[lld] r349216 - ELF: Handle R_ARM_V4BX correctly in PIC output files.

[Peter Collingbourne via llvm-commits]

Author: pcc
Date: Fri Dec 14 16:20:17 2018
New Revision: 349216

URL: http://llvm.org/viewvc/llvm-project?rev=349216&view=rev
Log:
ELF: Handle R_ARM_V4BX correctly in PIC output files.

Previously we considered R_ARM_V4BX to be an absolute relocation,
which meant that we rejected it in read-only sections in PIC output
files. Instead, treat it as a hint relocation so that relocation
processing ignores it entirely.

Also fix a problem with the test case where it was never being run
because it has a .yaml extension and we don't run tests with that
extension.

Differential Revision: https://reviews.llvm.org/D55728

Added:
    lld/trunk/test/ELF/arm-v4bx.test
Removed:
    lld/trunk/test/ELF/v4bx.yaml
Modified:
    lld/trunk/ELF/Arch/ARM.cpp

Modified: lld/trunk/ELF/Arch/ARM.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Arch/ARM.cpp?rev=349216&r1=349215&r2=349216&view=diff
==============================================================================
--- lld/trunk/ELF/Arch/ARM.cpp (original)
+++ lld/trunk/ELF/Arch/ARM.cpp Fri Dec 14 16:20:17 2018
@@ -134,6 +134,12 @@ RelExpr ARM::getRelExpr(RelType Type, co
     return R_NONE;
   case R_ARM_TLS_LE32:
     return R_TLS;
+  case R_ARM_V4BX:
+    // V4BX is just a marker to indicate there's a "bx rN" instruction at the
+    // given address. It can be used to implement a special linker mode which
+    // rewrites ARMv4T inputs to ARMv4. Since we support only ARMv4 input and
+    // not ARMv4 output, we can just ignore it.
+    return R_HINT;
   default:
     return R_ABS;
   }
@@ -514,12 +520,6 @@ void ARM::relocateOne(uint8_t *Loc, RelT
                   ((Val << 4) & 0x7000) |    // imm3
                   (Val & 0x00ff));           // imm8
     break;
-  case R_ARM_V4BX:
-    // V4BX is just a marker to indicate there's a "bx rN" instruction at the
-    // given address. It can be used to implement a special linker mode which
-    // rewrites ARMv4T inputs to ARMv4. Since we support only ARMv4 input and
-    // not ARMv4 output, we can just ignore it.
-    break;
   default:
     error(getErrorLocation(Loc) + "unrecognized reloc " + Twine(Type));
   }

Added: lld/trunk/test/ELF/arm-v4bx.test
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/arm-v4bx.test?rev=349216&view=auto
==============================================================================
--- lld/trunk/test/ELF/arm-v4bx.test (added)
+++ lld/trunk/test/ELF/arm-v4bx.test Fri Dec 14 16:20:17 2018
@@ -0,0 +1,40 @@
+# REQUIRES: arm
+# RUN: yaml2obj %s -o %t.o
+# RUN: ld.lld %t.o -o %t
+# RUN: llvm-readelf -sections %t | FileCheck %s
+# RUN: ld.lld -shared %t.o -o %t
+# RUN: llvm-readelf -sections %t | FileCheck %s
+
+# CHECK: .text
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS32
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_ARM
+  Flags:           [ EF_ARM_EABI_VER5 ]
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x0000000000000004
+    Content:         1EFF2F01
+  - Name:            .rel.text
+    Type:            SHT_REL
+    Link:            .symtab
+    AddressAlign:    0x0000000000000004
+    Info:            .text
+    Relocations:
+      - Offset:          0x0000000000000000
+        Symbol:          ''
+        Type:            R_ARM_V4BX
+Symbols:
+  Global:
+    - Name:            _start
+      Section:         .text
+  Local:
+    - Name:            .text
+      Type:            STT_SECTION
+      Section:         .text
+DynamicSymbols:

Removed: lld/trunk/test/ELF/v4bx.yaml
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/v4bx.yaml?rev=349215&view=auto
==============================================================================
--- lld/trunk/test/ELF/v4bx.yaml (original)
+++ lld/trunk/test/ELF/v4bx.yaml (removed)
@@ -1,38 +0,0 @@
-# REQUIRES: arm
-# RUN: yaml2obj %s -o %t.o
-# RUN: ld.lld %t.o -o %t
-# RUN: llvm-readelf -sections %t | FileCheck %s
-
-# CHECK: .text
-
---- !ELF
-FileHeader:
-  Class:           ELFCLASS32
-  Data:            ELFDATA2LSB
-  Type:            ET_REL
-  Machine:         EM_ARM
-  Flags:           [ EF_ARM_EABI_VER5 ]
-Sections:
-  - Name:            .text
-    Type:            SHT_PROGBITS
-    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
-    AddressAlign:    0x0000000000000004
-    Content:         1EFF2F01
-  - Name:            .rel.text
-    Type:            SHT_REL
-    Link:            .symtab
-    AddressAlign:    0x0000000000000004
-    Info:            .text
-    Relocations:
-      - Offset:          0x0000000000000000
-        Symbol:          ''
-        Type:            R_ARM_V4BX
-Symbols:
-  Global:
-    - Name:            _start
-      Section:         .text
-  Local:
-    - Name:            .text
-      Type:            STT_SECTION
-      Section:         .text
-DynamicSymbols: