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

src/s390/builtins-s390.cc

Index: src/s390/builtins-s390.cc
diff --git a/src/s390/builtins-s390.cc b/src/s390/builtins-s390.cc
index 2d521db65e3fb6ef4dce1e0633884c4ff8c71a5c..62c9da221df8f848ea1778f542e0cd09cd857c1d 100644
--- a/src/s390/builtins-s390.cc
+++ b/src/s390/builtins-s390.cc
@@ -2697,11 +2697,6 @@ void Builtins::Generate_AllocateInNewSpace(MacroAssembler* masm) {
   //  -- r3 : requested object size (untagged)
   //  -- lr : return address
   // -----------------------------------
-  Label runtime;
-  __ Allocate(r3, r2, r4, r5, &runtime, NO_ALLOCATION_FLAGS);
-  __ Ret();
-
-  __ bind(&runtime);
   __ SmiTag(r3);
   __ Push(r3);
   __ LoadSmiLiteral(cp, Smi::FromInt(0));
@@ -2714,11 +2709,6 @@ void Builtins::Generate_AllocateInOldSpace(MacroAssembler* masm) {
   //  -- r3 : requested object size (untagged)
   //  -- lr : return address
   // -----------------------------------
-  Label runtime;
-  __ Allocate(r3, r2, r4, r5, &runtime, PRETENURE);
-  __ Ret();
-
-  __ bind(&runtime);
   __ SmiTag(r3);
   __ LoadSmiLiteral(r4, Smi::FromInt(AllocateTargetSpace::encode(OLD_SPACE)));
   __ Push(r3, r4);