[WebAssembly] Emit .import_global assembler directives

Support a new assembler directive, .import_global, to declare imported
global variables (i.e. those with external linkage and no
initializer). The linker turns these into wasm imports.

Patch by Jacob Gravelle

Differential Revision: https://reviews.llvm.org/D26875

llvm-svn: 288296

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
index f0886880802..3cee8b2a184 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
@@ -80,6 +80,10 @@ void WebAssemblyTargetAsmStreamer::emitIndirectFunctionType(
   OS << '\n';
 }
 
+void WebAssemblyTargetAsmStreamer::emitGlobalImport(StringRef name) {
+  OS << "\t.import_global\t" << name << '\n';
+}
+
 void WebAssemblyTargetAsmStreamer::emitIndIdx(const MCExpr *Value) {
   OS << "\t.indidx  \t" << *Value << '\n';
 }
@@ -111,3 +115,6 @@ void WebAssemblyTargetELFStreamer::emitIndirectFunctionType(
   // Nothing to emit here. TODO: Re-design how linking works and re-evaluate
   // whether it's necessary for .o files to declare indirect function types.
 }
+
+void WebAssemblyTargetELFStreamer::emitGlobalImport(StringRef name) {
+}
\ No newline at end of file