From: Sergey Kachkov <sergey.kachkov@syntacore.com>
Date: Mon, 16 Jan 2023 12:13:17 +0000 (+0300)
Subject: Revert "[GVN] Refactor handling of pointer-select in GVN pass"
X-Git-Tag: upstream/17.0.6~20817
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=868abc471d1060175f71d2749badd864b1ba4f92;p=platform%2Fupstream%2Fllvm.git

Revert "[GVN] Refactor handling of pointer-select in GVN pass"

This reverts commit fc7cdaa373308ce3d72218b4d80101ae19850a6c.
---

diff --git a/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h b/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h
index b99807a..24b4673 100644
--- a/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h
+++ b/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h
@@ -79,10 +79,6 @@ class MemDepResult {
     ///      the calls are the same.
     Def,
 
-    /// This marker indicates that the query has dependency from select
-    /// instruction.
-    Select,
-
     /// This marker indicates that the query has no known dependency in the
     /// specified block.
     ///
@@ -110,7 +106,6 @@ class MemDepResult {
       DepType, PointerSumTypeMember<Invalid, Instruction *>,
       PointerSumTypeMember<Clobber, Instruction *>,
       PointerSumTypeMember<Def, Instruction *>,
-      PointerSumTypeMember<Select, Instruction *>,
       PointerSumTypeMember<Other, PointerEmbeddedInt<OtherType, 3>>>;
   ValueTy Value;
 
@@ -129,9 +124,6 @@ public:
     assert(Inst && "Clobber requires inst");
     return MemDepResult(ValueTy::create<Clobber>(Inst));
   }
-  static MemDepResult getSelect(Instruction *Inst) {
-    return MemDepResult(ValueTy::create<Select>(Inst));
-  }
   static MemDepResult getNonLocal() {
     return MemDepResult(ValueTy::create<Other>(NonLocal));
   }
@@ -150,13 +142,6 @@ public:
   /// definition dependency.
   bool isDef() const { return Value.is<Def>(); }
 
-  /// Tests if this MemDepResult represents a query that is an instruction
-  /// select dependency.
-  bool isSelect() const { return Value.is<Select>(); }
-
-  /// Tests if this MemDepResult represents a local query (Clobber/Def/Select).
-  bool isLocal() const { return isClobber() || isDef() || isSelect(); }
-
   /// Tests if this MemDepResult represents a query that is transparent to the
   /// start of the block, but where a non-local hasn't been done.
   bool isNonLocal() const {
@@ -185,8 +170,6 @@ public:
       return Value.cast<Clobber>();
     case Def:
       return Value.cast<Def>();
-    case Select:
-      return Value.cast<Select>();
     case Other:
       return nullptr;
     }
diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
index 960679b..7a13e7a 100644
--- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -592,11 +592,6 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
         return MemDepResult::getDef(Inst);
     }
 
-    // If we found a select instruction for MemLoc pointer, return it as
-    // Select dependency.
-    if (isa<SelectInst>(Inst) && MemLoc.Ptr == Inst)
-      return MemDepResult::getSelect(Inst);
-
     if (isInvariantLoad)
       continue;
 
@@ -967,7 +962,7 @@ MemDepResult MemoryDependenceResults::getNonLocalInfoForBlock(
   // If the block has a dependency (i.e. it isn't completely transparent to
   // the value), remember the reverse association because we just added it
   // to Cache!
-  if (!Dep.isLocal())
+  if (!Dep.isDef() && !Dep.isClobber())
     return Dep;
 
