From 737cd213e359c2862253c3a1ee443419566e90b9 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Tue, 5 Oct 2010 18:01:23 +0000
Subject: [PATCH] Implement a simple alias case and refactor the code a bit so
 that the isInSymtab and isLocal logic in the two loops don't get easily out
 of sync.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115643 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/MC/ELFObjectWriter.cpp | 52 +++++++++++++++++++++++++-------------
 test/MC/ELF/alias.s        | 22 ++++++++++++++++
 2 files changed, 57 insertions(+), 17 deletions(-)
 create mode 100644 test/MC/ELF/alias.s

diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index b33b0470308..72a6cbd5ef4 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -692,6 +692,29 @@ ELFObjectWriterImpl::getSymbolIndexInSymbolTable(const MCAssembler &Asm,
   return SD.getIndex() + NumRegularSections + /* empty symbol */ 1;
 }
 
+static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data,
+                       bool Used) {
+  const MCSymbol &Symbol = Data.getSymbol();
+  if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined())
+    return false;
+
+  if (!Used && Symbol.isTemporary())
+    return false;
+
+  return true;
+}
+
+static bool isLocal(const MCSymbolData &Data) {
+  if (Data.isExternal())
+    return false;
+
+  const MCSymbol &Symbol = Data.getSymbol();
+  if (Symbol.isUndefined() && !Symbol.isVariable())
+    return false;
+
+  return true;
+}
+
 void ELFObjectWriterImpl::ComputeSymbolTable(MCAssembler &Asm) {
   // FIXME: Is this the correct place to do this?
   if (NeedsGOT) {
@@ -718,14 +741,10 @@ void ELFObjectWriterImpl::ComputeSymbolTable(MCAssembler &Asm) {
          ie = Asm.symbol_end(); it != ie; ++it) {
     const MCSymbol &Symbol = it->getSymbol();
 
-    // Ignore non-linker visible symbols.
-    if (!Asm.isSymbolLinkerVisible(Symbol))
+    if (!isInSymtab(Asm, *it, UsedInReloc.count(&Symbol)))
       continue;
 
-    if (it->isExternal() || Symbol.isUndefined())
-      continue;
-
-    if (Symbol.isTemporary() && !UsedInReloc.count(&Symbol))
+    if (!isLocal(*it))
       continue;
 
     uint64_t &Entry = StringIndexMap[Symbol.getName()];
@@ -743,7 +762,14 @@ void ELFObjectWriterImpl::ComputeSymbolTable(MCAssembler &Asm) {
       MSD.SectionIndex = ELF::SHN_ABS;
       LocalSymbolData.push_back(MSD);
     } else {
-      MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
+      const MCSymbol *SymbolP = &Symbol;
+      if (Symbol.isVariable()) {
+        const MCExpr *Value = Symbol.getVariableValue();
+        assert (Value->getKind() == MCExpr::SymbolRef && "Unimplemented");
+        const MCSymbolRefExpr *Ref = static_cast<const MCSymbolRefExpr*>(Value);
+        SymbolP = &Ref->getSymbol();
+      }
+      MSD.SectionIndex = SectionIndexMap.lookup(&SymbolP->getSection());
       assert(MSD.SectionIndex && "Invalid section index!");
       LocalSymbolData.push_back(MSD);
     }
@@ -754,18 +780,10 @@ void ELFObjectWriterImpl::ComputeSymbolTable(MCAssembler &Asm) {
          ie = Asm.symbol_end(); it != ie; ++it) {
     const MCSymbol &Symbol = it->getSymbol();
 
-    // Ignore non-linker visible symbols.
-    if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined())
-      continue;
-
-    if (!it->isExternal() && !Symbol.isUndefined())
-      continue;
-
-    if (Symbol.isVariable())
+    if (!isInSymtab(Asm, *it, UsedInReloc.count(&Symbol)))
       continue;
 
-    if (Symbol.isUndefined() && !UsedInReloc.count(&Symbol)
-        && Symbol.isTemporary())
+    if (isLocal(*it))
       continue;
 
     uint64_t &Entry = StringIndexMap[Symbol.getName()];
diff --git a/test/MC/ELF/alias.s b/test/MC/ELF/alias.s
new file mode 100644
index 00000000000..5da8635c1f9
--- /dev/null
+++ b/test/MC/ELF/alias.s
@@ -0,0 +1,22 @@
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | elf-dump  | FileCheck %s
+
+foo:
+bar = foo
+
+// CHECK:       # Symbol 1
+// CHECK-NEXT:  (('st_name', 5) # 'bar'
+// CHECK-NEXT:   ('st_bind', 0)
+// CHECK-NEXT:   ('st_type', 0)
+// CHECK-NEXT:   ('st_other', 0)
+// CHECK-NEXT:   ('st_shndx', 1)
+// CHECK-NEXT:   ('st_value', 0)
+// CHECK-NEXT:   ('st_size', 0)
+// CHECK-NEXT:  ),
+// CHECK-NEXT:  # Symbol 2
+// CHECK-NEXT:  (('st_name', 1) # 'foo'
+// CHECK-NEXT:   ('st_bind', 0)
+// CHECK-NEXT:   ('st_type', 0)
+// CHECK-NEXT:   ('st_other', 0)
+// CHECK-NEXT:   ('st_shndx', 1)
+// CHECK-NEXT:   ('st_value', 0)
+// CHECK-NEXT:   ('st_size', 0)
-- 
2.34.1