[PATCH] D62365: ELF: Don't reuse a thunk in a different partition.

[Peter Collingbourne via Phabricator via llvm-commits]

pcc created this revision.
pcc added reviewers: ruiu, grimar, MaskRay, peter.smith.
Herald added subscribers: arichardson, emaste.
Herald added a reviewer: espindola.
Herald added a project: LLVM.

There's no guarantee that the other partition will be loaded, so it
can't be reused.

Depends on D60353 <https://reviews.llvm.org/D60353>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D62365

Files:
  lld/ELF/Relocations.cpp
  lld/ELF/Relocations.h
  lld/test/ELF/partition-thunk-reuse.s


Index: lld/test/ELF/partition-thunk-reuse.s
===================================================================
--- /dev/null
+++ lld/test/ELF/partition-thunk-reuse.s
@@ -0,0 +1,33 @@
+// REQUIRES: arm
+// RUN: llvm-mc %s -o %t.o -filetype=obj --triple=armv7-unknown-linux -arm-add-build-attributes
+// RUN: ld.lld %t.o -o %t --export-dynamic --gc-sections
+// RUN: llvm-nm %t | FileCheck %s
+
+// CHECK: __Thumbv7ABSLongThunk__start
+// CHECK: __Thumbv7ABSLongThunk__start
+
+.thumb
+
+.section .llvm_sympart.g1,"",%llvm_sympart
+.asciz "part1"
+.4byte f1
+
+.section .llvm_sympart.g2,"",%llvm_sympart
+.asciz "part2"
+.4byte f2
+
+.section .text._start,"ax",%progbits
+.globl _start
+_start:
+bx lr
+.zero 17*1048576
+
+.section .text.f1,"aw",%progbits
+.globl f1
+f1:
+b _start
+
+.section .text.f2,"ax",%progbits
+.globl f2
+f2:
+b _start
Index: lld/ELF/Relocations.h
===================================================================
--- lld/ELF/Relocations.h
+++ lld/ELF/Relocations.h
@@ -135,7 +135,8 @@
 
   void createInitialThunkSections(ArrayRef<OutputSection *> OutputSections);
 
-  std::pair<Thunk *, bool> getThunk(Symbol &Sym, RelType Type, uint64_t Src);
+  std::pair<Thunk *, bool> getThunk(InputSection *IS, Symbol &Sym, RelType Type,
+                                    uint64_t Src);
 
   ThunkSection *addThunkSection(OutputSection *OS, InputSectionDescription *,
                                 uint64_t Off);
Index: lld/ELF/Relocations.cpp
===================================================================
--- lld/ELF/Relocations.cpp
+++ lld/ELF/Relocations.cpp
@@ -1604,12 +1604,13 @@
                                             InputSectionDescription *ISD,
                                             uint64_t Off) {
   auto *TS = make<ThunkSection>(OS, Off);
+  TS->Partition = OS->Partition;
   ISD->ThunkSections.push_back({TS, Pass});
   return TS;
 }
 
-std::pair<Thunk *, bool> ThunkCreator::getThunk(Symbol &Sym, RelType Type,
-                                                uint64_t Src) {
+std::pair<Thunk *, bool> ThunkCreator::getThunk(InputSection *IS, Symbol &Sym,
+                                                RelType Type, uint64_t Src) {
   std::vector<Thunk *> *ThunkVec = nullptr;
 
   // We use (section, offset) pair to find the thunk position if possible so
@@ -1622,7 +1623,8 @@
 
   // Check existing Thunks for Sym to see if they can be reused
   for (Thunk *T : *ThunkVec)
-    if (T->isCompatibleWith(Type) &&
+    if (T->getThunkTargetSym()->Section->Partition == IS->Partition &&
+        T->isCompatibleWith(Type) &&
         Target->inBranchRange(Type, Src, T->getThunkTargetSym()->getVA()))
       return std::make_pair(T, false);
 
@@ -1706,7 +1708,7 @@
 
             Thunk *T;
             bool IsNew;
-            std::tie(T, IsNew) = getThunk(*Rel.Sym, Rel.Type, Src);
+            std::tie(T, IsNew) = getThunk(IS, *Rel.Sym, Rel.Type, Src);
 
             if (IsNew) {
               // Find or create a ThunkSection for the new Thunk


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