From 03f1b74aed795110f040b7588c8921c5de4bf1ea Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Thu, 11 Nov 2010 16:48:11 +0000
Subject: [PATCH] Fix the symbol index of weak references. Also make
 RecordRelocation a bit easier to read by having const references to the
 symbol, aliased symbol and renamed symbol.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118793 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/MC/ELFObjectWriter.cpp  | 34 +++++++++----------------
 test/MC/ELF/weakref-reloc.s | 49 +++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 22 deletions(-)
 create mode 100644 test/MC/ELF/weakref-reloc.s

diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index 4adc188b616..f84164d253b 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -669,16 +669,16 @@ void ELFObjectWriterImpl::RecordRelocation(const MCAssembler &Asm,
   int64_t Addend = 0;
   int Index = 0;
   int64_t Value = Target.getConstant();
-  const MCSymbol *Symbol = 0;
-  const MCSymbol *Renamed = 0;
+  const MCSymbol &Symbol = Target.getSymA()->getSymbol();
+  const MCSymbol &ASymbol = AliasedSymbol(Symbol);
+  const MCSymbol *RenamedP = Renames.lookup(&Symbol);
+  if (!RenamedP)
+    RenamedP = &ASymbol;
+  const MCSymbol &Renamed = *RenamedP;
 
   bool IsPCRel = isFixupKindX86PCRel(Fixup.getKind());
   if (!Target.isAbsolute()) {
-    Symbol = &AliasedSymbol(Target.getSymA()->getSymbol());
-    Renamed = Renames.lookup(Symbol);
-    if (!Renamed)
-      Renamed = &Target.getSymA()->getSymbol();
-    MCSymbolData &SD = Asm.getSymbolData(*Symbol);
+    MCSymbolData &SD = Asm.getSymbolData(Symbol);
     MCFragment *F = SD.getFragment();
 
     if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
@@ -695,15 +695,6 @@ void ELFObjectWriterImpl::RecordRelocation(const MCAssembler &Asm,
       Value += b - a;
     }
 
-    // Check that this case has already been fully resolved before we get
-    // here.
-    if (Symbol->isDefined() && !SD.isExternal() &&
-        IsPCRel &&
-        &Fragment->getParent()->getSection() == &Symbol->getSection()) {
-      llvm_unreachable("We don't need a relocation in this case.");
-      return;
-    }
-
     bool RelocOnSymbol = ShouldRelocOnSymbol(SD, Target, *Fragment);
     if (!RelocOnSymbol) {
       Index = F->getParent()->getOrdinal();
@@ -712,11 +703,10 @@ void ELFObjectWriterImpl::RecordRelocation(const MCAssembler &Asm,
       // Offset of the symbol in the section
       Value += Layout.getSymbolAddress(&SD) - Layout.getSectionAddress(FSD);
     } else {
-      UsedInReloc.insert(Renamed);
-      MCSymbolData &RenamedSD = Asm.getSymbolData(*Renamed);
-      if (RenamedSD.getFlags() & ELF_Other_Weakref) {
-        WeakrefUsedInReloc.insert(Symbol);
-      }
+      if (Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref)
+        WeakrefUsedInReloc.insert(&Renamed);
+      else
+        UsedInReloc.insert(&Renamed);
       Index = -1;
     }
     Addend = Value;
@@ -864,7 +854,7 @@ void ELFObjectWriterImpl::RecordRelocation(const MCAssembler &Asm,
 
   ERE.Index = Index;
   ERE.Type = Type;
-  ERE.Symbol = Renamed;
+  ERE.Symbol = &Renamed;
 
   ERE.r_offset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
 
diff --git a/test/MC/ELF/weakref-reloc.s b/test/MC/ELF/weakref-reloc.s
new file mode 100644
index 00000000000..580d754bc6a
--- /dev/null
+++ b/test/MC/ELF/weakref-reloc.s
@@ -0,0 +1,49 @@
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | elf-dump  | FileCheck %s
+
+// Test that the relocations point to the correct symbols. We used to get the
+// symbol index wrong for weakrefs when creating _GLOBAL_OFFSET_TABLE_.
+
+	.weakref	bar,foo
+        call    zed@PLT
+	call	bar
+
+// CHECK:      # Symbol 0x00000004
+// CHECK-NEXT: (('st_name', 0x00000009) # '_GLOBAL_OFFSET_TABLE_'
+// CHECK-NEXT:  ('st_bind', 0x00000001)
+// CHECK-NEXT:  ('st_type', 0x00000000)
+// CHECK-NEXT:  ('st_other', 0x00000000)
+// CHECK-NEXT:  ('st_shndx', 0x00000000)
+// CHECK-NEXT:  ('st_value', 0x00000000)
+// CHECK-NEXT:  ('st_size', 0x00000000)
+// CHECK-NEXT: ),
+// CHECK-NEXT: # Symbol 0x00000005
+// CHECK-NEXT: (('st_name', 0x00000001) # 'foo'
+// CHECK-NEXT:  ('st_bind', 0x00000002)
+// CHECK-NEXT:  ('st_type', 0x00000000)
+// CHECK-NEXT:  ('st_other', 0x00000000)
+// CHECK-NEXT:  ('st_shndx', 0x00000000)
+// CHECK-NEXT:  ('st_value', 0x00000000)
+// CHECK-NEXT:  ('st_size', 0x00000000)
+// CHECK-NEXT: ),
+// CHECK-NEXT: # Symbol 0x00000006
+// CHECK-NEXT: (('st_name', 0x00000005) # 'zed'
+// CHECK-NEXT:  ('st_bind', 0x00000001)
+// CHECK-NEXT:  ('st_type', 0x00000000)
+// CHECK-NEXT:  ('st_other', 0x00000000)
+// CHECK-NEXT:  ('st_shndx', 0x00000000)
+// CHECK-NEXT:  ('st_value', 0x00000000)
+// CHECK-NEXT:  ('st_size', 0x00000000)
+// CHECK-NEXT: ),
+
+// CHECK:      # Relocation 0x00000000
+// CHECK-NEXT: (('r_offset', 0x00000001)
+// CHECK-NEXT:  ('r_sym', 0x00000006)
+// CHECK-NEXT:  ('r_type', 0x00000004)
+// CHECK-NEXT:  ('r_addend', 0xfffffffc)
+// CHECK-NEXT: ),
+// CHECK-NEXT: # Relocation 0x00000001
+// CHECK-NEXT: (('r_offset', 0x00000006)
+// CHECK-NEXT:  ('r_sym', 0x00000005)
+// CHECK-NEXT:  ('r_type', 0x00000002)
+// CHECK-NEXT:  ('r_addend', 0xfffffffc)
+// CHECK-NEXT: ),