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

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

Index: src/arm/regexp-macro-assembler-arm.cc
===================================================================
--- src/arm/regexp-macro-assembler-arm.cc	(revision 8110)
+++ src/arm/regexp-macro-assembler-arm.cc	(working copy)
@@ -371,9 +371,14 @@
     // 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));
@@ -611,6 +616,12 @@
 
   // 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.