From 26b697c4fe89c6357aa8488200b969fed59a0dc8 Mon Sep 17 00:00:00 2001
From: Sam Clegg <sbc@chromium.org>
Date: Fri, 22 Feb 2019 21:41:42 +0000
Subject: [PATCH] [WebAssembly] MC: Handle aliases of aliases

Differential Revision: https://reviews.llvm.org/D58417

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@354694 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/MC/WasmObjectWriter.cpp           | 13 +++++++------
 test/MC/WebAssembly/function-alias.ll |  9 +++++++++
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/lib/MC/WasmObjectWriter.cpp b/lib/MC/WasmObjectWriter.cpp
index d8dfc57c416..9ca239e3b47 100644
--- a/lib/MC/WasmObjectWriter.cpp
+++ b/lib/MC/WasmObjectWriter.cpp
@@ -558,12 +558,13 @@ void WasmObjectWriter::recordRelocation(MCAssembler &Asm,
 }
 
 static const MCSymbolWasm *resolveSymbol(const MCSymbolWasm &Symbol) {
-  if (Symbol.isVariable()) {
-    const MCExpr *Expr = Symbol.getVariableValue();
+  const MCSymbolWasm* Ret = &Symbol;
+  while (Ret->isVariable()) {
+    const MCExpr *Expr = Ret->getVariableValue();
     auto *Inner = cast<MCSymbolRefExpr>(Expr);
-    return cast<MCSymbolWasm>(&Inner->getSymbol());
+    Ret = cast<MCSymbolWasm>(&Inner->getSymbol());
   }
-  return &Symbol;
+  return Ret;
 }
 
 // Compute a value to write into the code at the location covered
@@ -1422,12 +1423,12 @@ uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm,
     LLVM_DEBUG(dbgs() << WS.getName() << ": weak alias of '" << *ResolvedSym
                       << "'\n");
 
-    if (WS.isFunction()) {
+    if (ResolvedSym->isFunction()) {
       assert(WasmIndices.count(ResolvedSym) > 0);
       uint32_t WasmIndex = WasmIndices.find(ResolvedSym)->second;
       WasmIndices[&WS] = WasmIndex;
       LLVM_DEBUG(dbgs() << "  -> index:" << WasmIndex << "\n");
-    } else if (WS.isData()) {
+    } else if (ResolvedSym->isData()) {
       assert(DataLocations.count(ResolvedSym) > 0);
       const wasm::WasmDataReference &Ref =
           DataLocations.find(ResolvedSym)->second;
diff --git a/test/MC/WebAssembly/function-alias.ll b/test/MC/WebAssembly/function-alias.ll
index 0a3c53989bc..9fc91b6a8e2 100644
--- a/test/MC/WebAssembly/function-alias.ll
+++ b/test/MC/WebAssembly/function-alias.ll
@@ -5,8 +5,10 @@ target triple = "wasm32-unknown-unknown-wasm"
 
 @foo = alias i8, bitcast (i8* ()* @func to i8*)
 @bar = alias i8* (), i8* ()* @func
+@bar2 = alias i8* (), i8* ()* @bar
 
 define i8* @func() {
+  call i8* @bar2();
   ret i8* @foo;
 }
 
@@ -19,6 +21,13 @@ define i8* @func() {
 ; CHECK-NEXT:     ElementIndex: 0x0
 ; CHECK-NEXT:   }
 ; CHECK-NEXT:   Symbol {
+; CHECK-NEXT:     Name: bar2
+; CHECK-NEXT:     Type: FUNCTION (0x0)
+; CHECK-NEXT:     Flags [ (0x0)
+; CHECK-NEXT:     ]
+; CHECK-NEXT:     ElementIndex: 0x0
+; CHECK-NEXT:   }
+; CHECK-NEXT:   Symbol {
 ; CHECK-NEXT:     Name: foo
 ; CHECK-NEXT:     Type: FUNCTION (0x0)
 ; CHECK-NEXT:     Flags [ (0x0)
-- 
2.50.1