[llvm] 386f1c1 - [Object] Remove conditional layout of bitfields in MachO::relocation_info.

[Lang Hames via llvm-commits]

Author: Lang Hames
Date: 2020-04-16T16:17:36-07:00
New Revision: 386f1c114d5952c13760cb3368d41d09d8ba099c

URL: https://github.com/llvm/llvm-project/commit/386f1c114d5952c13760cb3368d41d09d8ba099c
DIFF: https://github.com/llvm/llvm-project/commit/386f1c114d5952c13760cb3368d41d09d8ba099c.diff

LOG: [Object] Remove conditional layout of bitfields in MachO::relocation_info.

This removes the conditional layout of relocation_info bitfields that was
introduced in 3ccd677bf (svn r358839). The platform relocation_info
struct (defined in usr/include/mach-o/reloc.h) does not define the layout of
this struct differently on big-endian platforms and we want to keep the LLVM
and platform definitions in sync.

To fix the bug that 3ccd677bf addressed this patch modifies JITLink to construct
its relocation_info structs from the raw relocation words using shift and mask
operations.

Added: 
    

Modified: 
    llvm/include/llvm/BinaryFormat/MachO.h
    llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
    llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
    llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/BinaryFormat/MachO.h b/llvm/include/llvm/BinaryFormat/MachO.h
index 53959182e987..0010f36e8b89 100644
--- a/llvm/include/llvm/BinaryFormat/MachO.h
+++ b/llvm/include/llvm/BinaryFormat/MachO.h
@@ -952,13 +952,8 @@ struct fat_arch_64 {
 // Structs from <mach-o/reloc.h>
 struct relocation_info {
   int32_t r_address;
-#if defined(BYTE_ORDER) && defined(BIG_ENDIAN) && (BYTE_ORDER == BIG_ENDIAN)
-  uint32_t r_type : 4,  r_extern : 1, r_length : 2, r_pcrel : 1,
-      r_symbolnum : 24;
-#else
   uint32_t r_symbolnum : 24, r_pcrel : 1, r_length : 2, r_extern : 1,
       r_type : 4;
-#endif
 };
 
 struct scattered_relocation_info {

diff  --git a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
index 06d4787fc43c..ffe010054ff5 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
+++ b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
@@ -153,6 +153,20 @@ class MachOLinkGraphBuilder {
   static Scope getScope(StringRef Name, uint8_t Type);
   static bool isAltEntry(const NormalizedSymbol &NSym);
 
+  MachO::relocation_info
+  getRelocationInfo(const object::relocation_iterator RelItr) {
+    MachO::any_relocation_info ARI =
+        getObject().getRelocation(RelItr->getRawDataRefImpl());
+    MachO::relocation_info RI;
+    RI.r_address = ARI.r_word0;
+    RI.r_symbolnum = ARI.r_word1 & 0xffffff;
+    RI.r_pcrel = (ARI.r_word1 >> 24) & 1;
+    RI.r_length = (ARI.r_word1 >> 25) & 3;
+    RI.r_extern = (ARI.r_word1 >> 27) & 1;
+    RI.r_type = (ARI.r_word1 >> 28);
+    return RI;
+  }
+
 private:
   static unsigned getPointerSize(const object::MachOObjectFile &Obj);
   static support::endianness getEndianness(const object::MachOObjectFile &Obj);

diff  --git a/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp b/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
index cc3940393bfc..55c7b36142a0 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
@@ -92,15 +92,6 @@ class MachOLinkGraphBuilder_arm64 : public MachOLinkGraphBuilder {
         ", length=" + formatv("{0:d}", RI.r_length));
   }
 
-  MachO::relocation_info
-  getRelocationInfo(const object::relocation_iterator RelItr) {
-    MachO::any_relocation_info ARI =
-        getObject().getRelocation(RelItr->getRawDataRefImpl());
-    MachO::relocation_info RI;
-    memcpy(&RI, &ARI, sizeof(MachO::relocation_info));
-    return RI;
-  }
-
   using PairRelocInfo =
       std::tuple<MachOARM64RelocationKind, Symbol *, uint64_t>;
 

diff  --git a/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp b/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
index 05e323b18d80..9abeddfb1920 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
@@ -95,15 +95,6 @@ class MachOLinkGraphBuilder_x86_64 : public MachOLinkGraphBuilder {
         ", length=" + formatv("{0:d}", RI.r_length));
   }
 
-  MachO::relocation_info
-  getRelocationInfo(const object::relocation_iterator RelItr) {
-    MachO::any_relocation_info ARI =
-        getObject().getRelocation(RelItr->getRawDataRefImpl());
-    MachO::relocation_info RI;
-    memcpy(&RI, &ARI, sizeof(MachO::relocation_info));
-    return RI;
-  }
-
   using PairRelocInfo = std::tuple<MachOX86RelocationKind, Symbol *, uint64_t>;
 
   // Parses paired SUBTRACTOR/UNSIGNED relocations and, on success,