[CodeGenPrepare] Generalize inserted set from truncs to any inst.

It's been used before to avoid infinite loops caused by separate CGP
optimizations undoing one another.  We found one more such issue
caused by r238054.  To avoid it, generalize the "InsertedTruncs"
set to any inst, and use it to avoid touching those again.

llvm-svn: 239938

llvm/lib/CodeGen/CodeGenPrepare.cpp

@@ -135,8 +135,8 @@ class TypePromotionTransaction;
     /// multiple load/stores of the same address.
     ValueMap<Value*, Value*> SunkAddrs;
 
-    /// Keeps track of all truncates inserted for the current function.
-    SetOfInstrs InsertedTruncsSet;
+    /// Keeps track of all instructions inserted for the current function.
+    SetOfInstrs InsertedInsts;
     /// Keeps track of the type of the related instruction before their
     /// promotion for the current function.
     InstrToOrigTy PromotedInsts;
@@ -205,7 +205,7 @@ bool CodeGenPrepare::runOnFunction(Function &F) {
 
   bool EverMadeChange = false;
   // Clear per function information.
-  InsertedTruncsSet.clear();
+  InsertedInsts.clear();
   PromotedInsts.clear();
 
   ModifiedDT = false;
@@ -1406,6 +1406,9 @@ bool CodeGenPrepare::OptimizeCallInst(CallInst *CI, bool& ModifiedDT) {
         return false;
       // Sink a zext feeding stlxr/stxr before it, so it can be folded into it.
       ExtVal->moveBefore(CI);
+      // Mark this instruction as "inserted by CGP", so that other
+      // optimizations don't touch it.
+      InsertedInsts.insert(ExtVal);
       return true;
     }
     }
@@ -2107,8 +2110,8 @@ class AddressingModeMatcher {
   /// part of the return value of this addressing mode matching stuff.
   ExtAddrMode &AddrMode;
 
-  /// The truncate instruction inserted by other CodeGenPrepare optimizations.
-  const SetOfInstrs &InsertedTruncs;
+  /// The instructions inserted by other CodeGenPrepare optimizations.
+  const SetOfInstrs &InsertedInsts;
   /// A map from the instructions to their type before promotion.
   InstrToOrigTy &PromotedInsts;
   /// The ongoing transaction where every action should be registered.
@@ -2122,37 +2125,36 @@ class AddressingModeMatcher {
   AddressingModeMatcher(SmallVectorImpl<Instruction *> &AMI,
                         const TargetMachine &TM, Type *AT, unsigned AS,
                         Instruction *MI, ExtAddrMode &AM,
-                        const SetOfInstrs &InsertedTruncs,
+                        const SetOfInstrs &InsertedInsts,
                         InstrToOrigTy &PromotedInsts,
                         TypePromotionTransaction &TPT)
       : AddrModeInsts(AMI), TM(TM),
         TLI(*TM.getSubtargetImpl(*MI->getParent()->getParent())
                  ->getTargetLowering()),
         AccessTy(AT), AddrSpace(AS), MemoryInst(MI), AddrMode(AM),
-        InsertedTruncs(InsertedTruncs), PromotedInsts(PromotedInsts), TPT(TPT) {
+        InsertedInsts(InsertedInsts), PromotedInsts(PromotedInsts), TPT(TPT) {
     IgnoreProfitability = false;
   }
 public:
 
   /// Match - Find the maximal addressing mode that a load/store of V can fold,
   /// give an access type of AccessTy.  This returns a list of involved
   /// instructions in AddrModeInsts.
-  /// \p InsertedTruncs The truncate instruction inserted by other
-  /// CodeGenPrepare
+  /// \p InsertedInsts The instructions inserted by other CodeGenPrepare
   /// optimizations.
   /// \p PromotedInsts maps the instructions to their type before promotion.
   /// \p The ongoing transaction where every action should be registered.
   static ExtAddrMode Match(Value *V, Type *AccessTy, unsigned AS,
                            Instruction *MemoryInst,
                            SmallVectorImpl<Instruction*> &AddrModeInsts,
                            const TargetMachine &TM,
-                           const SetOfInstrs &InsertedTruncs,
+                           const SetOfInstrs &InsertedInsts,
                            InstrToOrigTy &PromotedInsts,
                            TypePromotionTransaction &TPT) {
     ExtAddrMode Result;
 
     bool Success = AddressingModeMatcher(AddrModeInsts, TM, AccessTy, AS,
-                                         MemoryInst, Result, InsertedTruncs,
+                                         MemoryInst, Result, InsertedInsts,
                                          PromotedInsts, TPT).MatchAddr(V, 0);
     (void)Success; assert(Success && "Couldn't select *anything*?");
     return Result;
@@ -2361,12 +2363,12 @@ class TypePromotionHelper {
   /// action to promote the operand of \p Ext instead of using Ext.
   /// \return NULL if no promotable action is possible with the current
   /// sign extension.
-  /// \p InsertedTruncs keeps track of all the truncate instructions inserted by
-  /// the others CodeGenPrepare optimizations. This information is important
+  /// \p InsertedInsts keeps track of all the instructions inserted by the
+  /// other CodeGenPrepare optimizations. This information is important
   /// because we do not want to promote these instructions as CodeGenPrepare
   /// will reinsert them later. Thus creating an infinite loop: create/remove.
   /// \p PromotedInsts maps the instructions to their type before promotion.
-  static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedTruncs,
+  static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedInsts,
                           const TargetLowering &TLI,
                           const InstrToOrigTy &PromotedInsts);
 };
@@ -2439,7 +2441,7 @@ bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
 }
 
