From 12203cc7c3f7392d62556946a10b2f10205ea63d Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Sun, 21 Nov 2010 00:48:25 +0000
Subject: [PATCH] Handle PCRel relocations with absolute values. Fixes PR8656.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119917 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/MC/ELFObjectWriter.cpp   | 32 +++++++++++++++++++++++---------
 test/MC/ELF/relocation-386.s |  7 +++++++
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index 4e09b4df195..4ea6308f45c 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -948,10 +948,12 @@ void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm,
   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
     ELFRelocationEntry entry = Relocs[e - i - 1];
 
-    if (entry.Index < 0)
+    if (!entry.Index)
+      ;
+    else if (entry.Index < 0)
       entry.Index = getSymbolIndexInSymbolTable(Asm, entry.Symbol);
     else
-      entry.Index += LocalSymbolData.size() + 1;
+      entry.Index += LocalSymbolData.size();
     if (Is64Bit) {
       String64(*F, entry.r_offset);
 
@@ -1085,13 +1087,22 @@ bool ELFObjectWriter::IsFixupFullyResolved(const MCAssembler &Asm,
   }
 
   const MCSection *SectionB = 0;
+  const MCSymbol *SymbolB = 0;
   if (const MCSymbolRefExpr *B = Target.getSymB()) {
-    SectionB = &B->getSymbol().AliasedSymbol().getSection();
+    SymbolB = &B->getSymbol();
+    SectionB = &SymbolB->AliasedSymbol().getSection();
   }
 
   if (!BaseSection)
     return SectionA == SectionB;
 
+  if (SymbolB)
+    return false;
+
+  // Absolute address but PCrel instruction, so we need a relocation.
+  if (!SymbolA)
+    return false;
+
   // FIXME: This is in here just to match gnu as output. If the two ends
   // are in the same section, there is nothing that the linker can do to
   // break it.
@@ -1099,7 +1110,7 @@ bool ELFObjectWriter::IsFixupFullyResolved(const MCAssembler &Asm,
   if (DataA.isExternal())
     return false;
 
-  return !SectionB && BaseSection == SectionA;
+  return BaseSection == SectionA;
 }
 
 void ELFObjectWriter::CreateGroupSections(MCAssembler &Asm,
@@ -1391,12 +1402,14 @@ void X86ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
   int64_t Addend = 0;
   int Index = 0;
   int64_t Value = Target.getConstant();
-  const MCSymbol &Symbol = Target.getSymA()->getSymbol();
-  const MCSymbol &ASymbol = Symbol.AliasedSymbol();
-  const MCSymbol *RelocSymbol = SymbolToReloc(Asm, Target, *Fragment);
+  const MCSymbol *RelocSymbol = NULL;
 
   bool IsPCRel = isFixupKindX86PCRel(Fixup.getKind());
   if (!Target.isAbsolute()) {
+    const MCSymbol &Symbol = Target.getSymA()->getSymbol();
+    const MCSymbol &ASymbol = Symbol.AliasedSymbol();
+    RelocSymbol = SymbolToReloc(Asm, Target, *Fragment);
+
     if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
       const MCSymbol &SymbolB = RefB->getSymbol();
       MCSymbolData &SDB = Asm.getSymbolData(SymbolB);
@@ -1415,7 +1428,7 @@ void X86ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
       MCSymbolData &SD = Asm.getSymbolData(ASymbol);
       MCFragment *F = SD.getFragment();
 
-      Index = F->getParent()->getOrdinal();
+      Index = F->getParent()->getOrdinal() + 1;
 
       MCSectionData *FSD = F->getParent();
       // Offset of the symbol in the section
@@ -1437,7 +1450,8 @@ void X86ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
 
   // determine the type of the relocation
 
-  MCSymbolRefExpr::VariantKind Modifier = Target.getSymA()->getKind();
+  MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
+    MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
   unsigned Type;
   if (Is64Bit) {
     if (IsPCRel) {
diff --git a/test/MC/ELF/relocation-386.s b/test/MC/ELF/relocation-386.s
index c3903236187..48cdc353e30 100644
--- a/test/MC/ELF/relocation-386.s
+++ b/test/MC/ELF/relocation-386.s
@@ -97,6 +97,12 @@
 // CHECK-NEXT: (('r_offset', 0x00000043)
 // CHECK-NEXT:  ('r_sym', 0x0000000b)
 // CHECK-NEXT:  ('r_type', 0x00000020)
+// CHECK-NEXT: ),
+// Relocation 12 (calll 4096) is of type R_386_PC32
+// CHECK-NEXT: # Relocation 0x0000000c
+// CHECK-NEXT: (('r_offset', 0x00000048)
+// CHECK-NEXT:  ('r_sym', 0x00000000)
+// CHECK-NEXT:  ('r_type', 0x00000002)
 // CHECK-NEXT: ),
 
         .text
@@ -122,6 +128,7 @@ bar2:
         addl foo@GOTNTPOFF(%ebx), %ecx
         leal foo@TLSLDM(%ebx), %eax
         leal foo@DTPOFF(%eax), %edx
+        calll 4096
 
         .section	.rodata.str1.16,"aMS",@progbits,1
 .Lfoo:
-- 
2.34.1