Test case "ext/standard/tests/array/range.phpt" failed on ARM64 machine
only under RELEASE mode.
How to reproduce it:
```
./buildconf -f; ./configure; make -j 128
make test TESTS="-d opcache.enable=1 -d opcache.enable_cli=1 ext/standard/tests/array/range.phpt"
```
Root cause:
I suspect the root cause is that on ARM64 machine, PHP RELEASE mode
produces different values for internal function range() compared to
DEBUG mode.
Take the downsized test case downsize-range.php [1] as an example. We
applied the check-element.diff patch to check the original values. Note
that we print out the floating point numbers with precision 16.
From the outputs in file output.md, we can see the 7-th and 9-th
elements are different between RELEASE and DEBUG.
To be honest, I didn't get where such difference comes from and probably
this is due to different compilation options used by RELEASED and DEBUG.
Fix:
After commit [2], serialize_precision is used for var_dump(). As a
result, the pre-set "precision=14" didn't work actually.
In this patch, we turn to set serialize_precision as 14 and therefore
the difference between RELEASE and DEBUG can be eliminated.
Note-1: this failue didn't occur on x86 machine.
Note-2: in my local test, this is the only test case which behaves
differently on ARM64 machine under RELEASE and DEBUG mode.
[1] https://gist.github.com/shqking/0d55abf8dbaafde4a00ea9304e71f06b
[2] https://github.com/php/php-src/commit/a939805
Change-Id: I9293e990925590f8d7cfb2462d8d760abf76069f
var_dump() is debugging functionality, so it should print
floating-point numbers accurately. We do this by switching
to serialize_precision, which (by default) will print with
as much precision as necessary to preserve the exact value
of the float.
This also affects debug_zval_dump().
Closes GH-5172.
