[lld] r359683 - [LLD] Emit dynamic relocations for references to script symbols in -pie links

[Ben Dunbobbin via llvm-commits]

Author: bd1976llvm
Date: Wed May  1 07:07:31 2019
New Revision: 359683

URL: http://llvm.org/viewvc/llvm-project?rev=359683&view=rev
Log:
[LLD] Emit dynamic relocations for references to script symbols in -pie links

https://reviews.llvm.org/D55423 caused LLD to stop emitting dynamic relocations for references to script symbols in -pie links.

This patch fixes that regression.

https://reviews.llvm.org/D61298

Added:
    lld/trunk/test/ELF/linkerscript/symbol-pie.s
Modified:
    lld/trunk/ELF/Relocations.cpp

Modified: lld/trunk/ELF/Relocations.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Relocations.cpp?rev=359683&r1=359682&r2=359683&view=diff
==============================================================================
--- lld/trunk/ELF/Relocations.cpp (original)
+++ lld/trunk/ELF/Relocations.cpp Wed May  1 07:07:31 2019
@@ -421,11 +421,6 @@ static bool isStaticLinkTimeConstant(Rel
   if (E == R_SIZE)
     return true;
 
-  // We set the final symbols values for linker script defined symbols later.
-  // They always can be computed as a link time constant.
-  if (Sym.ScriptDefined)
-    return true;
-
   // For the target and the relocation, we want to know if they are
   // absolute or relative.
   bool AbsVal = isAbsoluteValue(Sym);
@@ -449,6 +444,11 @@ static bool isStaticLinkTimeConstant(Rel
   if (Sym.isUndefWeak())
     return true;
 
+  // We set the final symbols values for linker script defined symbols later.
+  // They always can be computed as a link time constant.
+  if (Sym.ScriptDefined)
+      return true;
+
   error("relocation " + toString(Type) + " cannot refer to absolute symbol: " +
         toString(Sym) + getLocation(S, Sym, RelOff));
   return true;

Added: lld/trunk/test/ELF/linkerscript/symbol-pie.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/linkerscript/symbol-pie.s?rev=359683&view=auto
==============================================================================
--- lld/trunk/test/ELF/linkerscript/symbol-pie.s (added)
+++ lld/trunk/test/ELF/linkerscript/symbol-pie.s Wed May  1 07:07:31 2019
@@ -0,0 +1,19 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: echo "SECTIONS { .data 0x2000 : { foo = .; *(.data) } }" > %t.script
+# RUN: ld.lld -pie -o %t --script %t.script %t.o
+# RUN: llvm-readobj -r %t | FileCheck %s
+
+## Position independent executables require dynamic
+## relocations for references to non-absolute script
+## symbols.
+
+# CHECK:      Relocations [
+# CHECK-NEXT:  Section ({{.*}}) .rela.dyn {
+# CHECK-NEXT:    0x2000 R_X86_64_RELATIVE - 0x2000
+# CHECK-NEXT:  }
+# CHECK-NEXT: ]
+
+.data
+.quad foo