[turbofan] Initial version of allocation folding and write barrier elimination.

src/ppc/builtins-ppc.cc

Index: src/ppc/builtins-ppc.cc
diff --git a/src/ppc/builtins-ppc.cc b/src/ppc/builtins-ppc.cc
index 3c8ace7d54f568e28d7445ae76e97fd0d2e26569..6dde86cf6dac3eca20dd712c534825d76de36150 100644
--- a/src/ppc/builtins-ppc.cc
+++ b/src/ppc/builtins-ppc.cc
@@ -2740,11 +2740,6 @@ void Builtins::Generate_AllocateInNewSpace(MacroAssembler* masm) {
   //  -- r4 : requested object size (untagged)
   //  -- lr : return address
   // -----------------------------------
-  Label runtime;
-  __ Allocate(r4, r3, r5, r6, &runtime, NO_ALLOCATION_FLAGS);
-  __ Ret();
-
-  __ bind(&runtime);
   __ SmiTag(r4);
   __ Push(r4);
   __ LoadSmiLiteral(cp, Smi::FromInt(0));
@@ -2757,11 +2752,6 @@ void Builtins::Generate_AllocateInOldSpace(MacroAssembler* masm) {
   //  -- r4 : requested object size (untagged)
   //  -- lr : return address
   // -----------------------------------
-  Label runtime;
-  __ Allocate(r4, r3, r5, r6, &runtime, PRETENURE);
-  __ Ret();
-
-  __ bind(&runtime);
   __ SmiTag(r4);
   __ LoadSmiLiteral(r5, Smi::FromInt(AllocateTargetSpace::encode(OLD_SPACE)));
   __ Push(r4, r5);