compiler,runtime: Determine if allocations need new pointers in runtime.

As the removed comment states, if the package being compiled played
    certain tricks with pointers that looked like integers, the compiler
    might allocate space for new pointers unnecessarily.  Since the type
    information on the heap is now precise, this logic can be moved to the
    runtime.
    
    Reviewed-on: https://go-review.googlesource.com/11581

From-SVN: r225757

gcc/go/gofrontend/MERGE

@@ -1,4 +1,4 @@
-83191e8e2cb9f47f7c1e6bcb9997f21163292612
+2c985e4781691fea3eb4171de85265bfbc4e4997
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

gcc/go/gofrontend/gogo.cc

@@ -4391,15 +4391,7 @@ Gogo::allocate_memory(Type* type, Location location)
   Expression* td = Expression::make_type_descriptor(type, location);
   Expression* size =
     Expression::make_type_info(type, Expression::TYPE_INFO_SIZE);
-
-  // If this package imports unsafe, then it may play games with
-  // pointers that look like integers.  We should be able to determine
-  // whether or not to use new pointers in libgo/go-new.c.  FIXME.
-  bool use_new_pointers = this->imported_unsafe_ || type->has_pointer();
-  return Runtime::make_call((use_new_pointers
-			     ? Runtime::NEW
-			     : Runtime::NEW_NOPOINTERS),
-			    location, 2, td, size);
+  return Runtime::make_call(Runtime::NEW, location, 2, td, size);
 }
 
 // Traversal class used to check for return statements.

gcc/go/gofrontend/runtime.def

@@ -223,10 +223,6 @@ DEF_GO_RUNTIME(REGISTER_GC_ROOTS, "__go_register_gc_roots", P1(POINTER), R0())
 // Allocate memory.
 DEF_GO_RUNTIME(NEW, "__go_new", P2(TYPE, UINTPTR), R1(POINTER))
 
-// Allocate memory which can not contain pointers.
-DEF_GO_RUNTIME(NEW_NOPOINTERS, "__go_new_nopointers", P2(TYPE, UINTPTR), R1(POINTER))
-
-
 // Start a new goroutine.
 DEF_GO_RUNTIME(GO, "__go_go", P2(FUNC_PTR, POINTER), R0())
 

libgo/runtime/go-new.c

@@ -8,19 +8,12 @@
 #include "runtime.h"
 #include "arch.h"
 #include "malloc.h"
+#include "go-type.h"
 
 void *
 __go_new (const struct __go_type_descriptor *td, uintptr_t size)
 {
   return runtime_mallocgc (size,
 			   (uintptr) td | TypeInfo_SingleObject,
-			   0);
-}
-
-void *
-__go_new_nopointers (const struct __go_type_descriptor *td,  uintptr_t size)
-{
-  return runtime_mallocgc (size,
-			   (uintptr) td | TypeInfo_SingleObject,
-			   FlagNoScan);
+			   td->__code & GO_NO_POINTERS ? FlagNoScan : 0);
 }