $emscripten_get_sbrk_ptr (result i32))) |
No need for this import.
| (call $import) | ||
| ) | ||
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| (start $start) |
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By convention we put this before the first function (around line 16, here)
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Summary
findCalledFunctionsin SafeHeap transitively walks all functions called from the start function to determine which functions should not be instrumented. When the start function calls an imported function, the import was added to the worklist and thenFindAll<Call>was called on its null body, causing an assertion failure in the walker:Reproducer:
Fix
Skip imported functions in the traversal since they have no body to walk.
Test plan
test/lit/passes/safe-heap-start-import.wastwith a start function that calls an import