[ThinLTO] optimize propagateAttributes performance

nocchijiang · nocchijiang · commit 87f2f663e4d7 · 2025-04-08T17:46:48.000+08:00
ModuleSummaryIndex::propagateAttributes() was observed to take about 25
minutes to complete on a ThinLTO application. Profiling revealed that
the majority of this time was spent operating on the
MarkedNonReadWriteOnly set.

By improving the hashing quality for ValueInfo, the execution time is
dramatically reduced to less than 10 seconds.
diff --git a/llvm/include/llvm/IR/ModuleSummaryIndex.h b/llvm/include/llvm/IR/ModuleSummaryIndex.h
@@ -300,7 +300,7 @@ template <> struct DenseMapInfo<ValueInfo> {
     assert(isSpecialKey(L) || isSpecialKey(R) || (L.haveGVs() == R.haveGVs()));
     return L.getRef() == R.getRef();
   }
-  static unsigned getHashValue(ValueInfo I) { return (uintptr_t)I.getRef(); }
+  static unsigned getHashValue(ValueInfo I) { return hash_value(I.getRef()); }
 };
 
 // For optional hinted size reporting, holds a pair of the full stack id

Original file line number	Diff line number	Diff line change
`@@ -300,7 +300,7 @@ template <> struct DenseMapInfo<ValueInfo> {`
`300`	`300`	`assert(isSpecialKey(L) \|\| isSpecialKey(R) \|\| (L.haveGVs() == R.haveGVs()));`
`301`	`301`	`return L.getRef() == R.getRef();`
`302`	`302`	`}`
`303`		`- static unsigned getHashValue(ValueInfo I) { return (uintptr_t)I.getRef(); }`
	`303`	`+ static unsigned getHashValue(ValueInfo I) { return hash_value(I.getRef()); }`
`304`	`304`	`};`
`305`	`305`
`306`	`306`	`// For optional hinted size reporting, holds a pair of the full stack id`