[WebAssembly] Add support for using a wasm global for the stack pointer.

This replaces the __stack_pointer variable which was allocated in linear
memory.

llvm-svn: 296201

1 files changed, 23 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
index c198a262241..5a285935e2b 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
@@ -84,6 +84,13 @@ void WebAssemblyTargetAsmStreamer::emitLocal(ArrayRef<MVT> Types) {
   }
 }
 
+void WebAssemblyTargetAsmStreamer::emitGlobal(ArrayRef<MVT> Types) {
+  if (!Types.empty()) {
+    OS << "\t.globalvar  \t";
+    PrintTypes(OS, Types);
+  }
+}
+
 void WebAssemblyTargetAsmStreamer::emitEndFunc() { OS << "\t.endfunc\n"; }
 
 void WebAssemblyTargetAsmStreamer::emitIndirectFunctionType(
@@ -124,6 +131,10 @@ void WebAssemblyTargetELFStreamer::emitLocal(ArrayRef<MVT> Types) {
     Streamer.EmitIntValue(int64_t(WebAssembly::toValType(Type)), 1);
 }
 
+void WebAssemblyTargetELFStreamer::emitGlobal(ArrayRef<MVT> Types) {
+  llvm_unreachable(".globalvar encoding not yet implemented");
+}
+
 void WebAssemblyTargetELFStreamer::emitEndFunc() {
   Streamer.EmitIntValue(WebAssembly::End, 1);
 }
@@ -185,6 +196,18 @@ void WebAssemblyTargetWasmStreamer::emitLocal(ArrayRef<MVT> Types) {
   }
 }
 
+void WebAssemblyTargetWasmStreamer::emitGlobal(ArrayRef<MVT> Types) {
+  // Encode the globals use by the funciton into the special .global_variables
+  // section. This will later be decoded and turned into contents for the
+  // Globals Section.
+  Streamer.PushSection();
+  Streamer.SwitchSection(Streamer.getContext()
+                                 .getWasmSection(".global_variables", 0, 0));
+  for (MVT Ty : Types)
+    Streamer.EmitIntValue(uint64_t(WebAssembly::toValType(Ty)), 1);
+  Streamer.PopSection();
+}
+
 void WebAssemblyTargetWasmStreamer::emitEndFunc() {
   llvm_unreachable(".end_func is not needed for direct wasm output");
 }