[SCCP] Move logic for removing ssa.copy into Solver (NFC)

So it can be reused between IPSCCP and SCCP.

Make the implementation a bit more efficient by only lookup the
PredicateInfo once.

Author: nikic

llvm/include/llvm/Transforms/Utils/SCCPSolver.h

@@ -77,6 +77,8 @@ class SCCPSolver {
   LLVM_ABI void addPredicateInfo(Function &F, DominatorTree &DT,
                                  AssumptionCache &AC);
 
+  LLVM_ABI void removeSSACopies(Function &F);
+
   /// markBlockExecutable - This method can be used by clients to mark all of
   /// the blocks that are known to be intrinsically live in the processed unit.
   /// This returns true if the block was not considered live before.

llvm/lib/Transforms/IPO/SCCP.cpp

@@ -250,19 +250,7 @@ static bool runIPSCCP(
       if (!DeadBB->hasAddressTaken())
         DTU.deleteBB(DeadBB);
 
-    for (BasicBlock &BB : F) {
-      for (Instruction &Inst : llvm::make_early_inc_range(BB)) {
-        if (Solver.getPredicateInfoFor(&Inst)) {
-          if (auto *II = dyn_cast<IntrinsicInst>(&Inst)) {
-            if (II->getIntrinsicID() == Intrinsic::ssa_copy) {
-              Value *Op = II->getOperand(0);
-              Inst.replaceAllUsesWith(Op);
-              Inst.eraseFromParent();
-            }
-          }
-        }
-      }
-    }
+    Solver.removeSSACopies(F);
   }
 
   // If we inferred constant or undef return values for a function, we replaced

llvm/lib/Transforms/Utils/SCCPSolver.cpp

@@ -764,6 +764,26 @@ class SCCPInstVisitor : public InstVisitor<SCCPInstVisitor> {
     FnPredicateInfo.insert({&F, std::make_unique<PredicateInfo>(F, DT, AC)});
   }
 
+  void removeSSACopies(Function &F) {
+    auto It = FnPredicateInfo.find(&F);
+    if (It == FnPredicateInfo.end())
+      return;
+
+    for (BasicBlock &BB : F) {
+      for (Instruction &Inst : llvm::make_early_inc_range(BB)) {
+        if (It->second->getPredicateInfoFor(&Inst)) {
+          if (auto *II = dyn_cast<IntrinsicInst>(&Inst)) {
+            if (II->getIntrinsicID() == Intrinsic::ssa_copy) {
+              Value *Op = II->getOperand(0);
+              Inst.replaceAllUsesWith(Op);
+              Inst.eraseFromParent();
+            }
+          }
+        }
+      }
+    }
+  }
+
   void visitCallInst(CallInst &I) { visitCallBase(I); }
 
   bool markBlockExecutable(BasicBlock *BB);
@@ -2168,6 +2188,10 @@ void SCCPSolver::addPredicateInfo(Function &F, DominatorTree &DT,
   Visitor->addPredicateInfo(F, DT, AC);
 }
 
+void SCCPSolver::removeSSACopies(Function &F) {
+  Visitor->removeSSACopies(F);
+}
+
 bool SCCPSolver::markBlockExecutable(BasicBlock *BB) {
   return Visitor->markBlockExecutable(BB);
 }