RFR (S) 8165929: Constify arguments of Copy methods

[Kim Barrett]

> On Feb 7, 2018, at 10:35 AM, coleen.phillimore at oracle.com wrote:
> 
> I actually didn't see any calls where const was cast away, and I wasn't going to change them anyway.  Most of the calls to the Copy functions cast both arguments to HeapWord when there's casting involved.  Anyway, this should help for future uses and cleanups. This is very limited and hopefully a very boring review.
> 
> I wasn't able to test PPC and AARCH64,

or S390 (see second item below)

> but tested Oracle's current and former supported platforms with this change (note 32 bit arm reverses arguments to one of the _Copy functions).   I compiled with Zero but can't run Zero for some reason unrelated.
> 
> open webrev at http://cr.openjdk.java.net/~coleenp/8165929.01/webrev
> bug link https://bugs.openjdk.java.net/browse/JDK-8165929
> 
> Thanks,
> Coleen

Looks good.  A small number of minor issues, for which I don't need a
new webrev.

------------------------------------------------------------------------------ 
src/hotspot/cpu/s390/copy_s390.hpp
 108 static bool has_destructive_overlap(const char* from, char* to, size_t byte_count) {

Pre-existing:

I think this function should take [const] void* arguments and locally
convert for arithmetic, rather than forcing nearly all callers to cast
arguments.  But that's not a problem with this changeset.

------------------------------------------------------------------------------ 
src/hotspot/cpu/s390/copy_s390.hpp
1030 static void pd_arrayof_conjoint_oops(HeapWord* from, HeapWord* to, size_t count) {

Missed a const qualifier here.

------------------------------------------------------------------------------
src/hotspot/cpu/sparc/copy_sparc.hpp
 118   pd_conjoint_oops_atomic((oop*)from, (oop*)to, count);
 143   pd_conjoint_jshorts_atomic((jshort*)from, (jshort*)to, count);
 147   pd_conjoint_jints_atomic((jint*)from, (jint*)to, count);
 151   pd_conjoint_jlongs_atomic((jlong*)from, (jlong*)to, count);
 155   pd_conjoint_oops_atomic((oop*)from, (oop*)to, count);

For consistency, these casts of from ought to retain const. 

------------------------------------------------------------------------------ 
src/hotspot/os_cpu/linux_x86/copy_linux_x86.inline.hpp
 288   pd_conjoint_jints_atomic((jint*)from, (jint*)to, count);
 296   pd_conjoint_jlongs_atomic((jlong*)from, (jlong*)to, count);
 305   pd_conjoint_oops_atomic((oop*)from, (oop*)to, count);

For consistency, these casts of from ought to retain const. 

------------------------------------------------------------------------------ 
src/hotspot/os_cpu/windows_x86/copy_windows_x86.inline.hpp
 122   pd_conjoint_oops_atomic((oop*)from, (oop*)to, count);

For consistency, these casts of from ought to retain const. 

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