   // Keep the ReverseNonLocalPtrDeps map up to date so we can efficiently
diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index e542efb..f9fdd77 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -1120,26 +1120,31 @@ static void reportMayClobberedLoad(LoadInst *Load, MemDepResult DepInfo,
 /// 1. The pointer select (\p Address) must be defined in \p DepBB.
 /// 2. Both value operands of the pointer select must be loaded in the same
 /// basic block, before the pointer select.
-/// 3. There must be no instructions between the found loads and \p Sel that may
+/// 3. There must be no instructions between the found loads and \p End that may
 /// clobber the loads.
 static std::optional<AvailableValue>
-tryToConvertLoadOfPtrSelect(SelectInst *Sel, Type *LoadTy, DominatorTree &DT,
+tryToConvertLoadOfPtrSelect(BasicBlock *DepBB, BasicBlock::iterator End,
+                            Value *Address, Type *LoadTy, DominatorTree &DT,
                             AAResults *AA) {
+
+  auto *Sel = dyn_cast_or_null<SelectInst>(Address);
+  if (!Sel || DepBB != Sel->getParent())
+    return std::nullopt;
+
   LoadInst *L1 = findDominatingLoad(Sel->getOperand(1), LoadTy, Sel, DT);
   LoadInst *L2 = findDominatingLoad(Sel->getOperand(2), LoadTy, Sel, DT);
   if (!L1 || !L2)
     return std::nullopt;
 
   // Ensure there are no accesses that may modify the locations referenced by
-  // either L1 or L2 between L1, L2 and the specified Sel instruction.
+  // either L1 or L2 between L1, L2 and the specified End iterator.
   Instruction *EarlierLoad = L1->comesBefore(L2) ? L1 : L2;
   MemoryLocation L1Loc = MemoryLocation::get(L1);
   MemoryLocation L2Loc = MemoryLocation::get(L2);
-  if (any_of(make_range(EarlierLoad->getIterator(), Sel->getIterator()),
-             [&](Instruction &I) {
-               return isModSet(AA->getModRefInfo(&I, L1Loc)) ||
-                      isModSet(AA->getModRefInfo(&I, L2Loc));
-             }))
+  if (any_of(make_range(EarlierLoad->getIterator(), End), [&](Instruction &I) {
+        return isModSet(AA->getModRefInfo(&I, L1Loc)) ||
+               isModSet(AA->getModRefInfo(&I, L2Loc));
+      }))
     return std::nullopt;
 
   return AvailableValue::getSelect(Sel);
@@ -1148,21 +1153,20 @@ tryToConvertLoadOfPtrSelect(SelectInst *Sel, Type *LoadTy, DominatorTree &DT,
 std::optional<AvailableValue>
 GVNPass::AnalyzeLoadAvailability(LoadInst *Load, MemDepResult DepInfo,
                                  Value *Address) {
-  assert(Load->isUnordered() && "rules below are incorrect for ordered access");
-  assert(DepInfo.isLocal() && "expected a local dependence");
-
-  Instruction *DepInst = DepInfo.getInst();
-  if (DepInfo.isSelect()) {
-    // Check if load with Addr dependent from select can be converted to select
-    // between load values. There must be no instructions between the found
-    // loads and DepInst that may clobber the loads.
-    assert(isa<SelectInst>(DepInst) && "Dependency must be select instruction");
-    auto *Sel = cast<SelectInst>(DepInst);
-    return tryToConvertLoadOfPtrSelect(Sel, Load->getType(), getDominatorTree(),
-                                       getAliasAnalysis());
+  if (!DepInfo.isDef() && !DepInfo.isClobber()) {
+    assert(isa<SelectInst>(Address));
+    return tryToConvertLoadOfPtrSelect(Load->getParent(), Load->getIterator(),
+                                       Address, Load->getType(),
+                                       getDominatorTree(), getAliasAnalysis());
   }
 
+  assert((DepInfo.isDef() || DepInfo.isClobber()) &&
+         "expected a local dependence");
+  assert(Load->isUnordered() && "rules below are incorrect for ordered access");
+
   const DataLayout &DL = Load->getModule()->getDataLayout();
+
+  Instruction *DepInst = DepInfo.getInst();
   if (DepInfo.isClobber()) {
     // If the dependence is to a store that writes to a superset of the bits
     // read by the load, we can extract the bits we need for the load from the
@@ -1294,15 +1298,24 @@ void GVNPass::AnalyzeLoadAvailability(LoadInst *Load, LoadDepVect &Deps,
       continue;
     }
 
