[PATCH] D99160: [X86][FastISEL] Support DW_TAG_call_site_parameter with FastISEL

Fri Apr 2 03:18:54 PDT 2021

djtodoro added a comment.

In D99160#2666066 <https://reviews.llvm.org/D99160#2666066>, @alok wrote:

> In D99160#2665580 <https://reviews.llvm.org/D99160#2665580>, @probinson wrote:
>
>> FastISel is normally used only at -O0, I wouldn't expect any parameters to be optimized out at -O0.
>> The test is running llc with default optimization, which is -O2, and forcing fast-isel; this is not a usual combination and I wouldn't expect us to spend any effort making sure debug info works well with that combination.
>>
>> If flang is forcing fast-isel even with optimization, that sounds like a problem for flang to solve, not LLVM.
>
> Thanks for your comments. I am sorry as the earlier used options in test case were more confusing than helpful. I have changed that now.
> The updated testcase at "-O0" with FastISel does have optimized out parameter, this is because generation of "DW_OP_GNU_entry_value" is enabled starting from "-O0". This causes llvm to generate it whenever it gets opportunity (more local variables to preserve may be the reason). 
> The concern here is only DW_OP_GNU_entry_value is not sufficient and should be supported with "DW_TAG_GNU_call_site_parameter", which I tried in current patch.

> "DW_OP_GNU_entry_value" is enabled starting from "-O0".

I am wondering if this is true...

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D99160/new/

https://reviews.llvm.org/D99160