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WebAssembly support in LLDB #150449

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WebAssembly support in LLDB#150449
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JDevlieghere
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backend:WebAssemblylldbmetaissueIssue to collect references to a group of similar or related issues.

Description

@JDevlieghere
JDevlieghere
opened on Jul 24, 2025

Meta-issue to track support for debugging WebAssembly (Wasm) with LLDB.

Core Support

  • #150143 Add WebAssembly Process Plugin
  • #151010 Support DW_OP_WASM_location in DWARFExpression
  • #151056 Implement RegisterContextWasm
  • #171507 Add WebAssembly platform
  • #175263 Make PlatformWasm a RemoteAwarePlatform
  • #188751 Add PlatformWebInspectorWasm (Safari/Web Inspector Wasm debugging)

Object/Symbol File

  • #153093 Support parsing the Wasm symbol table
  • #153494 Support parsing data symbols from the Wasm name section
  • #153634 Create sections for Wasm segments
  • #170960 Handle imports when parsing Wasm name sections
  • #204496 Report a generic wasm32 architecture for Wasm object files
  • #206840 Create a BSS section for WebAssembly object files
  • #206832 Recover mangled symbol names from DWARF on WebAssembly
  • #207235 Synthesize data symbols for WebAssembly from DWARF
  • #208061 Give Wasm stack frames a synthetic call frame address

Wasm Runtime

  • #190476 Inherit Host::GetEnvironment() when launching a Wasm runtime
  • #193115 Don't enable ASLR for the Wasm runtime
  • #206780 Forward the inferior's environment to the Wasm runtime

Expression Evaluation

  • TBD

Bug Fixes

  • #154433 Improve error handling in ObjectFileWasm
  • #153332 Use numeric_limits for all overflow checks in ObjectFileWasm
  • #154727 Correctly parse Wasm segments
  • #162942 Use the correct Wasm register context
  • #176464 Fix llvm_unreachable for invalid Wasm address
  • #178299 Fix unchecked llvm::Expected in ObjectFileWasm
  • #190093 Skip local variable declarations at start of Wasm function
  • #192893 Fix crash when evaluating expressions in Wasm targets
  • #193124 Skip memory region probing in FindSpace when process can't JIT
  • #194001 Handle partial memory region coverage in IRMemoryMap::FindSpace
  • #196368 Immediately connect in webinspector-wasm
  • #198700 Fall back to FindProcesses in webinspector-wasm GetProcessInfo
  • #198701 Recheck connection state in webinspector-wasm EnsureConnected
  • #199124 Disable formatters for Wasm object format (bytecode)
  • #204480 Skip the prologue when a function's entry has no line row

Testing

Activity

  1. JDevlieghere
    self-assigned this
    on Jul 24, 2025
  2. llvmbot
    added
    new issue
    on Jul 24, 2025
  3. EugeneZelenko
    added
    metaissueIssue to collect references to a group of similar or related issues.
    lldb
    backend:WebAssembly
    and removed
    new issue
    on Jul 24, 2025

  4. llvmbot commented on Jul 24, 2025

    @llvmbot
    llvmbot
    on Jul 24, 2025
    Member

    @llvm/issue-subscribers-backend-webassembly

    Author: Jonas Devlieghere (JDevlieghere)

    Details Meta-issue to track support for debugging WebAssembly (Wasm) using the GDB Remote Protocol with Wasm-specific extensions.

  5. llvmbot commented on Jul 24, 2025

    @llvmbot
    llvmbot
    on Jul 24, 2025
    Member

    @llvm/issue-subscribers-lldb

    Author: Jonas Devlieghere (JDevlieghere)

    Details Meta-issue to track support for debugging WebAssembly (Wasm) using the GDB Remote Protocol with Wasm-specific extensions.

  6. DavidSpickett commented on Jul 25, 2025

    @DavidSpickett
    DavidSpickett
    on Jul 25, 2025
    Contributor

    Now linked from the website - c63c2f4.

  7. dschuff commented on Jul 25, 2025

    @dschuff
    dschuff
    on Jul 25, 2025
    Member

    In case it's useful, the sources for Chrome's wasm debugging devtools extension can be found here, although there's unfortunately no good documentation. WasmVendorPlugins.cc defines wasm-specific integrations, although there are also some places where it uses private APIs that predate the plugins.

  8. DavidSpickett commented on Apr 21, 2026

    @DavidSpickett
    DavidSpickett
    on Apr 21, 2026
    Contributor

    The description's tasks are all done but I assume that expressions needs to be done.

    FYI we have these settings:

      target.expr-alloc-address                        -- Start address within the process address space of
                                                      memory allocation for expression evaluation.
  target.expr-alloc-align                          -- Alignment for each memory allocation for
                                                      expression evaluation.
  target.expr-alloc-size                           -- Amount of memory in bytes to allocate for
                                                      expression evaluation.

    Which I think were added for embedded devices, but you could try using them as a first step for wasm.

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