Add inlined isAssignableFrom test on X #22629
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matthewhall2 force-pushed the inlined_isAssignableFrom_X branch 6 times, most recently from 81c678a to ef01e3f Compare Adds inlined isAssignableFrom test, skipping the slow helper in most cases. Signed-off-by: Matthew Hall <matthew.hall3@outlook.com>
matthewhall2 force-pushed the inlined_isAssignableFrom_X branch from ef01e3f to eb0f0cd Compare 
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I think the changes look functionally correct. Just a couple of mainly cosmetic comments.
May I also ask you to change "isAssignableFrom" to "Class.isAssignableFrom" in the commit title and body, just for clarity?
One additional question: are there cases where the JIT can determine at compile-time whether the Class objects involved are array classes or interface classes? I'm just wondering how often the opportunity to eliminate any of the run-time tests arises in practice.
| */ | ||
| bool supportsInliningOfIsAssignableFrom() { return false; } // no virt, default | ||
| | ||
| /** \brief |
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| */ | ||
| bool supportsInliningOfIsAssignableFrom(); | ||
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| /** \brief |
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| } else { | ||
| break; | ||
| } |
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This is just a nit, but may I suggest removing the break from the else block and dropping the else?
| TR::Register *temp1Reg = cg->allocateRegister(); | ||
| TR::Register *temp2Reg = cg->allocateRegister(); |
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I believe that with this change, temp1Reg and temp2Reg are no longer used, so these two lines can be removed.
| debugObj->addInstructionComment(cursor, "-->load depth of toClass"); | ||
| } | ||
| | ||
| // cast class depth >= obj class depth, throw |
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As this might be generating code in a context where failure won't throw an exception, I think "throw" here should be changed to "fail"
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Adds inlined isAssignableFrom test, skipping the slow helper in most cases.
Commons out superclass test and itable walk from
generateInlinedCheckCastForDynamicCastClasssince isAssignableFrom uses the same tests