[CSSPGO] Relax size limitation for priority inlining with preinlined profile

[hoy]

Summary

As a follow-up to D124632, I'm turning on unlimited size caps for inlining with preinlined profile. It should be safe as a preinlined profile has "bounded" inline contexts.

No noticeable size or perf delta was seen with two of our internal large services, but I think this is still a good change to be consistent with the other case.

[wenlei]

lgtm, thanks.

llvm/lib/Transforms/IPO/SampleProfile.cpp

if (!CallsitePrioritizedInline.getNumOccurrences())
       CallsitePrioritizedInline = true;
     // For CSSPGO, we also allow recursive inline to best use context profile.
     if (!AllowRecursiveInline.getNumOccurrences())
       AllowRecursiveInline = true;
 
     if (Reader->profileIsPreInlined()) {
       if (!UsePreInlinerDecision.getNumOccurrences())
         UsePreInlinerDecision = true;
-    } else if (!Reader->profileIsCS()) {
+    }
+
+    if (!Reader->profileIsCS()) {
       // Non-CS profile should be fine without a function size budget for the
-      // inliner since the contexts in the profile are all from inlining in
-      // the prevoius build, thus they are bounded.
+      // inliner since the contexts in the profile are either all from inlining
+      // in the prevoius build or pre-computed by the preinliner with a size
+      // cap, thus they are bounded.
       if (!ProfileInlineLimitMin.getNumOccurrences())
         ProfileInlineLimitMin = std::numeric_limits<unsigned>::max();
       if (!ProfileInlineLimitMax.getNumOccurrences())
         ProfileInlineLimitMax = std::numeric_limits<unsigned>::max();
     }
   }
 
   if (Reader->profileIsCS()) {