Catch non-string subject in RegExpExecStub.

src/arm/code-stubs-arm.cc

Index: src/arm/code-stubs-arm.cc
diff --git a/src/arm/code-stubs-arm.cc b/src/arm/code-stubs-arm.cc
index 9e6f7596e7fc60131cdaf956d07567854514e74b..a3dac34a4dbdfebcebae93404cd56f864dd0025c 100644
--- a/src/arm/code-stubs-arm.cc
+++ b/src/arm/code-stubs-arm.cc
@@ -4575,10 +4575,15 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
   Label cons_string, check_encoding;
   STATIC_ASSERT(kConsStringTag < kExternalStringTag);
   STATIC_ASSERT(kSlicedStringTag > kExternalStringTag);
+  STATIC_ASSERT(kIsNotStringMask > kExternalStringTag);
   __ cmp(r1, Operand(kExternalStringTag));
   __ b(lt, &cons_string);
   __ b(eq, &runtime);
 
+  // Catch non-string subject (should already have been guarded against).
+  __ tst(ebx, Immediate(kIsNotStringMask));

[Lasse Reichstein, 2011/11/24 09:31:57]

If it should have been guarded against, then make this an Assert check guarded
by FLAG_debug_code.
And if it there is actually a way to get here with a non-string, it should be
found and eliminated. We control the arguments to stubs completely, and are
expected to handle them safely.
If it's called from %_RegExpExec, then the test should be performed there (all
%-functions must check their arguments thoroughly).

+  __ b(eq, &runtime);
+
   // String is sliced.
   __ ldr(r9, FieldMemOperand(subject, SlicedString::kOffsetOffset));
   __ mov(r9, Operand(r9, ASR, kSmiTagSize));