RFR(S) 8189439: Parameters type profiling is not performed from aarch64 interpreter
aph at redhat.com
Thu Nov 30 10:21:16 UTC 2017
On 30/11/17 09:47, Boris wrote:
> [this time in plain text]
> Please review bugfix to enable parameters type profiling missing in
> aarch64 interpreter to make it consistent with other ports.
> Additionally to aarch64 specific change I am going to add shared jtreg
> test to discover the case I have fixed. The test is very similar to
> TestArrayCopyNoInitDeopt.java (see JDK-8188221, Return type profiling is
> not performed from aarch64 interpreter). The test expects to see
> additional C2 deoptimization caused by speculative type check when
> profiling data became outdated.
> Existing profile_parameters_type() got minor fix and it is now used in
> interpreted method entries.
Good catch! Some comments:
In this hunk, there is one other change needed:
1753 // Load the offset of the area within the MDO used for
1754 // parameters. If it's negative we're not profiling any parameters
1755 ldr(tmp1, Address(mdp, in_bytes(MethodData::parameters_type_data_di_offset()) - in_bytes(MethodData::data_offset())));
I think this should be ldrw.
1756 tbnz(tmp1, 31, profile_continue); // i.e. sign bit set
The changes to orptr don't seem to do anything. There is no need to
parameterize rscratch1, which is available as a scratch register to
all assembler macros. Is there a register conflict in there
somewhere? I'm wondering if perhaps we should get rid of optr
altogether, because it does not help readability at all.
In this hunk, tmp1 and tmp2 doesn't seem to have any purpose. All they
do is make the code more complicated.
1674 Register tmp1 = r1;
1675 Register tmp2 = r2;
1676 Register mdp = r4;
1677 Label no_mdp;
1678 __ ldr(mdp, Address(rmethod, Method::method_data_offset()));
1679 __ cbz(mdp, no_mdp);
1680 __ add(mdp, mdp, in_bytes(MethodData::data_offset()));
1681 __ profile_parameters_type(mdp, tmp1, tmp2);
1682 __ bind(no_mdp);
Java Platform Lead Engineer
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