On 7/14/25 15:58, Segher Boessenkool wrote:
More interesting information is where the boundary is 🙂 There are a
lot of numbers under 400000, some bigger than others 😉
I'm sorry, I don't understand this comment about a "boundary"; on x86_64
I did not get a warning that PRE was disabled no matter how small I made
max-gcse-memory.
To elaborate:
1. On aarch64, PRE is disabled for some large routines in my project,
which was reported by the -Wdisabled-optimization flag, so I noticed
this while make'ing my project. In response, we set the size of
max-gcse-memory to 400000KB, so now PRE is disabled only for very large
routines.
2. I did not get any warnings from -Wdisabled-optimization on x86_64
Linux about PRE being disabled either with the default max-gcse-size
(128MB) or with the increased max-gcse-size (400000KB)
3. I concluded (maybe incorrectly) that PRE ran without problems on x86_64.
4. I wanted to see whether this was true, so I set max-gcse-memory to
400 (400KB), so small as to be almost certain to cause PRE to be disabled.
5. I did not get a notice that PRE was disabled from
-Wdisabled-optimization.
So, I don't understand what's going on. Is PRE run at all on this code
on x86_64?
Brad
