[DemandedBits] Use SetVector for Worklist

DemandedBits currently uses a simple vector for the worklist, which
means that instructions may be inserted multiple times into it.
Especially in combination with the deep lattice, this may cause
instructions too be recomputed very often. To avoid this, switch
to a SetVector.

Differential Revision: https://reviews.llvm.org/D56362

llvm-svn: 350547

1 files changed, 6 insertions, 7 deletions

diff --git a/llvm/lib/Analysis/DemandedBits.cpp b/llvm/lib/Analysis/DemandedBits.cpp
index ba310d8d321..016399ff592 100644
--- a/llvm/lib/Analysis/DemandedBits.cpp
+++ b/llvm/lib/Analysis/DemandedBits.cpp
@@ -21,8 +21,7 @@
 
 #include "llvm/Analysis/DemandedBits.h"
 #include "llvm/ADT/APInt.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Analysis/AssumptionCache.h"
 #include "llvm/Analysis/ValueTracking.h"
@@ -315,7 +314,7 @@ void DemandedBits::performAnalysis() {
   AliveBits.clear();
   DeadUses.clear();
 
-  SmallVector<Instruction*, 128> Worklist;
+  SmallSetVector<Instruction*, 128> Worklist;
 
   // Collect the set of "root" instructions that are known live.
   for (Instruction &I : instructions(F)) {
@@ -330,7 +329,7 @@ void DemandedBits::performAnalysis() {
     Type *T = I.getType();
     if (T->isIntOrIntVectorTy()) {
       if (AliveBits.try_emplace(&I, T->getScalarSizeInBits(), 0).second)
-        Worklist.push_back(&I);
+        Worklist.insert(&I);
 
       continue;
     }
@@ -341,7 +340,7 @@ void DemandedBits::performAnalysis() {
         Type *T = J->getType();
         if (T->isIntOrIntVectorTy())
           AliveBits[J] = APInt::getAllOnesValue(T->getScalarSizeInBits());
-        Worklist.push_back(J);
+        Worklist.insert(J);
       }
     }
     // To save memory, we don't add I to the Visited set here. Instead, we
@@ -412,11 +411,11 @@ void DemandedBits::performAnalysis() {
           APInt ABNew = AB | ABPrev;
           if (ABNew != ABPrev || ABI == AliveBits.end()) {
             AliveBits[I] = std::move(ABNew);
-            Worklist.push_back(I);
+            Worklist.insert(I);
           }
         }
       } else if (I && !Visited.count(I)) {
-        Worklist.push_back(I);
+        Worklist.insert(I);
       }
     }
   }