RFR (S): 8233702: Introduce helper function to clamp value to range

[Thomas Schatzl]

Hi all,

   I would like to introduce a small helper function to clamp a given 
value between a min/max value.
This would unclutter a few MIN(MAX(value, <min_value>), <max_value>) 
statements for imho better readability.

There are two places in (non-CMS) code remaining with the above 
statement, because in these cases it happens that a value min > max is 
passed, i.e. you potentially (already) get returned unexpected values.
(I did remove that assert in this webrev)

These are in

methodData.cpp:

int MethodData::compute_extra_data_count(int data_size, int 
empty_bc_count, bool needs_speculative_traps) {

933:     int extra_data_count = MIN2(empty_bc_count, MAX2(4, 
(empty_bc_count * 30) / 100));


hashtable.cpp:

template <MEMFLAGS F> BasicHashtableEntry<F>* 
BasicHashtable<F>::new_entry(unsigned int hashValue) {

64:       int block_size = MIN2(512, MAX2((int)_table_size / 2, 
(int)_number_of_entries));

I would like to ask the responsible teams (compiler and runtime) to give 
an opinion on these cases, i.e. if these should be converted (these are 
intentional) or I should file an RFE to investigate further.

CR:
https://bugs.openjdk.java.net/browse/JDK-8233702
Webrev:
http://cr.openjdk.java.net/~tschatzl/8233702/webrev/
Testing:
hs-tier1-5

Thanks,
   Thomas