[llvm] [ValueTracking] Filter out non-interesting conditions (PR #118493)

[Nikita Popov via llvm-commits]

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@@ -18,18 +18,34 @@
 #define LLVM_ANALYSIS_DOMCONDITIONCACHE_H
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/BitmaskEnum.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"
+#include <cstdint>
 
 namespace llvm {
 
 class Value;
 class BranchInst;
 
+enum class DomConditionFlag : uint8_t {
+  None = 0,
+  KnownBits = 1 << 0,
+  KnownFPClass = 1 << 1,
+  PowerOfTwo = 1 << 2,
+  ICmp = 1 << 3,
+};
+
+LLVM_DECLARE_ENUM_AS_BITMASK(
+    DomConditionFlag,
+    /*LargestValue=*/static_cast<uint8_t>(DomConditionFlag::ICmp));
+
 class DomConditionCache {
 private:
   /// A map of values about which a branch might be providing information.
-  using AffectedValuesMap = DenseMap<Value *, SmallVector<BranchInst *, 1>>;
+  using AffectedValuesMap =
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nikic wrote:

>From some quick profiling, the impact isn't from registerBranch, but from extra DT queries in computeKnownBits. I think in principle this patch should still help as long as we don't add comparisons where both sides are variables to the KnownBits category (https://github.com/llvm/llvm-project/commit/338d7fc5b72e20f1606a28f740d5a0068c95d94b#r152360307).

https://github.com/llvm/llvm-project/pull/118493