Split construction, scanning, and building phases of S2WasmBuilder (#400)

Instead of doing all of the S2Wasm work in the constructor, split
construction, scanning (to determine implemented functions) and building
of the wasm module.

This allows the linker to get the symbol information (e.g. implemented
functions) without having to build an entire module (which will be
useful for archives) and to allow the linker to link a new object into
the existing one by building the wasm module in place on the existing
module.

1 files changed, 7 insertions, 1 deletions

diff --git a/src/s2wasm-main.cpp b/src/s2wasm-main.cpp
index 435eb560f..7b0e4c179 100644
--- a/src/s2wasm-main.cpp
+++ b/src/s2wasm-main.cpp
@@ -104,7 +104,13 @@ int main(int argc, const char *argv[]) {
   Linker linker(globalBase, stackAllocation, initialMem, maxMem,
                 ignoreUnknownSymbols, startFunction, options.debug);
 
-  S2WasmBuilder s2wasm(linker.getOutput(), input.c_str(), options.debug);
+  S2WasmBuilder mainbuilder(input.c_str(), options.debug);
+  linker.linkObject(mainbuilder);
+
+  // In the future, there will be code to open additional files/buffers and
+  // link additional objects, as well as archive members (which only get linked if needed), e.g.:
+  // S2WasmBuilder lazyObject(some_other_buffer, options.debug)
+  // linker.linkLazyObject(lazyObject); // calls builder.scan to get symbol info, then build
 
   linker.layout();