 TypePromotionHelper::Action TypePromotionHelper::getAction(
-    Instruction *Ext, const SetOfInstrs &InsertedTruncs,
+    Instruction *Ext, const SetOfInstrs &InsertedInsts,
     const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {
   assert((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
          "Unexpected instruction type");
@@ -2455,7 +2457,7 @@ TypePromotionHelper::Action TypePromotionHelper::getAction(
   // Do not promote if the operand has been added by codegenprepare.
   // Otherwise, it means we are undoing an optimization that is likely to be
   // redone, thus causing potential infinite loop.
-  if (isa<TruncInst>(ExtOpnd) && InsertedTruncs.count(ExtOpnd))
+  if (isa<TruncInst>(ExtOpnd) && InsertedInsts.count(ExtOpnd))
     return nullptr;
 
   // SExt or Trunc instructions.
@@ -2839,7 +2841,7 @@ bool AddressingModeMatcher::MatchOperationAddr(User *AddrInst, unsigned Opcode,
     // Try to move this ext out of the way of the addressing mode.
     // Ask for a method for doing so.
     TypePromotionHelper::Action TPH =
-        TypePromotionHelper::getAction(Ext, InsertedTruncs, TLI, PromotedInsts);
+        TypePromotionHelper::getAction(Ext, InsertedInsts, TLI, PromotedInsts);
     if (!TPH)
       return false;
 
@@ -3157,7 +3159,7 @@ IsProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
     TypePromotionTransaction::ConstRestorationPt LastKnownGood =
         TPT.getRestorationPoint();
     AddressingModeMatcher Matcher(MatchedAddrModeInsts, TM, AddressAccessTy, AS,
-                                  MemoryInst, Result, InsertedTruncs,
+                                  MemoryInst, Result, InsertedInsts,
                                   PromotedInsts, TPT);
     Matcher.IgnoreProfitability = true;
     bool Success = Matcher.MatchAddr(Address, 0);
@@ -3240,7 +3242,7 @@ bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
     SmallVector<Instruction*, 16> NewAddrModeInsts;
     ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(
       V, AccessTy, AddrSpace, MemoryInst, NewAddrModeInsts, *TM,
-      InsertedTruncsSet, PromotedInsts, TPT);
+      InsertedInsts, PromotedInsts, TPT);
 
     // This check is broken into two cases with very similar code to avoid using
     // getNumUses() as much as possible. Some values have a lot of uses, so
@@ -3652,7 +3654,7 @@ bool CodeGenPrepare::ExtLdPromotion(TypePromotionTransaction &TPT,
       continue;
     // Get the action to perform the promotion.
     TypePromotionHelper::Action TPH = TypePromotionHelper::getAction(
-        I, InsertedTruncsSet, *TLI, PromotedInsts);
+        I, InsertedInsts, *TLI, PromotedInsts);
     // Check if we can promote.
     if (!TPH)
       continue;
@@ -3828,7 +3830,7 @@ bool CodeGenPrepare::OptimizeExtUses(Instruction *I) {
     if (!InsertedTrunc) {
       BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
       InsertedTrunc = new TruncInst(I, Src->getType(), "", InsertPt);
-      InsertedTruncsSet.insert(InsertedTrunc);
+      InsertedInsts.insert(InsertedTrunc);
     }
 
     // Replace a use of the {s|z}ext source with a use of the result.
@@ -4357,6 +4359,11 @@ bool CodeGenPrepare::OptimizeExtractElementInst(Instruction *Inst) {
 }
 
 bool CodeGenPrepare::OptimizeInst(Instruction *I, bool& ModifiedDT) {
+  // Bail out if we inserted the instruction to prevent optimizations from
+  // stepping on each other's toes.
+  if (InsertedInsts.count(I))
+    return false;
+
   if (PHINode *P = dyn_cast<PHINode>(I)) {
     // It is possible for very late stage optimizations (such as SimplifyCFG)
     // to introduce PHI nodes too late to be cleaned up.  If we detect such a

llvm/test/CodeGen/AArch64/arm64-atomic.ll

@@ -14,6 +14,22 @@ define i32 @val_compare_and_swap(i32* %p, i32 %cmp, i32 %new) #0 {
   ret i32 %val
 }
 
+define i32 @val_compare_and_swap_from_load(i32* %p, i32 %cmp, i32* %pnew) #0 {
+; CHECK-LABEL: val_compare_and_swap_from_load:
+; CHECK-NEXT: ldr    [[NEW:w[0-9]+]], [x2]
+; CHECK-NEXT: [[LABEL:.?LBB[0-9]+_[0-9]+]]:
+; CHECK-NEXT: ldaxr  [[RESULT:w[0-9]+]], [x0]
+; CHECK-NEXT: cmp    [[RESULT]], w1
+; CHECK-NEXT: b.ne   [[LABEL2:.?LBB[0-9]+_[0-9]+]]
+; CHECK-NEXT: stxr   [[SCRATCH_REG:w[0-9]+]], [[NEW]], [x0]
+; CHECK-NEXT: cbnz   [[SCRATCH_REG]], [[LABEL]]
+; CHECK-NEXT: [[LABEL2]]:
+  %new = load i32, i32* %pnew
+  %pair = cmpxchg i32* %p, i32 %cmp, i32 %new acquire acquire
+  %val = extractvalue { i32, i1 } %pair, 0
+  ret i32 %val
+}
+
 define i32 @val_compare_and_swap_rel(i32* %p, i32 %cmp, i32 %new) #0 {
 ; CHECK-LABEL: val_compare_and_swap_rel:
 ; CHECK-NEXT: [[LABEL:.?LBB[0-9]+_[0-9]+]]: