1 files changed, 46 insertions, 2 deletions
diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
index 3fb3e65fb91..2846ec5e933 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
@@ -14,9 +14,13 @@
 //===----------------------------------------------------------------------===//
 
 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "MCTargetDesc/WebAssemblyFixupKinds.h"
 #include "llvm/MC/MCFixup.h"
+#include "llvm/MC/MCSymbolWasm.h"
 #include "llvm/MC/MCWasmObjectWriter.h"
+#include "llvm/Support/Casting.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Wasm.h"
 using namespace llvm;
 
 namespace {
@@ -33,12 +37,52 @@ private:
 WebAssemblyWasmObjectWriter::WebAssemblyWasmObjectWriter(bool Is64Bit)
     : MCWasmObjectTargetWriter(Is64Bit) {}
 
+// Test whether the given expression computes a function address.
+static bool IsFunctionExpr(const MCExpr *Expr) {
+  if (const MCSymbolRefExpr *SyExp =
+          dyn_cast<MCSymbolRefExpr>(Expr))
+    return cast<MCSymbolWasm>(SyExp->getSymbol()).isFunction();
+
+  if (const MCBinaryExpr *BinOp =
+          dyn_cast<MCBinaryExpr>(Expr))
+    return IsFunctionExpr(BinOp->getLHS()) != IsFunctionExpr(BinOp->getRHS());
+
+  if (const MCUnaryExpr *UnOp =
+          dyn_cast<MCUnaryExpr>(Expr))
+    return IsFunctionExpr(UnOp->getSubExpr());
+
+  return false;
+}
+
 unsigned WebAssemblyWasmObjectWriter::getRelocType(MCContext &Ctx,
                                                    const MCValue &Target,
                                                    const MCFixup &Fixup,
                                                    bool IsPCRel) const {
-  llvm_unreachable("Relocations not yet implemented");
-  return 0;
+  // WebAssembly functions are not allocated in the data address space. To
+  // resolve a pointer to a function, we must use a special relocation type.
+  bool IsFunction = IsFunctionExpr(Fixup.getValue());
+
+  assert(!IsPCRel);
+  switch (unsigned(Fixup.getKind())) {
+  case WebAssembly::fixup_code_sleb128_i32:
+    if (IsFunction)
+      return wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB;
+    return wasm::R_WEBASSEMBLY_GLOBAL_ADDR_SLEB;
+  case WebAssembly::fixup_code_sleb128_i64:
+    llvm_unreachable("fixup_sleb128_i64 not implemented yet");
+  case WebAssembly::fixup_code_uleb128_i32:
+    if (IsFunction)
+      return wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB;
+    return wasm::R_WEBASSEMBLY_GLOBAL_ADDR_LEB;
+  case FK_Data_4:
+    if (IsFunction)
+      return wasm::R_WEBASSEMBLY_TABLE_INDEX_I32;
+    return wasm::R_WEBASSEMBLY_GLOBAL_ADDR_I32;
+  case FK_Data_8:
+    llvm_unreachable("FK_Data_8 not implemented yet");
+  default:
+    llvm_unreachable("unimplemented fixup kind");
+  }
 }
 
 MCObjectWriter *llvm::createWebAssemblyWasmObjectWriter(raw_pwrite_stream &OS,