Add asserts and state tracking to ensure that we do not call

src/arm/regexp-macro-assembler-arm.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
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 //
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 //       disclaimer in the documentation and/or other materials provided
@@ skipping 353 matching lines @@
     __ add(r0, r0, Operand(end_of_input_address()));
     // Length of capture.
     __ mov(r2, Operand(r1));
     // Save length in callee-save register for use on return.
     __ mov(r4, Operand(r1));
     // Address of current input position.
     __ add(r1, current_input_offset(), Operand(end_of_input_address()));
     // Isolate.
     __ mov(r3, Operand(ExternalReference::isolate_address()));
 
-    ExternalReference function =
-        ExternalReference::re_case_insensitive_compare_uc16(masm_->isolate());
-    __ CallCFunction(function, argument_count);
+    {
+      // The compare function can't cause a GC.  Tell the system that it is OK
+      // to call into C++ without having a stack frame in place.
+      FrameScope scope(masm_, StackFrame::NONE);
+      ExternalReference function =
+          ExternalReference::re_case_insensitive_compare_uc16(masm_->isolate());
+      __ CallCFunction(function, argument_count);

[Søren Thygesen Gjesse, 2011/05/31 07:51:45]

How about having CallCFunctionWithoutFrame or CallCFunctionNotCausingGC instead?
Then the comment is not needed.

[Erik Corry, 2011/05/31 11:52:52]

This turns out to be messy because there are lots and lots of CallCFunction
variants.  Instead I introduced a new scoped variable called
AllowExternalCallThatCantCauseGC.  I am hoping with a name like that I don't
need a comment.

+    }
 
     // Check if function returned non-zero for success or zero for failure.
     __ cmp(r0, Operand(0, RelocInfo::NONE));
     BranchOrBacktrack(eq, on_no_match);
     // On success, increment position by length of capture.
     __ add(current_input_offset(), current_input_offset(), Operand(r4));
   }
 
   __ bind(&fallthrough);
 }
@@ skipping 217 matching lines @@
   __ jmp(&exit_label_);
 }
 
 
 Handle<HeapObject> RegExpMacroAssemblerARM::GetCode(Handle<String> source) {
   // Finalize code - write the entry point code now we know how many
   // registers we need.
 
   // Entry code:
   __ bind(&entry_label_);
+
+  // Tell the system that we have a stack frame.  Because the type is NONE, no
+  // is generated.
+  FrameScope scope(masm_, StackFrame::NONE);
+
+  // Actually emit code to start a new stack frame.
   // Push arguments
   // Save callee-save registers.
   // Start new stack frame.
   // Store link register in existing stack-cell.
   // Order here should correspond to order of offset constants in header file.
   RegList registers_to_retain = r4.bit() | r5.bit() | r6.bit() |
       r7.bit() | r8.bit() | r9.bit() | r10.bit() | fp.bit();
   RegList argument_registers = r0.bit() | r1.bit() | r2.bit() | r3.bit();
   __ stm(db_w, sp, argument_registers | registers_to_retain | lr.bit());
   // Set frame pointer in space for it if this is not a direct call
@@ skipping 654 matching lines @@
   __ ldr(pc, MemOperand(sp, stack_alignment, PostIndex));
 }
 
 #undef __
 
 #endif  // V8_INTERPRETED_REGEXP
 
 }}  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM