[NFCI][PromoteMem2Reg] Don't handle the first successor out of order

llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp

@@ -424,8 +424,8 @@ struct PromoteMem2Reg {
                            const SmallPtrSetImpl<BasicBlock *> &DefBlocks,
                            SmallPtrSetImpl<BasicBlock *> &LiveInBlocks);
   void RenamePass(BasicBlock *BB, BasicBlock *Pred,
-                  RenamePassData::ValVector &IncVals,
-                  RenamePassData::LocationVector &IncLocs,
+                  RenamePassData::ValVector IncVals,
+                  RenamePassData::LocationVector IncLocs,
                   std::vector<RenamePassData> &Worklist);
   bool QueuePhiNode(BasicBlock *BB, unsigned AllocaIdx, unsigned &Version);
 
@@ -869,7 +869,8 @@ void PromoteMem2Reg::run() {
     RenamePassData RPD = std::move(RenamePassWorkList.back());
     RenamePassWorkList.pop_back();
     // RenamePass may add new worklist entries.
-    RenamePass(RPD.BB, RPD.Pred, RPD.Values, RPD.Locations, RenamePassWorkList);
+    RenamePass(RPD.BB, RPD.Pred, std::move(RPD.Values),
+               std::move(RPD.Locations), RenamePassWorkList);
   } while (!RenamePassWorkList.empty());
 
   // Remove the allocas themselves from the function.
@@ -1096,10 +1097,9 @@ static void updateForIncomingValueLocation(PHINode *PN, DebugLoc DL,
 /// IncomingVals indicates what value each Alloca contains on exit from the
 /// predecessor block Pred.
 void PromoteMem2Reg::RenamePass(BasicBlock *BB, BasicBlock *Pred,
-                                RenamePassData::ValVector &IncomingVals,
-                                RenamePassData::LocationVector &IncomingLocs,
+                                RenamePassData::ValVector IncomingVals,
+                                RenamePassData::LocationVector IncomingLocs,
                                 std::vector<RenamePassData> &Worklist) {
-NextIteration:
   // If we are inserting any phi nodes into this BB, they will already be in the
   // block.
   if (PHINode *APN = dyn_cast<PHINode>(BB->begin())) {
@@ -1215,24 +1215,22 @@ void PromoteMem2Reg::RenamePass(BasicBlock *BB, BasicBlock *Pred,
   }
 
   // 'Recurse' to our successors.
-  succ_iterator I = succ_begin(BB), E = succ_end(BB);
-  if (I == E)
-    return;
 
   // Keep track of the successors so we don't visit the same successor twice
   SmallPtrSet<BasicBlock *, 8> VisitedSuccs;
 
-  // Handle the first successor without using the worklist.
-  VisitedSuccs.insert(*I);
-  Pred = BB;
-  BB = *I;
-  ++I;
-
-  for (; I != E; ++I)
-    if (VisitedSuccs.insert(*I).second)
-      Worklist.emplace_back(*I, Pred, IncomingVals, IncomingLocs);
-
-  goto NextIteration;
+  for (BasicBlock *S : reverse(successors(BB)))
+    if (VisitedSuccs.insert(S).second) {
+      if (VisitedSuccs.size() == 1) {
+        // Let the first successor to own allocated arrays.
+        Worklist.emplace_back(S, BB, std::move(IncomingVals),
+                              std::move(IncomingLocs));
+      } else {
+        // Other successors have to make a copy.
+        Worklist.emplace_back(S, BB, Worklist.back().Values,
+                              Worklist.back().Locations);
+      }
+    }
 }
 
 void llvm::PromoteMemToReg(ArrayRef<AllocaInst *> Allocas, DominatorTree &DT,

llvm/test/Transforms/InstCombine/2009-02-20-InstCombine-SROA.ll

@@ -215,7 +215,7 @@ define ptr @_Z3fooRSt6vectorIiSaIiEE(ptr %X) {
 ; IC_SROA-NEXT:    [[TMP27:%.*]] = getelementptr i8, ptr [[__FIRST_ADDR_I_I_SROA_0_0]], i32 4
 ; IC_SROA-NEXT:    br label [[BB18_I_I]]
 ; IC_SROA:       bb18.i.i:
-; IC_SROA-NEXT:    [[__FIRST_ADDR_I_I_SROA_0_1:%.*]] = phi ptr [ [[TMP27]], [[BB17_I_I]] ], [ [[__FIRST_ADDR_I_I_SROA_0_0]], [[BB13_I_I]] ]
+; IC_SROA-NEXT:    [[__FIRST_ADDR_I_I_SROA_0_1:%.*]] = phi ptr [ [[__FIRST_ADDR_I_I_SROA_0_0]], [[BB13_I_I]] ], [ [[TMP27]], [[BB17_I_I]] ]
 ; IC_SROA-NEXT:    [[TMP28:%.*]] = load i32, ptr [[__FIRST_ADDR_I_I_SROA_0_1]], align 4
 ; IC_SROA-NEXT:    [[TMP29:%.*]] = icmp eq i32 [[TMP28]], 42
 ; IC_SROA-NEXT:    br i1 [[TMP29]], label [[BB20_I_I:%.*]], label [[BB21_I_I:%.*]]
@@ -225,7 +225,7 @@ define ptr @_Z3fooRSt6vectorIiSaIiEE(ptr %X) {
 ; IC_SROA-NEXT:    [[TMP30:%.*]] = getelementptr i8, ptr [[__FIRST_ADDR_I_I_SROA_0_1]], i32 4
 ; IC_SROA-NEXT:    br label [[BB22_I_I]]
 ; IC_SROA:       bb22.i.i:
-; IC_SROA-NEXT:    [[__FIRST_ADDR_I_I_SROA_0_2:%.*]] = phi ptr [ [[TMP30]], [[BB21_I_I]] ], [ [[__FIRST_ADDR_I_I_SROA_0_0]], [[BB13_I_I]] ]
+; IC_SROA-NEXT:    [[__FIRST_ADDR_I_I_SROA_0_2:%.*]] = phi ptr [ [[__FIRST_ADDR_I_I_SROA_0_0]], [[BB13_I_I]] ], [ [[TMP30]], [[BB21_I_I]] ]
 ; IC_SROA-NEXT:    [[TMP31:%.*]] = load i32, ptr [[__FIRST_ADDR_I_I_SROA_0_2]], align 4
 ; IC_SROA-NEXT:    [[TMP32:%.*]] = icmp eq i32 [[TMP31]], 42
 ; IC_SROA-NEXT:    br i1 [[TMP32]], label [[BB24_I_I:%.*]], label [[BB25_I_I:%.*]]

llvm/test/Transforms/SimplifyCFG/Hexagon/switch-to-lookup-table.ll

@@ -43,7 +43,7 @@ define i32 @foo(i32 %x) #0 section ".tcm_text" {
 ; DISABLE:       sw.default:
 ; DISABLE-NEXT:    br label [[RETURN]]
 ; DISABLE:       return:
-; DISABLE-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ 19, [[SW_DEFAULT]] ], [ 33, [[SW_BB5]] ], [ 12, [[SW_BB4]] ], [ 22, [[SW_BB3]] ], [ 14, [[SW_BB2]] ], [ 20, [[SW_BB1]] ], [ 9, [[ENTRY:%.*]] ]
+; DISABLE-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ 19, [[SW_DEFAULT]] ], [ 20, [[SW_BB1]] ], [ 14, [[SW_BB2]] ], [ 22, [[SW_BB3]] ], [ 12, [[SW_BB4]] ], [ 33, [[SW_BB5]] ], [ 9, [[ENTRY:%.*]] ]
 ; DISABLE-NEXT:    ret i32 [[RETVAL_0]]
 ;
 entry: