[lld] r295936 - [ELF] Ignore R_*_NONE relocs when relocating non-alloc sections

[Petr Hosek via llvm-commits]

Author: phosek
Date: Thu Feb 23 00:22:28 2017
New Revision: 295936

URL: http://llvm.org/viewvc/llvm-project?rev=295936&view=rev
Log:
[ELF] Ignore R_*_NONE relocs when relocating non-alloc sections

We shouldn't report an error for R_*_NONE relocs since we're emitting
them when writing relocations to discarded sections.

Differential Revision: https://reviews.llvm.org/D30279

Added:
    lld/trunk/test/ELF/Inputs/relocatable-non-alloc.s
    lld/trunk/test/ELF/relocatable-non-alloc.s
Modified:
    lld/trunk/ELF/InputSection.cpp
    lld/trunk/ELF/Relocations.cpp
    lld/trunk/ELF/Relocations.h
    lld/trunk/ELF/Target.cpp

Modified: lld/trunk/ELF/InputSection.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputSection.cpp?rev=295936&r1=295935&r2=295936&view=diff
==============================================================================
--- lld/trunk/ELF/InputSection.cpp (original)
+++ lld/trunk/ELF/InputSection.cpp Thu Feb 23 00:22:28 2017
@@ -308,6 +308,7 @@ getRelocTargetVA(uint32_t Type, int64_t
                  const SymbolBody &Body, RelExpr Expr) {
   switch (Expr) {
   case R_HINT:
+  case R_NONE:
   case R_TLSDESC_CALL:
     llvm_unreachable("cannot relocate hint relocs");
   case R_TLSLD:
@@ -459,7 +460,10 @@ void InputSection<ELFT>::relocateNonAllo
       Addend += Target->getImplicitAddend(BufLoc, Type);
 
     SymbolBody &Sym = this->getFile<ELFT>()->getRelocTargetSym(Rel);
-    if (Target->getRelExpr(Type, Sym) != R_ABS) {
+    RelExpr Expr = Target->getRelExpr(Type, Sym);
+    if (Expr == R_NONE)
+      continue;
+    if (Expr != R_ABS) {
       error(this->getLocation<ELFT>(Offset) + ": has non-ABS reloc");
       return;
     }

Modified: lld/trunk/ELF/Relocations.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Relocations.cpp?rev=295936&r1=295935&r2=295936&view=diff
==============================================================================
--- lld/trunk/ELF/Relocations.cpp (original)
+++ lld/trunk/ELF/Relocations.cpp Thu Feb 23 00:22:28 2017
@@ -694,6 +694,11 @@ static void scanRelocs(InputSectionBase
       reportUndefined<ELFT>(Body, C, RI.r_offset);
 
     RelExpr Expr = Target->getRelExpr(Type, Body);
+
+    // Ignore "hint" relocations because they are only markers for relaxation.
+    if (isRelExprOneOf<R_HINT, R_NONE>(Expr))
+      continue;
+
     bool Preemptible = isPreemptible(Body, Type);
     Expr = adjustExpr(*File, Body, IsWrite, Expr, Type, Buf + RI.r_offset, C,
                       RI.r_offset);
@@ -732,9 +737,7 @@ static void scanRelocs(InputSectionBase
       continue;
     }
 
-    // Ignore "hint" and TLS Descriptor call relocation because they are
-    // only markers for relaxation.
-    if (isRelExprOneOf<R_HINT, R_TLSDESC_CALL>(Expr))
+    if (Expr == R_TLSDESC_CALL)
       continue;
 
     if (needsPlt(Expr) ||

Modified: lld/trunk/ELF/Relocations.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Relocations.h?rev=295936&r1=295935&r2=295936&view=diff
==============================================================================
--- lld/trunk/ELF/Relocations.h (original)
+++ lld/trunk/ELF/Relocations.h Thu Feb 23 00:22:28 2017
@@ -42,6 +42,7 @@ enum RelExpr {
   R_MIPS_TLSGD,
   R_MIPS_TLSLD,
   R_NEG_TLS,
+  R_NONE,
   R_PAGE_PC,
   R_PC,
   R_PLT,

Modified: lld/trunk/ELF/Target.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Target.cpp?rev=295936&r1=295935&r2=295936&view=diff
==============================================================================
--- lld/trunk/ELF/Target.cpp (original)
+++ lld/trunk/ELF/Target.cpp Thu Feb 23 00:22:28 2017
@@ -389,7 +389,7 @@ RelExpr X86TargetInfo::getRelExpr(uint32
   case R_386_TLS_LE_32:
     return R_NEG_TLS;
   case R_386_NONE:
-    return R_HINT;
+    return R_NONE;
   default:
     error(toString(S.File) + ": unknown relocation type: " + toString(Type));
     return R_HINT;
@@ -684,7 +684,7 @@ RelExpr X86_64TargetInfo<ELFT>::getRelEx
   case R_X86_64_GOTTPOFF:
     return R_GOT_PC;
   case R_X86_64_NONE:
-    return R_HINT;
+    return R_NONE;
   default:
     error(toString(S.File) + ": unknown relocation type: " + toString(Type));
     return R_HINT;
@@ -1715,7 +1715,7 @@ RelExpr ARMTargetInfo::getRelExpr(uint32
   case R_ARM_THM_MOVT_PREL:
     return R_PC;
   case R_ARM_NONE:
-    return R_HINT;
+    return R_NONE;
   case R_ARM_TLS_LE32:
     return R_TLS;
   }

Added: lld/trunk/test/ELF/Inputs/relocatable-non-alloc.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/Inputs/relocatable-non-alloc.s?rev=295936&view=auto
==============================================================================
--- lld/trunk/test/ELF/Inputs/relocatable-non-alloc.s (added)
+++ lld/trunk/test/ELF/Inputs/relocatable-non-alloc.s Thu Feb 23 00:22:28 2017
@@ -0,0 +1,6 @@
+.section .text.foo,"axG", at progbits,foo,comdat,unique,0
+foo:
+  nop
+
+.section .debug_info
+.long .text.foo

Added: lld/trunk/test/ELF/relocatable-non-alloc.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/relocatable-non-alloc.s?rev=295936&view=auto
==============================================================================
--- lld/trunk/test/ELF/relocatable-non-alloc.s (added)
+++ lld/trunk/test/ELF/relocatable-non-alloc.s Thu Feb 23 00:22:28 2017
@@ -0,0 +1,10 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t1.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %S/Inputs/relocatable-non-alloc.s -o %t2.o
+# RUN: ld.lld %t2.o %t2.o -r -o %t3.o
+# RUN: ld.lld %t1.o %t3.o -o %t.o | FileCheck -allow-empty %s
+
+# CHECK-NOT:  has non-ABS reloc
+
+.globl _start
+_start: