asm2wasm debuginfo (#895)

* parse file/line comments in asm.js into debug intrinsics

* convert debug intrinsics into annotations, and print them

* ignore --debuginfo if not emitting text, as wasm binaries don't support that yet

* emit full debug info when -g and emitting text; when -g and emitting binary, all we can do is the Names section

* update wasm.js

1 files changed, 10 insertions, 2 deletions

diff --git a/src/tools/asm2wasm.cpp b/src/tools/asm2wasm.cpp
index c880e7459..01602c8b7 100644
--- a/src/tools/asm2wasm.cpp
+++ b/src/tools/asm2wasm.cpp
@@ -84,7 +84,7 @@ int main(int argc, const char *argv[]) {
            [&wasmOnly](Options *o, const std::string &) {
              wasmOnly = true;
            })
-      .add("--debuginfo", "-g", "Emit names section and debug info",
+      .add("--debuginfo", "-g", "Emit names section and debug info (for debug info you must emit text, -S, for this to work)",
            Options::Arguments::Zero,
            [&](Options *o, const std::string &arguments) { debugInfo = true; })
       .add("--symbolmap", "-s", "Emit a symbol map (indexes => names)",
@@ -99,6 +99,12 @@ int main(int argc, const char *argv[]) {
                       });
   options.parse(argc, argv);
 
+  // finalize arguments
+  if (options.extra["output"].size() == 0) {
+    // when no output file is specified, we emit text to stdout
+    emitBinary = false;
+  }
+
   const auto &tm_it = options.extra.find("total memory");
   size_t totalMemory =
       tm_it == options.extra.end() ? 16 * 1024 * 1024 : atoi(tm_it->second.c_str());
@@ -109,6 +115,8 @@ int main(int argc, const char *argv[]) {
   }
 
   Asm2WasmPreProcessor pre;
+  // wasm binaries can contain a names section, but not full debug info
+  pre.debugInfo = debugInfo && !emitBinary;
   auto input(
       read_file<std::vector<char>>(options.extra["infile"], Flags::Text, options.debug ? Flags::Debug : Flags::Release));
   char *start = pre.process(input.data());
@@ -120,7 +128,7 @@ int main(int argc, const char *argv[]) {
   if (options.debug) std::cerr << "wasming..." << std::endl;
   Module wasm;
   wasm.memory.initial = wasm.memory.max = totalMemory / Memory::kPageSize;
-  Asm2WasmBuilder asm2wasm(wasm, pre.memoryGrowth, options.debug, imprecise, passOptions, runOptimizationPasses, wasmOnly);
+  Asm2WasmBuilder asm2wasm(wasm, pre, options.debug, imprecise, passOptions, runOptimizationPasses, wasmOnly);
   asm2wasm.processAsm(asmjs);
 
   // import mem init file, if provided