-    if (!DepInfo.isLocal()) {
+    // The address being loaded in this non-local block may not be the same as
+    // the pointer operand of the load if PHI translation occurs.  Make sure
+    // to consider the right address.
+    Value *Address = Dep.getAddress();
+
+    if (!DepInfo.isDef() && !DepInfo.isClobber()) {
+      if (auto R = tryToConvertLoadOfPtrSelect(
+              DepBB, DepBB->end(), Address, Load->getType(), getDominatorTree(),
+              getAliasAnalysis())) {
+        ValuesPerBlock.push_back(
+            AvailableValueInBlock::get(DepBB, std::move(*R)));
+        continue;
+      }
       UnavailableBlocks.push_back(DepBB);
       continue;
     }
 
-    // The address being loaded in this non-local block may not be the same as
-    // the pointer operand of the load if PHI translation occurs.  Make sure
-    // to consider the right address.
-    if (auto AV = AnalyzeLoadAvailability(Load, DepInfo, Dep.getAddress())) {
+    if (auto AV = AnalyzeLoadAvailability(Load, DepInfo, Address)) {
       // subtlety: because we know this was a non-local dependency, we know
       // it's safe to materialize anywhere between the instruction within
       // DepInfo and the end of it's block.
@@ -2030,8 +2043,9 @@ bool GVNPass::processLoad(LoadInst *L) {
   if (Dep.isNonLocal())
     return processNonLocalLoad(L);
 
+  Value *Address = L->getPointerOperand();
   // Only handle the local case below
-  if (!Dep.isLocal()) {
+  if (!Dep.isDef() && !Dep.isClobber() && !isa<SelectInst>(Address)) {
     // This might be a NonFuncLocal or an Unknown
     LLVM_DEBUG(
         // fast print dep, using operator<< on instruction is too slow.
@@ -2040,7 +2054,7 @@ bool GVNPass::processLoad(LoadInst *L) {
     return false;
   }
 
-  auto AV = AnalyzeLoadAvailability(L, Dep, L->getPointerOperand());
+  auto AV = AnalyzeLoadAvailability(L, Dep, Address);
   if (!AV)
     return false;
 
diff --git a/llvm/test/Transforms/GVN/PRE/pre-load-through-select.ll b/llvm/test/Transforms/GVN/PRE/pre-load-through-select.ll
index e53aa97..af1a13a 100644
--- a/llvm/test/Transforms/GVN/PRE/pre-load-through-select.ll
+++ b/llvm/test/Transforms/GVN/PRE/pre-load-through-select.ll
@@ -236,15 +236,13 @@ define i32 @test_pointer_phi_select_simp_store_clobber_3(ptr %a, ptr %b, ptr %c,
 ; CHECK-NEXT:    [[L_1:%.*]] = load i32, ptr [[A:%.*]], align 4
 ; CHECK-NEXT:    [[L_2:%.*]] = load i32, ptr [[B:%.*]], align 4
 ; CHECK-NEXT:    [[CMP_I_I_I:%.*]] = icmp ult i32 [[L_1]], [[L_2]]
-; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[CMP_I_I_I]], i32 [[L_1]], i32 [[L_2]]
 ; CHECK-NEXT:    [[MIN_SELECT:%.*]] = select i1 [[CMP_I_I_I]], ptr [[A]], ptr [[B]]
 ; CHECK-NEXT:    br label [[EXIT:%.*]]
 ; CHECK:       else:
-; CHECK-NEXT:    [[RES_2_PRE:%.*]] = load i32, ptr [[A]], align 4
 ; CHECK-NEXT:    br label [[EXIT]]
 ; CHECK:       exit:
-; CHECK-NEXT:    [[RES_2:%.*]] = phi i32 [ [[SELECT]], [[THEN]] ], [ [[RES_2_PRE]], [[ELSE]] ]
 ; CHECK-NEXT:    [[P:%.*]] = phi ptr [ [[MIN_SELECT]], [[THEN]] ], [ [[A]], [[ELSE]] ]
+; CHECK-NEXT:    [[RES_2:%.*]] = load i32, ptr [[P]], align 4
 ; CHECK-NEXT:    ret i32 [[RES_2]]
 ;
 entry: