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Diffstat (limited to 'lld/docs/WebAssembly.rst')
| -rw-r--r-- | lld/docs/WebAssembly.rst | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/lld/docs/WebAssembly.rst b/lld/docs/WebAssembly.rst index 016fdd74ec3..7858e0d2af9 100644 --- a/lld/docs/WebAssembly.rst +++ b/lld/docs/WebAssembly.rst @@ -95,6 +95,26 @@ behavior of a traditional ELF linker, and in particular the ELF port of lld. For more specific details on how this is achieved see the tool conventions on linking_. +Function Signatrues +~~~~~~~~~~~~~~~~~~~ + +One way in which the WebAssembly linker differs from traditional native linkers +is that function signature checking is strict in WebAssembly. It is a +validation error for a module to contain to call site that doesn't agree with +the target signature. Even though this is undefined behavior in C/C++ its not +uncommon to find this in real world C/C++ programs. For example, a call site in +one complication unit which calls a function defined in another complication +unit but with too many arguments. + +In order not to generate such invalid modules lld has two modes of handling such +mismatches: it can simply error out or it can create stub functions that will +trap at runtime (functions that contain only an ``unreachable`` instruction) +and use these stub functions at the otherwise invalid call sites. + +The the default befviour is to generate these stub function and to produce +a warning. The ``--falal-warnings`` flag can be used to disable this behaviour +and error out if mismatched are found. + Imports and Exports ~~~~~~~~~~~~~~~~~~~ |
