MIPS: port Generated code for substring slices in x64 and arm.

Ported r9111 (2b946464)

BUG=
TEST=

Review URL: http://codereview.chromium.org/7835025

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9127 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/macro-assembler-mips.cc

@@ -2815,6 +2815,46 @@ void MacroAssembler::AllocateAsciiConsString(Register result,
 }
 
 
+void MacroAssembler::AllocateTwoByteSlicedString(Register result,
+                                                 Register length,
+                                                 Register scratch1,
+                                                 Register scratch2,
+                                                 Label* gc_required) {
+  AllocateInNewSpace(SlicedString::kSize,
+                     result,
+                     scratch1,
+                     scratch2,
+                     gc_required,
+                     TAG_OBJECT);
+
+  InitializeNewString(result,
+                      length,
+                      Heap::kSlicedStringMapRootIndex,
+                      scratch1,
+                      scratch2);
+}
+
+
+void MacroAssembler::AllocateAsciiSlicedString(Register result,
+                                               Register length,
+                                               Register scratch1,
+                                               Register scratch2,
+                                               Label* gc_required) {
+  AllocateInNewSpace(SlicedString::kSize,
+                     result,
+                     scratch1,
+                     scratch2,
+                     gc_required,
+                     TAG_OBJECT);
+
+  InitializeNewString(result,
+                      length,
+                      Heap::kSlicedAsciiStringMapRootIndex,
+                      scratch1,
+                      scratch2);
+}
+
+
 // Allocates a heap number or jumps to the label if the young space is full and
 // a scavenge is needed.
 void MacroAssembler::AllocateHeapNumber(Register result,

src/mips/macro-assembler-mips.h

@@ -362,6 +362,16 @@ class MacroAssembler: public Assembler {
                                Register scratch1,
                                Register scratch2,
                                Label* gc_required);
+  void AllocateTwoByteSlicedString(Register result,
+                                   Register length,
+                                   Register scratch1,
+                                   Register scratch2,
+                                   Label* gc_required);
+  void AllocateAsciiSlicedString(Register result,
+                                 Register length,
+                                 Register scratch1,
+                                 Register scratch2,
+                                 Label* gc_required);
 
   // Allocates a heap number or jumps to the gc_required label if the young
   // space is full and a scavenge is needed. All registers are clobbered also