Fix unaligned reads/writes in X86JIT and RuntimeDyldELF.

Summary:
Introduce support::ulittleX_t::ref type to Support/Endian.h and use it in x86 JIT
to enforce correct endianness and fix unaligned accesses.

Test Plan: regression test suite

Reviewers: lhames

Subscribers: ributzka, llvm-commits

Differential Revision: http://reviews.llvm.org/D5011

llvm-svn: 216631

1 files changed, 22 insertions, 26 deletions

diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
index 9aa04119724..adea5ad2241 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
@@ -23,6 +23,7 @@
 #include "llvm/Object/ELFObjectFile.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/ELF.h"
+#include "llvm/Support/Endian.h"
 #include "llvm/Support/MemoryBuffer.h"
 
 using namespace llvm;
@@ -260,10 +261,9 @@ void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
     llvm_unreachable("Relocation type not implemented yet!");
     break;
   case ELF::R_X86_64_64: {
-    uint64_t *Target = reinterpret_cast<uint64_t *>(Section.Address + Offset);
-    *Target = Value + Addend;
+    support::ulittle64_t::ref(Section.Address + Offset) = Value + Addend;
     DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
-                 << format("%p\n", Target));
+                 << format("%p\n", Section.Address + Offset));
     break;
   }
   case ELF::R_X86_64_32:
@@ -273,17 +273,15 @@ void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
            (Type == ELF::R_X86_64_32S &&
             ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
     uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
-    uint32_t *Target = reinterpret_cast<uint32_t *>(Section.Address + Offset);
-    *Target = TruncatedAddr;
+    support::ulittle32_t::ref(Section.Address + Offset) = TruncatedAddr;
     DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at "
-                 << format("%p\n", Target));
+                 << format("%p\n", Section.Address + Offset));
     break;
   }
   case ELF::R_X86_64_GOTPCREL: {
     // findGOTEntry returns the 'G + GOT' part of the relocation calculation
     // based on the load/target address of the GOT (not the current/local addr).
     uint64_t GOTAddr = findGOTEntry(Value, SymOffset);
-    uint32_t *Target = reinterpret_cast<uint32_t *>(Section.Address + Offset);
     uint64_t FinalAddress = Section.LoadAddress + Offset;
     // The processRelocationRef method combines the symbol offset and the addend
     // and in most cases that's what we want.  For this relocation type, we need
@@ -291,30 +289,29 @@ void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
     int64_t RealOffset = GOTAddr + Addend - SymOffset - FinalAddress;
     assert(RealOffset <= INT32_MAX && RealOffset >= INT32_MIN);
     int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
-    *Target = TruncOffset;
+    support::ulittle32_t::ref(Section.Address + Offset) = TruncOffset;
     break;
   }
   case ELF::R_X86_64_PC32: {
     // Get the placeholder value from the generated object since
     // a previous relocation attempt may have overwritten the loaded version
-    uint32_t *Placeholder =
-        reinterpret_cast<uint32_t *>(Section.ObjAddress + Offset);
-    uint32_t *Target = reinterpret_cast<uint32_t *>(Section.Address + Offset);
+    support::ulittle32_t::ref Placeholder(
+        (void *)(Section.ObjAddress + Offset));
     uint64_t FinalAddress = Section.LoadAddress + Offset;
-    int64_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
+    int64_t RealOffset = Placeholder + Value + Addend - FinalAddress;
     assert(RealOffset <= INT32_MAX && RealOffset >= INT32_MIN);
     int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
-    *Target = TruncOffset;
+    support::ulittle32_t::ref(Section.Address + Offset) = TruncOffset;
     break;
   }
   case ELF::R_X86_64_PC64: {
     // Get the placeholder value from the generated object since
     // a previous relocation attempt may have overwritten the loaded version
-    uint64_t *Placeholder =
-        reinterpret_cast<uint64_t *>(Section.ObjAddress + Offset);
-    uint64_t *Target = reinterpret_cast<uint64_t *>(Section.Address + Offset);
+    support::ulittle64_t::ref Placeholder(
+        (void *)(Section.ObjAddress + Offset));
     uint64_t FinalAddress = Section.LoadAddress + Offset;
-    *Target = *Placeholder + Value + Addend - FinalAddress;
+    support::ulittle64_t::ref(Section.Address + Offset) =
+        Placeholder + Value + Addend - FinalAddress;
     break;
   }
   }
@@ -327,21 +324,20 @@ void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
   case ELF::R_386_32: {
     // Get the placeholder value from the generated object since
     // a previous relocation attempt may have overwritten the loaded version
-    uint32_t *Placeholder =
-        reinterpret_cast<uint32_t *>(Section.ObjAddress + Offset);
-    uint32_t *Target = reinterpret_cast<uint32_t *>(Section.Address + Offset);
-    *Target = *Placeholder + Value + Addend;
+    support::ulittle32_t::ref Placeholder(
+        (void *)(Section.ObjAddress + Offset));
+    support::ulittle32_t::ref(Section.Address + Offset) =
+        Placeholder + Value + Addend;
     break;
   }
   case ELF::R_386_PC32: {
     // Get the placeholder value from the generated object since
     // a previous relocation attempt may have overwritten the loaded version
-    uint32_t *Placeholder =
-        reinterpret_cast<uint32_t *>(Section.ObjAddress + Offset);
-    uint32_t *Target = reinterpret_cast<uint32_t *>(Section.Address + Offset);
+    support::ulittle32_t::ref Placeholder(
+        (void *)(Section.ObjAddress + Offset));
     uint32_t FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
-    uint32_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
-    *Target = RealOffset;
+    uint32_t RealOffset = Placeholder + Value + Addend - FinalAddress;
+    support::ulittle32_t::ref(Section.Address + Offset) = RealOffset;
     break;
   }
   default: