[llvm] [ctx_prof] Simple ICP criteria during module inliner (PR #109881)

[Kazu Hirata via llvm-commits]

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@@ -623,34 +623,37 @@ CallBase *llvm::promoteCallWithIfThenElse(CallBase &CB, Function &Callee,
     // All the ctx-es belonging to a function must have the same size counters.
     Ctx.resizeCounters(NewCountersSize);
 
-    // Maybe in this context, the indirect callsite wasn't observed at all
+    // Maybe in this context, the indirect callsite wasn't observed at all. That
+    // would make both direct and indirect BBs cold - which is what we already
+    // have from resising the counters.
     if (!Ctx.hasCallsite(CSIndex))
       return;
     auto &CSData = Ctx.callsite(CSIndex);
-    auto It = CSData.find(CalleeGUID);
 
-    // Maybe we did notice the indirect callsite, but to other targets.
-    if (It == CSData.end())
-      return;
-
-    assert(CalleeGUID == It->second.guid());
-
-    uint32_t DirectCount = It->second.getEntrycount();
-    uint32_t TotalCount = 0;
+    uint64_t TotalCount = 0;
     for (const auto &[_, V] : CSData)
       TotalCount += V.getEntrycount();
+    uint64_t DirectCount = 0;
+    // If we called the direct target, update the DirectCount. If we didn't, we
+    // still want to update the indirect BB (to which the TotalCount goes, in
+    // that case).
+    if (auto It = CSData.find(CalleeGUID); It != CSData.end()) {
+      assert(CalleeGUID == It->second.guid());
+      DirectCount = It->second.getEntrycount();
+      // This direct target needs to be moved to this caller under the
+      // newly-allocated callsite index.
+      assert(Ctx.callsites().count(NewCSID) == 0);
+      Ctx.ingestContext(NewCSID, std::move(It->second));
+      CSData.erase(CalleeGUID);
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kazutakahirata wrote:

Ah, I see.  Thank you for the explanation!

https://github.com/llvm/llvm-project/pull/109881