[Deopt] Always patch deopted code to fail hard if entered.

Remove the --zap_code_space flag and always patch deopted code to hard fail
if called.

Also, as a drive-by add deopt code patching for Arm64.

BUG=v8:6246

Change-Id: Ibf1bc53692dbbe618132100a66c56a88c97fd62b
Reviewed-on: https://chromium-review.googlesource.com/496127Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45082}

include/v8.h

@@ -6220,9 +6220,8 @@ class V8_EXPORT HeapStatistics {
   size_t peak_malloced_memory() { return peak_malloced_memory_; }
 
   /**
-   * Returns a 0/1 boolean, which signifies whether the |--zap_code_space|
-   * option is enabled or not, which makes V8 overwrite heap garbage with a bit
-   * pattern.
+   * Returns a 0/1 boolean, which signifies whether the V8 overwrite heap
+   * garbage with a bit pattern.
    */
   size_t does_zap_garbage() { return does_zap_garbage_; }
 

src/arm/deoptimizer-arm.cc

@@ -34,7 +34,6 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
   // code patching below, and is not needed any more.
   code->InvalidateRelocation();
 
-  if (FLAG_zap_code_space) {
   // Fail hard and early if we enter this code object again.
   byte* pointer = code->FindCodeAgeSequence();
   if (pointer != NULL) {
@@ -54,11 +53,10 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
   int osr_offset = data->OsrPcOffset()->value();
   if (osr_offset > 0) {
     PatchingAssembler patcher(Assembler::IsolateData(isolate),
-                                code->instruction_start() + osr_offset, 1);
+                              code_start_address + osr_offset, 1);
     patcher.bkpt(0);
     patcher.FlushICache(isolate);
   }
-  }
 
   DeoptimizationInputData* deopt_data =
       DeoptimizationInputData::cast(code->deoptimization_data());

src/arm64/deoptimizer-arm64.cc

@@ -31,16 +31,35 @@ void Deoptimizer::EnsureRelocSpaceForLazyDeoptimization(Handle<Code> code) {
 
 
 void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
+  Address code_start_address = code->instruction_start();
   // Invalidate the relocation information, as it will become invalid by the
   // code patching below, and is not needed any more.
   code->InvalidateRelocation();
 
-  // TODO(jkummerow): if (FLAG_zap_code_space), make the code object's
-  // entry sequence unusable (see other architectures).
+  // Fail hard and early if we enter this code object again.
+  byte* pointer = code->FindCodeAgeSequence();
+  if (pointer != NULL) {
+    pointer += kNoCodeAgeSequenceLength;
+  } else {
+    pointer = code->instruction_start();
+  }
+
+  {
+    PatchingAssembler patcher(Assembler::IsolateData(isolate), pointer, 1);
+    patcher.brk(0);
+  }
+
+  DeoptimizationInputData* data =
+      DeoptimizationInputData::cast(code->deoptimization_data());
+  int osr_offset = data->OsrPcOffset()->value();
+  if (osr_offset > 0) {
+    PatchingAssembler patcher(Assembler::IsolateData(isolate),
+                              code_start_address + osr_offset, 1);
+    patcher.brk(0);
+  }
 
   DeoptimizationInputData* deopt_data =
       DeoptimizationInputData::cast(code->deoptimization_data());
-  Address code_start_address = code->instruction_start();
 #ifdef DEBUG
   Address prev_call_address = NULL;
 #endif

src/flag-definitions.h

@@ -716,8 +716,6 @@ DEFINE_BOOL(cleanup_code_caches_at_gc, true,
 DEFINE_BOOL(use_marking_progress_bar, true,
             "Use a progress bar to scan large objects in increments when "
             "incremental marking is active.")
-DEFINE_BOOL(zap_code_space, DEBUG_BOOL,
-            "Zap free memory in code space with 0xCC while sweeping.")
 DEFINE_BOOL(force_marking_deque_overflows, false,
             "force overflows of marking deque by reducing it's size "
             "to 64 words")

src/ia32/deoptimizer-ia32.cc

@@ -94,7 +94,6 @@ void Deoptimizer::EnsureRelocSpaceForLazyDeoptimization(Handle<Code> code) {
 void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
   Address code_start_address = code->instruction_start();
 
-  if (FLAG_zap_code_space) {
   // Fail hard and early if we enter this code object again.
   byte* pointer = code->FindCodeAgeSequence();
   if (pointer != NULL) {
@@ -109,11 +108,9 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
       DeoptimizationInputData::cast(code->deoptimization_data());
   int osr_offset = data->OsrPcOffset()->value();
   if (osr_offset > 0) {
-      CodePatcher osr_patcher(isolate, code->instruction_start() + osr_offset,
-                              1);
+    CodePatcher osr_patcher(isolate, code_start_address + osr_offset, 1);
     osr_patcher.masm()->int3();
   }
-  }
 
   // We will overwrite the code's relocation info in-place. Relocation info
   // is written backward. The relocation info is the payload of a byte

src/mips/deoptimizer-mips.cc

@@ -30,7 +30,6 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
   // code patching below, and is not needed any more.
   code->InvalidateRelocation();
 
-  if (FLAG_zap_code_space) {
   // Fail hard and early if we enter this code object again.
   byte* pointer = code->FindCodeAgeSequence();
   if (pointer != NULL) {
@@ -45,11 +44,9 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
       DeoptimizationInputData::cast(code->deoptimization_data());
   int osr_offset = data->OsrPcOffset()->value();
   if (osr_offset > 0) {
-      CodePatcher osr_patcher(isolate, code->instruction_start() + osr_offset,
-                              1);
+    CodePatcher osr_patcher(isolate, code_start_address + osr_offset, 1);
     osr_patcher.masm()->break_(0xCC);
   }
-  }
 
   DeoptimizationInputData* deopt_data =
       DeoptimizationInputData::cast(code->deoptimization_data());

src/mips64/deoptimizer-mips64.cc

@@ -30,7 +30,6 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
   // code patching below, and is not needed any more.
   code->InvalidateRelocation();
 
-  if (FLAG_zap_code_space) {
   // Fail hard and early if we enter this code object again.
   byte* pointer = code->FindCodeAgeSequence();
   if (pointer != NULL) {
@@ -45,11 +44,9 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
       DeoptimizationInputData::cast(code->deoptimization_data());
   int osr_offset = data->OsrPcOffset()->value();
   if (osr_offset > 0) {
-      CodePatcher osr_patcher(isolate, code->instruction_start() + osr_offset,
-                              1);
+    CodePatcher osr_patcher(isolate, code_start_address + osr_offset, 1);
     osr_patcher.masm()->break_(0xCC);
   }
-  }
 
   DeoptimizationInputData* deopt_data =
       DeoptimizationInputData::cast(code->deoptimization_data());

src/ppc/deoptimizer-ppc.cc

@@ -37,7 +37,6 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
   // code patching below, and is not needed any more.
   code->InvalidateRelocation();
 
-  if (FLAG_zap_code_space) {
   // Fail hard and early if we enter this code object again.
   byte* pointer = code->FindCodeAgeSequence();
   if (pointer != NULL) {
@@ -52,11 +51,9 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
       DeoptimizationInputData::cast(code->deoptimization_data());
   int osr_offset = data->OsrPcOffset()->value();
   if (osr_offset > 0) {
-      CodePatcher osr_patcher(isolate, code->instruction_start() + osr_offset,
-                              1);
+    CodePatcher osr_patcher(isolate, code_start_address + osr_offset, 1);
     osr_patcher.masm()->bkpt(0);
   }
-  }
 
   DeoptimizationInputData* deopt_data =
       DeoptimizationInputData::cast(code->deoptimization_data());

src/s390/deoptimizer-s390.cc

@@ -35,7 +35,6 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
   // code patching below, and is not needed any more.
   code->InvalidateRelocation();
 
-  if (FLAG_zap_code_space) {
   // Fail hard and early if we enter this code object again.
   byte* pointer = code->FindCodeAgeSequence();
   if (pointer != NULL) {
@@ -50,11 +49,9 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
       DeoptimizationInputData::cast(code->deoptimization_data());
   int osr_offset = data->OsrPcOffset()->value();
   if (osr_offset > 0) {
-      CodePatcher osr_patcher(isolate, code->instruction_start() + osr_offset,
-                              2);
+    CodePatcher osr_patcher(isolate, code_start_address + osr_offset, 2);
     osr_patcher.masm()->bkpt(0);
   }
-  }
 
   DeoptimizationInputData* deopt_data =
       DeoptimizationInputData::cast(code->deoptimization_data());

src/x64/deoptimizer-x64.cc

@@ -30,11 +30,11 @@ void Deoptimizer::EnsureRelocSpaceForLazyDeoptimization(Handle<Code> code) {
 
 
 void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
+  Address instruction_start = code->instruction_start();
   // Invalidate the relocation information, as it will become invalid by the
   // code patching below, and is not needed any more.
   code->InvalidateRelocation();
 
-  if (FLAG_zap_code_space) {
   // Fail hard and early if we enter this code object again.
   byte* pointer = code->FindCodeAgeSequence();
   if (pointer != NULL) {
@@ -49,11 +49,9 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
       DeoptimizationInputData::cast(code->deoptimization_data());
   int osr_offset = data->OsrPcOffset()->value();
   if (osr_offset > 0) {
-      CodePatcher osr_patcher(isolate, code->instruction_start() + osr_offset,
-                              1);
+    CodePatcher osr_patcher(isolate, instruction_start + osr_offset, 1);
     osr_patcher.masm()->int3();
   }
-  }
 
   // For each LLazyBailout instruction insert a absolute call to the
   // corresponding deoptimization entry, or a short call to an absolute
@@ -61,7 +59,6 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
   // before the safepoint table (space was allocated there when the Code
   // object was created, if necessary).
 
-  Address instruction_start = code->instruction_start();
 #ifdef DEBUG
   Address prev_call_address = NULL;
 #endif

src/x87/deoptimizer-x87.cc

@@ -94,7 +94,6 @@ void Deoptimizer::EnsureRelocSpaceForLazyDeoptimization(Handle<Code> code) {
 void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
   Address code_start_address = code->instruction_start();
 
-  if (FLAG_zap_code_space) {
   // Fail hard and early if we enter this code object again.
   byte* pointer = code->FindCodeAgeSequence();
   if (pointer != NULL) {
@@ -109,11 +108,9 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
       DeoptimizationInputData::cast(code->deoptimization_data());
   int osr_offset = data->OsrPcOffset()->value();
   if (osr_offset > 0) {
-      CodePatcher osr_patcher(isolate, code->instruction_start() + osr_offset,
-                              1);
+    CodePatcher osr_patcher(isolate, code_start_address + osr_offset, 1);
     osr_patcher.masm()->int3();
   }
-  }
 
   // We will overwrite the code's relocation info in-place. Relocation info
   // is written backward. The relocation info is the payload of a byte