Difference between revisions of "WebAssembly/Roadmap"
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Revision as of 19:57, 14 March 2021
Short-Term
These steps are critical for completion in order to have wasm a full scope CPU target for FPC compiler
Feature | Status | Description |
---|---|---|
Assembly (textual wasm) | working | Pick an assembler utility that's sequence instruction (FPC) friendly
FPC should produce a textual assembly file. Currently, FPC uses the LLVM assembler llvm-mc. |
Linking | working | Pick an linker utility that's sequence instruction (FPC) friendly.
Linker is a moving target. As a new feature is added, the linking needs to be re-verified. Currently, FPC uses the LLVM linker. |
Basic function calls and local variables | working | Implement direct function calls, with passing basic parameters (that don't require any memory. I.e. int and floats) |
Verify float-point values | in progress | As the float points are being converted from the textual format. it's necessary to make sure that the proper values are generated |
Global variables | working | Implement symbol reference to global variables (basic or complex)
Consider linking - as the index of symbols can change. (Wasm binaries are index based ) |
Stack/Call frame support | working | WebAssembly doesn't have any native stack and/or frame support.
It has to be emulated using global and local variables. Blocking issue: https://github.com/WebAssembly/wabt/issues/1199 |
Indirect function calls | working | WebAssembly has a specific way of indirect calls
Needed for vmt and procedure variables (callback) calls |
VMT | working | Support for calls via virtual method table |
RTL.Memory Manager | working | |
RTL.(Ansi/Wide) String Manager | working | |
RTL.WASI.Console I/O | working | Standard input, standard output and error output (stderr) works on the WASI target. |
RTL.WASI.File I/O | in progress | The WASI target needs a mechanism for converting path names (both relative and absolute) to paths, relative to a given set of preopened directories (these are the directories you're given access to). Also, the concept of current directory needs to be emulated, too. |
Long-Term
Future improvements for wasm target. Some of those are nice to have, but not critical. Others are difficult to implement or need features of WebAssembly, which haven't been standardized yet.
Feature | Status | Description |
---|---|---|
Debug Info | in progress | There's experimental DWARF support for WebAssembly, but it isn't working yet and the debugging tools for WebAssembly aren't very mature at this point even for C and C++. |
Internal Writer | not implemented | The binary wasm format is well defined and could be implemented within FPC |
Internal Linker | not implemented | |
GOTO support | not implemented | Goto is difficult to implement, due to WebAssembly's lack of labels and jumps. It requires all gotos to be converted to structured flow, such as loops and break/continue. This requires implementing a complex algorithm, such as Relooper or Stackifier. Useful read: [1] |
Exceptions support | not implemented | Exceptions for WebAssembly are not standardized yet. FPC's default implementation relies on setjmp/longjmp, which are not available in WebAssembly. |