[lld] r328559 - [ELF] GotSection increment NumEntries when Target saves GlobalOffsetTable in the .got

[Zaara Syeda via llvm-commits]

Author: syzaara
Date: Mon Mar 26 10:50:52 2018
New Revision: 328559

URL: http://llvm.org/viewvc/llvm-project?rev=328559&view=rev
Log:
[ELF] GotSection increment NumEntries when Target saves GlobalOffsetTable in the .got

When the target saves ElfSym::GlobalOffsetTable in the .got rather than
.got.plt, Target->GotHeaderEntriesNum states the number of extra entries
required in the .got. Rather than having to add Target->GotHeaderEntriesNum to
NumEntries in every function which refers to NumEntries, this patch changes the
initial value of NumEntries in the constructor.

Differential Revision: https://reviews.llvm.org/D44744

Modified:
    lld/trunk/ELF/SyntheticSections.cpp
    lld/trunk/test/ELF/ppc64_entry_point.s

Modified: lld/trunk/ELF/SyntheticSections.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SyntheticSections.cpp?rev=328559&r1=328558&r2=328559&view=diff
==============================================================================
--- lld/trunk/ELF/SyntheticSections.cpp (original)
+++ lld/trunk/ELF/SyntheticSections.cpp Mon Mar 26 10:50:52 2018
@@ -587,10 +587,18 @@ void EhFrameSection::writeTo(uint8_t *Bu
 
 GotSection::GotSection()
     : SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
-                       Target->GotEntrySize, ".got") {}
+                       Target->GotEntrySize, ".got") {
+  // PPC64 saves the ElfSym::GlobalOffsetTable .TOC. as the first entry in the
+  // .got. If there are no references to .TOC. in the symbol table,
+  // ElfSym::GlobalOffsetTable will not be defined and we won't need to save
+  // .TOC. in the .got. When it is defined, we increase NumEntries by the number
+  // of entries used to emit ElfSym::GlobalOffsetTable.
+  if (ElfSym::GlobalOffsetTable && !Target->GotBaseSymInGotPlt)
+    NumEntries += Target->GotHeaderEntriesNum;
+}
 
 void GotSection::addEntry(Symbol &Sym) {
-  Sym.GotIndex = Target->GotHeaderEntriesNum + NumEntries;
+  Sym.GotIndex = NumEntries;
   ++NumEntries;
 }
 
@@ -622,7 +630,7 @@ uint64_t GotSection::getGlobalDynOffset(
 }
 
 void GotSection::finalizeContents() {
-  Size = (NumEntries + Target->GotHeaderEntriesNum) * Config->Wordsize;
+  Size = NumEntries * Config->Wordsize;
 }
 
 bool GotSection::empty() const {

Modified: lld/trunk/test/ELF/ppc64_entry_point.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/ppc64_entry_point.s?rev=328559&r1=328558&r2=328559&view=diff
==============================================================================
--- lld/trunk/test/ELF/ppc64_entry_point.s (original)
+++ lld/trunk/test/ELF/ppc64_entry_point.s Mon Mar 26 10:50:52 2018
@@ -1,7 +1,7 @@
 # REQUIRES: ppc
 # RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux %s -o %t
 # RUN: ld.lld %t -o %t2
-# RUN: llvm-objdump -d %t2 | FileCheck %s
+# RUN: llvm-objdump -D %t2 | FileCheck %s
 
 .text
 .abiversion 2
@@ -31,3 +31,6 @@ _start:
 // CHECK-NEXT: 10010004:       00 00 84 38     addi 4, 4, 0
 // CHECK-NEXT: 10010008:       02 00 a0 3c     lis 5, 2
 // CHECK-NEXT: 1001000c:       00 80 a5 38     addi 5, 5, -32768
+// CHECK: Disassembly of section .got:
+// CHECK-NEXT: .got:
+// CHECK-NEXT: 10020000:       00 80 02 10