[turbofan] Allow unittest to call TruncateDoubleToI.

src/arm64/macro-assembler-arm64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 2995 matching lines @@
   Cmp(result.X(), 1);
   Ccmp(result.X(), -1, VFlag, vc);
 
   B(vc, done);
 }
 
 
 void MacroAssembler::TruncateDoubleToI(Register result,
                                        DoubleRegister double_input) {
   Label done;
-  DCHECK(jssp.Is(StackPointer()));
 
   // Try to convert the double to an int64. If successful, the bottom 32 bits
   // contain our truncated int32 result.
   TryConvertDoubleToInt64(result, double_input, &done);
 
+  const Register old_stack_pointer = StackPointer();
+  if (csp.Is(old_stack_pointer)) {
+    // This currently only happens during compiler-unittest. If it arises
+    // during regular code generation the DoubleToI stub should be updated to
+    // cope with csp and have an extra parameter indicating which stack pointer
+    // it should use.
+    Push(jssp, xzr);  // Push xzr to maintain csp required 16-bytes alignment.
+    Mov(jssp, csp);
+    SetStackPointer(jssp);
+  }
+
   // If we fell through then inline version didn't succeed - call stub instead.
   Push(lr, double_input);
 
   DoubleToIStub stub(isolate(),
                      jssp,
                      result,
                      0,
                      true,   // is_truncating
                      true);  // skip_fastpath
   CallStub(&stub);  // DoubleToIStub preserves any registers it needs to clobber
 
-  Drop(1, kDoubleSize);  // Drop the double input on the stack.
-  Pop(lr);
+  DCHECK_EQ(xzr.SizeInBytes(), double_input.SizeInBytes());
+  Pop(xzr, lr);  // xzr to drop the double input on the stack.
+
+  if (csp.Is(old_stack_pointer)) {
+    Mov(csp, jssp);
+    SetStackPointer(csp);
+    AssertStackConsistency();
+    Pop(xzr, jssp);
+  }
 
   Bind(&done);
 }
 
 
 void MacroAssembler::TruncateHeapNumberToI(Register result,
                                            Register object) {
   Label done;
   DCHECK(!result.is(object));
   DCHECK(jssp.Is(StackPointer()));
@@ skipping 2363 matching lines @@
   }
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64