Allow compiling with strict aliasing enabled on GCC 4.4.

Patch by Jay Freeman.
Fixes issue 463.

Review URL: http://codereview.chromium.org/3117007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5237 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

SConstruct

@@ -58,7 +58,7 @@ else:
 # on linux we need these compiler flags to avoid crashes in the v8 test suite
 # and avoid dtoa.c strict aliasing issues
 if os.environ.get('GCC_VERSION') == '44':
-    GCC_EXTRA_CCFLAGS = ['-fno-tree-vrp', '-fno-strict-aliasing']
+    GCC_EXTRA_CCFLAGS = ['-fno-tree-vrp']
     GCC_DTOA_EXTRA_CCFLAGS = []
 else:
     GCC_EXTRA_CCFLAGS = []
@@ -80,7 +80,6 @@ ANDROID_FLAGS = ['-march=armv7-a',
                  '-frerun-cse-after-loop',
                  '-frename-registers',
                  '-fomit-frame-pointer',
-                 '-fno-strict-aliasing',
                  '-finline-limit=64',
                  '-DCAN_USE_VFP_INSTRUCTIONS=1',
                  '-DCAN_USE_ARMV7_INSTRUCTIONS=1',

src/bootstrapper.cc

@@ -56,7 +56,7 @@ class SourceCodeCache BASE_EMBEDDED {
   }
 
   void Iterate(ObjectVisitor* v) {
-    v->VisitPointer(BitCast<Object**, FixedArray**>(&cache_));
+    v->VisitPointer(BitCast<Object**>(&cache_));
   }
 
 

src/debug.cc

@@ -852,8 +852,8 @@ void Debug::PreemptionWhileInDebugger() {
 
 
 void Debug::Iterate(ObjectVisitor* v) {
-  v->VisitPointer(BitCast<Object**, Code**>(&(debug_break_return_)));
-  v->VisitPointer(BitCast<Object**, Code**>(&(debug_break_slot_)));
+  v->VisitPointer(BitCast<Object**>(&(debug_break_return_)));
+  v->VisitPointer(BitCast<Object**>(&(debug_break_slot_)));
 }
 
 

src/factory.h

@@ -329,7 +329,7 @@ class Factory : public AllStatic {
 
 #define ROOT_ACCESSOR(type, name, camel_name)                                  \
   static inline Handle<type> name() {                                          \
-    return Handle<type>(BitCast<type**, Object**>(                             \
+    return Handle<type>(BitCast<type**>(                                       \
         &Heap::roots_[Heap::k##camel_name##RootIndex]));                       \
   }
   ROOT_LIST(ROOT_ACCESSOR)
@@ -337,7 +337,7 @@ class Factory : public AllStatic {
 
 #define SYMBOL_ACCESSOR(name, str) \
   static inline Handle<String> name() {                                        \
-    return Handle<String>(BitCast<String**, Object**>(                         \
+    return Handle<String>(BitCast<String**>(                                   \
         &Heap::roots_[Heap::k##name##RootIndex]));                             \
   }
   SYMBOL_LIST(SYMBOL_ACCESSOR)

src/heap.cc

@@ -4024,7 +4024,7 @@ void Heap::IterateStrongRoots(ObjectVisitor* v, VisitMode mode) {
   v->VisitPointers(&roots_[0], &roots_[kStrongRootListLength]);
   v->Synchronize("strong_root_list");
 
-  v->VisitPointer(BitCast<Object**, String**>(&hidden_symbol_));
+  v->VisitPointer(BitCast<Object**>(&hidden_symbol_));
   v->Synchronize("symbol");
 
   Bootstrapper::Iterate(v);

src/mips/simulator-mips.cc

@@ -606,7 +606,7 @@ void Simulator::set_fpu_register(int fpureg, int32_t value) {
 
 void Simulator::set_fpu_register_double(int fpureg, double value) {
   ASSERT((fpureg >= 0) && (fpureg < kNumFPURegisters) && ((fpureg % 2) == 0));
-  *v8i::BitCast<double*, int32_t*>(&FPUregisters_[fpureg]) = value;
+  *v8i::BitCast<double*>(&FPUregisters_[fpureg]) = value;
 }
 
