diff options
| author | Konstantin Yegupov <[email protected]> | 2018-12-25 17:17:32 +0000 |
|---|---|---|
| committer | Ayke van Laethem <[email protected]> | 2019-01-03 18:09:33 +0100 |
| commit | a8dd82538e9b6cc6a1b7b100e638072e9b1d291a (patch) | |
| tree | 1fbd004465410c96e064c661e4c5891d8c6d1bc8 /docs | |
| parent | dccfae485c9c5830e1ec012dfb9eb5af5fd10699 (diff) | |
| download | tinygo-a8dd82538e9b6cc6a1b7b100e638072e9b1d291a.tar.gz tinygo-a8dd82538e9b6cc6a1b7b100e638072e9b1d291a.zip | |
all: add flag to enable i64 parameters in WebAssembly
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/internals.rst | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/docs/internals.rst b/docs/internals.rst index 5cf61d611..14091d9bb 100644 --- a/docs/internals.rst +++ b/docs/internals.rst @@ -130,8 +130,8 @@ somewhat compatible with the C calling convention but with a few quirks: pointers. This avoids some overhead in the C calling convention and makes the work of the LLVM optimizers easier. - * The WebAssembly target never exports or imports a ``i64`` (``int64``, - ``uint64``) parameter. Instead, it replaces them with ``i64*``, allocating + * The WebAssembly target by default doesn't export or import ``i64`` (``int64``, + ``uint64``) parameters. Instead, it replaces them with ``i64*``, allocating the value on the stack. In other words, imported functions are called with a 64-bit integer on the stack and exported functions must be called with a pointer to a 64-bit integer somewhere in linear memory. @@ -144,10 +144,15 @@ somewhat compatible with the C calling convention but with a few quirks: calling convention workaround may be removed. Also see `this wasm-bindgen issue <https://github.com/rustwasm/wasm-bindgen/issues/35>`_. + Currently there are also non-browser WebAssembly execution environments + that do not have this limitation. Use the `-wasm-abi=generic` flag to remove + the behavior described above and enable emitting functions with i64 + parameters directly. + * The WebAssembly target does not return variables directly that cannot be - handled by JavaScript (``struct``, ``i64``, multiple return values, etc). - Instead, they are stored into a pointer passed as the first parameter by the - caller. + handled by JavaScript (see above about ``i64``, also ``struct``, multiple + return values, etc). Instead, they are stored into a pointer passed as the + first parameter by the caller. This is the calling convention as implemented by LLVM, with the extension that ``i64`` return values are returned in the same way as aggregate types. |