[PATCH] D30843: ELF: Resolve _end symbols correctly.

[Peter Collingbourne via Phabricator via llvm-commits]

pcc created this revision.

Fix a bug introduced in r297313 which caused them to resolve to the end
of the ELF header in PIEs and DSOs.


https://reviews.llvm.org/D30843

Files:
  lld/ELF/Writer.cpp
  lld/test/ELF/pre_init_fini_array_missing.s


Index: lld/test/ELF/pre_init_fini_array_missing.s
===================================================================
--- lld/test/ELF/pre_init_fini_array_missing.s
+++ lld/test/ELF/pre_init_fini_array_missing.s
@@ -1,6 +1,8 @@
 // RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
 // RUN: ld.lld %t -o %t2
 // RUN: llvm-objdump -d %t2 | FileCheck %s
+// RUN: ld.lld -pie %t -o %t3
+// RUN: llvm-objdump -d %t3 | FileCheck --check-prefix=PIE %s
 // REQUIRES: x86
 
 .globl _start
@@ -28,3 +30,14 @@
 // CHECK-NEXT:   20100f:    e8 ec ef df ff     callq    -2101268
 // CHECK-NEXT:   201014:    e8 e7 ef df ff     callq    -2101273
 // CHECK-NEXT:   201019:    e8 e2 ef df ff     callq    -2101278
+
+// In position-independent binaries, they resolve to the image base.
+
+// PIE:      Disassembly of section .text:
+// PIE-NEXT: _start:
+// PIE-NEXT:     1000:	e8 fb ef ff ff 	callq	-4101
+// PIE-NEXT:     1005:	e8 f6 ef ff ff 	callq	-4106
+// PIE-NEXT:     100a:	e8 f1 ef ff ff 	callq	-4111
+// PIE-NEXT:     100f:	e8 ec ef ff ff 	callq	-4116
+// PIE-NEXT:     1014:	e8 e7 ef ff ff 	callq	-4121
+// PIE-NEXT:     1019:	e8 e2 ef ff ff 	callq	-4126
Index: lld/ELF/Writer.cpp
===================================================================
--- lld/ELF/Writer.cpp
+++ lld/ELF/Writer.cpp
@@ -1203,10 +1203,15 @@
   auto Define = [&](StringRef Start, StringRef End, OutputSection *OS) {
     // These symbols resolve to the image base if the section does not exist.
     // A special value -1 indicates end of the section.
-    if (!OS && Config->pic())
-      OS = Out::ElfHeader;
-    addOptionalRegular<ELFT>(Start, OS, 0);
-    addOptionalRegular<ELFT>(End, OS, OS ? -1 : 0);
+    if (OS) {
+      addOptionalRegular<ELFT>(Start, OS, 0);
+      addOptionalRegular<ELFT>(End, OS, -1);
+    } else {
+      if (Config->pic())
+        OS = Out::ElfHeader;
+      addOptionalRegular<ELFT>(Start, OS, 0);
+      addOptionalRegular<ELFT>(End, OS, 0);
+    }
   };
 
   Define("__preinit_array_start", "__preinit_array_end", Out::PreinitArray);


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