 
@@ -627,8 +627,7 @@ int32_t Simulator::get_fpu_register(int fpureg) const {
 
 double Simulator::get_fpu_register_double(int fpureg) const {
   ASSERT((fpureg >= 0) && (fpureg < kNumFPURegisters) && ((fpureg % 2) == 0));
-  return *v8i::BitCast<double*, int32_t*>(
-      const_cast<int32_t*>(&FPUregisters_[fpureg]));
+  return *v8i::BitCast<double*>(const_cast<int32_t*>(&FPUregisters_[fpureg]));
 }
 
 // Raw access to the PC register.
@@ -903,7 +902,7 @@ void Simulator::DecodeTypeRegister(Instruction* instr) {
           break;
         case MFHC1:
           fp_out = get_fpu_register_double(fs_reg);
-          alu_out = *v8i::BitCast<int32_t*, double*>(&fp_out);
+          alu_out = *v8i::BitCast<int32_t*>(&fp_out);
           break;
         case MTC1:
         case MTHC1:

src/top.cc

@@ -107,16 +107,15 @@ void Top::IterateThread(ThreadVisitor* v, char* t) {
 void Top::Iterate(ObjectVisitor* v, ThreadLocalTop* thread) {
   v->VisitPointer(&(thread->pending_exception_));
   v->VisitPointer(&(thread->pending_message_obj_));
-  v->VisitPointer(
-      BitCast<Object**, Script**>(&(thread->pending_message_script_)));
-  v->VisitPointer(BitCast<Object**, Context**>(&(thread->context_)));
+  v->VisitPointer(BitCast<Object**>(&(thread->pending_message_script_)));
+  v->VisitPointer(BitCast<Object**>(&(thread->context_)));
   v->VisitPointer(&(thread->scheduled_exception_));
 
   for (v8::TryCatch* block = thread->TryCatchHandler();
        block != NULL;
        block = TRY_CATCH_FROM_ADDRESS(block->next_)) {
-    v->VisitPointer(BitCast<Object**, void**>(&(block->exception_)));
-    v->VisitPointer(BitCast<Object**, void**>(&(block->message_)));
+    v->VisitPointer(BitCast<Object**>(&(block->exception_)));
+    v->VisitPointer(BitCast<Object**>(&(block->message_)));
   }
 
   // Iterate over pointers on native execution stack.

src/utils.h

@@ -739,7 +739,11 @@ inline Dest BitCast(const Source& source) {
   return dest;
 }
 
-} }  // namespace v8::internal
+template <class Dest, class Source>
+inline Dest BitCast(Source* const & source) {
+    return BitCast<Dest>(reinterpret_cast<uintptr_t>(source));
+}
 
+} }  // namespace v8::internal
 
 #endif  // V8_UTILS_H_

src/x64/assembler-x64.cc

@@ -253,7 +253,7 @@ Operand::Operand(const Operand& operand, int32_t offset) {
   int32_t disp_value = 0;
   if (mode == 0x80 || is_baseless) {
     // Mode 2 or mode 0 with rbp/r13 as base: Word displacement.
-    disp_value = *reinterpret_cast<const int32_t*>(&operand.buf_[disp_offset]);
+    disp_value = *BitCast<const int32_t*>(&operand.buf_[disp_offset]);
   } else if (mode == 0x40) {
     // Mode 1: Byte displacement.
     disp_value = static_cast<signed char>(operand.buf_[disp_offset]);

tools/gyp/v8.gyp

@@ -108,8 +108,6 @@
             'conditions': [
               [ 'gcc_version==44', {
                 'cflags': [
-                  # Avoid gcc 4.4 strict aliasing issues in dtoa.c
-                  '-fno-strict-aliasing',
                   # Avoid crashes with gcc 4.4 in the v8 test suite.
                   '-fno-tree-vrp',
                 ],