RE: [PATCH][ARC] Refurbish emitting DWARF2 for epilogue.

[Claudiu Zissulescu <Claudiu dot Zissulescu at synopsys dot com>]

H Joern,

> Or have some target hook to make it not even bother filling delay slots
> speculatively; for targets that can fully unexpose the delay slot, like SH and
> ARC >= ARC700, this aspect of fill_eager_delay_slots only mucks up
> schedules and increases code size.

I propose to solve the dwarf2 issues during epilogue by using the TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P hook for ARC processors. Hence, we do not need to emit the blockage instruction during epilogue. So, I have refactor the patch in two patches as follows:
	- The 0001-Refurbish-emitting-DWARF2-related-information-when-e.patch is the initial patch without emitting the blockage instruction during epilogue.
	- The 0002-ARC-Use-TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P-hook.patch adds TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P hook for ARC.

Both patches are attached.

> 
> More relevant ways to get data would be comparing the object files (from a
> whole toolchain library set and/or one or more big application(s)) built
> with/without the blockage insn emitted, or to benchmark it.

I did some testing here. For size, I used CSiBE testbench, and for speed, I used coremark and dhrystone. Using a blockage or not, doesn't affect the size or speed figures. However, using TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P hook betters the size figures (not much, just .1%), and improves the coremark by 2% and Dhrystone by 1%.

Hence, in the light of the new figures, I favor the above two patch solution. Both patches are checked using dg.exp and compile.exp. Ok to submit?

Thanks,
Claudiu

Attachment: 0001-Refurbish-emitting-DWARF2-related-information-when-e.patch
Description: 0001-Refurbish-emitting-DWARF2-related-information-when-e.patch

Attachment: 0002-ARC-Use-TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P-hook.patch
Description: 0002-ARC-Use-TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P-hook.patch