[WebAssembly] Use __stack_pointer global when writing wasm binary

This ensures that symbolic relocations are generated for stack
pointer manipulations.

These relocations are of type R_WEBASSEMBLY_GLOBAL_INDEX_LEB.
This change also adds support for reading relocations of this
type in WasmObjectFile.cpp.

Since its a globally imported symbol this does mean that
the get_global/set_global instruction won't be valid until
the objects are linked that global used in no longer an
imported global.

Differential Revision: https://reviews.llvm.org/D34172

llvm-svn: 305616

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
index 19e14f3261a..9cf77829f3b 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
@@ -68,6 +68,8 @@ WebAssemblyWasmObjectWriter::getRelocType(const MCValue &Target,
   bool IsFunction = IsFunctionExpr(Fixup.getValue());
 
   switch (unsigned(Fixup.getKind())) {
+  case WebAssembly::fixup_code_global_index:
+    return wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB;
   case WebAssembly::fixup_code_sleb128_i32:
     if (IsFunction)
       return wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB;