[arm64] Add assertions to Claim and Drop.

In particular, Claim doesn't work with a negative size, so ensure that
it is positive.

BUG=

Review URL: https://codereview.chromium.org/1565193002

Cr-Commit-Position: refs/heads/master@{#33198}

src/arm64/macro-assembler-arm64-inl.h

@@ -1462,7 +1462,8 @@ void MacroAssembler::Push(Handle<Object> handle) {
 }
 
 
-void MacroAssembler::Claim(uint64_t count, uint64_t unit_size) {
+void MacroAssembler::Claim(int64_t count, uint64_t unit_size) {
+  DCHECK(count >= 0);
   uint64_t size = count * unit_size;
 
   if (size == 0) {
@@ -1490,6 +1491,7 @@ void MacroAssembler::Claim(const Register& count, uint64_t unit_size) {
     return;
   }
 
+  AssertPositiveOrZero(count);
   if (!csp.Is(StackPointer())) {
     BumpSystemStackPointer(size);
   }
@@ -1517,7 +1519,8 @@ void MacroAssembler::ClaimBySMI(const Register& count_smi, uint64_t unit_size) {
 }
 
 
-void MacroAssembler::Drop(uint64_t count, uint64_t unit_size) {
+void MacroAssembler::Drop(int64_t count, uint64_t unit_size) {
+  DCHECK(count >= 0);
   uint64_t size = count * unit_size;
 
   if (size == 0) {
@@ -1548,6 +1551,7 @@ void MacroAssembler::Drop(const Register& count, uint64_t unit_size) {
     return;
   }
 
+  AssertPositiveOrZero(count);
   Add(StackPointer(), StackPointer(), size);
 
   if (!csp.Is(StackPointer()) && emit_debug_code()) {

src/arm64/macro-assembler-arm64.cc

@@ -1669,6 +1669,17 @@ void MacroAssembler::AssertString(Register object) {
 }
 
 
+void MacroAssembler::AssertPositiveOrZero(Register value) {
+  if (emit_debug_code()) {
+    Label done;
+    int sign_bit = value.Is64Bits() ? kXSignBit : kWSignBit;
+    Tbz(value, sign_bit, &done);
+    Abort(kUnexpectedNegativeValue);
+    Bind(&done);
+  }
+}
+
+
 void MacroAssembler::CallStub(CodeStub* stub, TypeFeedbackId ast_id) {
   DCHECK(AllowThisStubCall(stub));  // Stub calls are not allowed in some stubs.
   Call(stub->GetCode(), RelocInfo::CODE_TARGET, ast_id);

src/arm64/macro-assembler-arm64.h

@@ -724,10 +724,10 @@ class MacroAssembler : public Assembler {
   //
   // Note that unit_size must be specified in bytes. For variants which take a
   // Register count, the unit size must be a power of two.
-  inline void Claim(uint64_t count, uint64_t unit_size = kXRegSize);
+  inline void Claim(int64_t count, uint64_t unit_size = kXRegSize);
   inline void Claim(const Register& count,
                     uint64_t unit_size = kXRegSize);
-  inline void Drop(uint64_t count, uint64_t unit_size = kXRegSize);
+  inline void Drop(int64_t count, uint64_t unit_size = kXRegSize);
   inline void Drop(const Register& count,
                    uint64_t unit_size = kXRegSize);
 
@@ -977,6 +977,10 @@ class MacroAssembler : public Assembler {
   // Abort execution if argument is not a string, enabled via --debug-code.
   void AssertString(Register object);
 
+  // Abort execution if argument is not a positive or zero integer, enabled via
+  // --debug-code.
+  void AssertPositiveOrZero(Register value);
+
   void JumpIfHeapNumber(Register object, Label* on_heap_number,
                         SmiCheckType smi_check_type = DONT_DO_SMI_CHECK);
   void JumpIfNotHeapNumber(Register object, Label* on_not_heap_number,