From: Daniel Berlin <dberlin@dberlin.org>
Date: Mon, 6 Mar 2017 18:42:39 +0000 (+0000)
Subject: NewGVN: Remove DebugUnknownExprs, just mark the instructions as unused
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c7849f87280d549f3829a2c2fe4cd911c421a0db;p=llvm

NewGVN: Remove DebugUnknownExprs, just mark the instructions as unused

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297047 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/NewGVN.cpp b/lib/Transforms/Scalar/NewGVN.cpp
index 5738cd69951..7750eabd72b 100644
--- a/lib/Transforms/Scalar/NewGVN.cpp
+++ b/lib/Transforms/Scalar/NewGVN.cpp
@@ -289,8 +289,6 @@ class NewGVN : public FunctionPass {
   // Deletion info.
   SmallPtrSet<Instruction *, 8> InstructionsToErase;
 
-  // The set of things we gave unknown expressions to due to debug counting.
-  SmallPtrSet<Instruction *, 8> DebugUnknownExprs;
 public:
   static char ID; // Pass identification, replacement for typeid.
   NewGVN() : FunctionPass(ID) {
@@ -1718,7 +1716,6 @@ void NewGVN::cleanupTables() {
   DominatedInstRange.clear();
   MemoryAccessToClass.clear();
   PredicateToUsers.clear();
-  DebugUnknownExprs.clear();
 }
 
 std::pair<unsigned, unsigned> NewGVN::assignDFSNumbers(BasicBlock *B,
@@ -1815,9 +1812,8 @@ void NewGVN::valueNumberInstruction(Instruction *I) {
     if (DebugCounter::shouldExecute(VNCounter)) {
       Symbolized = performSymbolicEvaluation(I);
     } else {
-      // Used to track which we marked unknown so we can skip verification of
-      // comparisons.
-      DebugUnknownExprs.insert(I);
+      // Mark the instruction as unused so we don't value number it again.
+      InstrDFS[I] = 0;
     }
     // If we couldn't come up with a symbolic expression, use the unknown
     // expression
@@ -1934,7 +1930,7 @@ void NewGVN::verifyComparisons(Function &F) {
     if (!ReachableBlocks.count(&BB))
       continue;
     for (auto &I : BB) {
-      if (InstructionsToErase.count(&I) || DebugUnknownExprs.count(&I))
+      if (InstrDFS.lookup(&I) == 0)
         continue;
       if (isa<CmpInst>(&I)) {
         auto *CurrentVal = ValueToClass.lookup(&I);