Allocate __dso_handle in s2wasm

Unlike asm.js modules, wasm modules cannot have imported/extern
objects. So allocate __dso_handle (which is traditionally defined in
a crtbegin or similar toolchain file linked with the user code) in s2wasm.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/s2wasm.h b/src/s2wasm.h
index 19b3db79d..c85a214a1 100644
--- a/src/s2wasm.h
+++ b/src/s2wasm.h
@@ -78,6 +78,11 @@ class S2WasmBuilder {
     // Place the stack pointer at the bottom of the linear memory, to keep its
     // address small (and thus with a small encoding).
     placeStackPointer(stackAllocation);
+    // Allocate __dso_handle. For asm.js, emscripten provides this in JS, but
+    // wasm modules can't import data objects. Its value is 0 for the main
+    // executable, which is all we have with static linking. In the future this
+    // can go in a crtbegin or similar file.
+    allocateStatic(4, 4, "__dso_handle");
     process();
     // Place the stack after the user's static data, to keep those addresses
     // small.