On 8/3/23 17:38, Vineet Gupta wrote:
;-) Actually if you wanted to poke at zicond, the most interesting
unexplored area I've come across is the COND_EXPR handling in gimple.
When we expand a COND_EXPR into RTL the first approach we take is to
try mov<mode>cc in RTL.
Unfortunately we don't create COND_EXPRs all that often in gimple.
Some simple match.pd patterns would likely really help here.
The problem is RTL expansion when mov<mode>cc FAILs is usually poor at
best. So if we're going to add those match.pd patterns, we probably
need to beef up the RTL expansion code to do a better job when the
target doesn't have a mov<mode>cc RTL pattern.
Ok, I'll add that to my todo list.
You might want to reach out to Andrew Pinski if you do poke at this. I
made a reference to this issue in a BZ he recently commented on. It was
an x86 issue with cmov generation, but the same core issue applies --
we're not generating COND_EXPRs very aggressively in gimple.
jeff
