[PATCH] D53003: [ELF] Fix link failure with Android compressed relocation support.

[Eli Friedman via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rLLD344300: [ELF] Fix link failure with Android compressed relocation support. (authored by efriedma, committed by ).

Changed prior to commit:
  https://reviews.llvm.org/D53003?vs=168721&id=169310#toc

Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D53003

Files:
  ELF/SyntheticSections.cpp
  test/ELF/pack-dyn-relocs-loop.s


Index: ELF/SyntheticSections.cpp
===================================================================
--- ELF/SyntheticSections.cpp
+++ ELF/SyntheticSections.cpp
@@ -1724,6 +1724,11 @@
     }
   }
 
+  // Don't allow the section to shrink; otherwise the size of the section can
+  // oscillate infinitely.
+  if (RelocData.size() < OldSize)
+    RelocData.append(OldSize - RelocData.size(), 0);
+
   // Returns whether the section size changed. We need to keep recomputing both
   // section layout and the contents of this section until the size converges
   // because changing this section's size can affect section layout, which in
Index: test/ELF/pack-dyn-relocs-loop.s
===================================================================
--- test/ELF/pack-dyn-relocs-loop.s
+++ test/ELF/pack-dyn-relocs-loop.s
@@ -0,0 +1,66 @@
+// REQUIRES: arm, aarch64
+
+// RUN: llvm-mc -filetype=obj -triple=aarch64-none-linux-android %s -o %t.o
+// RUN: ld.lld -shared %t.o -o %t.so --pack-dyn-relocs=android
+// RUN: llvm-readobj -s %t.so | FileCheck %s
+
+// This test is making sure the Android packed relocation support doesn't
+// cause an infinite loop due to the size of the section oscillating
+// (because the size of the section impacts the layout of the following
+// sections).
+
+// This test is very sensitive to the exact section sizes and offsets,
+// so check that they don't change.
+// CHECK:         Name: .rela.dyn (33)
+// CHECK-NEXT:    Type: SHT_ANDROID_RELA (0x60000002)
+// CHECK-NEXT:    Flags [ (0x2)
+// CHECK-NEXT:      SHF_ALLOC (0x2)
+// CHECK-NEXT:    ]
+// CHECK-NEXT:    Address: 0x210
+// CHECK-NEXT:    Offset: 0x210
+// CHECK-NEXT:    Size: 21
+
+// CHECK:         Name: x (43)
+// CHECK-NEXT:    Type: SHT_PROGBITS (0x1)
+// CHECK-NEXT:    Flags [ (0x2)
+// CHECK-NEXT:      SHF_ALLOC (0x2)
+// CHECK-NEXT:    ]
+// CHECK-NEXT:    Address: 0x225
+// CHECK-NEXT:    Offset: 0x225
+// CHECK-NEXT:    Size: 64980
+
+// CHECK:         Name: barr (45)
+// CHECK-NEXT:    Type: SHT_PROGBITS (0x1)
+// CHECK-NEXT:    Flags [ (0x2)
+// CHECK-NEXT:      SHF_ALLOC (0x2)
+// CHECK-NEXT:    ]
+// CHECK-NEXT:    Address: 0xFFFA
+// CHECK-NEXT:    Offset: 0xFFFA
+// CHECK-NEXT:    Size: 0
+
+// CHECK:         Name: foo (62)
+// CHECK-NEXT:    Type: SHT_PROGBITS (0x1)
+// CHECK-NEXT:    Flags [ (0x3)
+// CHECK-NEXT:      SHF_ALLOC (0x2)
+// CHECK-NEXT:      SHF_WRITE (0x1)
+// CHECK-NEXT:    ]
+// CHECK-NEXT:    Address: 0x10004
+// CHECK-NEXT:    Offset: 0x10004
+// CHECK-NEXT:    Size: 12
+
+
+.data
+.long 0
+
+.section foo,"aw"
+foof:
+.long foof
+.long bar-53
+.long bar
+
+.section x,"a"
+.zero 64980
+
+.section barr,"a"
+.p2align 1
+bar:


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