1 files changed, 108 insertions, 57 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 04877bec94ec..ca87477c5d81 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -333,7 +333,7 @@ Instruction *InstCombinerImpl::commonCastTransforms(CastInst &CI) {
         SrcTy->getNumElements() == DestTy->getNumElements() &&
         SrcTy->getPrimitiveSizeInBits() == DestTy->getPrimitiveSizeInBits()) {
       Value *CastX = Builder.CreateCast(CI.getOpcode(), X, DestTy);
-      return new ShuffleVectorInst(CastX, UndefValue::get(DestTy), Mask);
+      return new ShuffleVectorInst(CastX, Mask);
     }
   }
 
@@ -701,10 +701,10 @@ static Instruction *shrinkSplatShuffle(TruncInst &Trunc,
   if (Shuf && Shuf->hasOneUse() && match(Shuf->getOperand(1), m_Undef()) &&
       is_splat(Shuf->getShuffleMask()) &&
       Shuf->getType() == Shuf->getOperand(0)->getType()) {
-    // trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Undef, SplatMask
-    Constant *NarrowUndef = UndefValue::get(Trunc.getType());
+    // trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Poison, SplatMask
+    // trunc (shuf X, Poison, SplatMask) --> shuf (trunc X), Poison, SplatMask
     Value *NarrowOp = Builder.CreateTrunc(Shuf->getOperand(0), Trunc.getType());
-    return new ShuffleVectorInst(NarrowOp, NarrowUndef, Shuf->getShuffleMask());
+    return new ShuffleVectorInst(NarrowOp, Shuf->getShuffleMask());
   }
 
   return nullptr;
@@ -961,14 +961,25 @@ Instruction *InstCombinerImpl::visitTrunc(TruncInst &Trunc) {
       return BinaryOperator::CreateAdd(NarrowCtlz, WidthDiff);
     }
   }
+
+  if (match(Src, m_VScale(DL))) {
+    if (Trunc.getFunction() &&
+        Trunc.getFunction()->hasFnAttribute(Attribute::VScaleRange)) {
+      unsigned MaxVScale = Trunc.getFunction()
+                               ->getFnAttribute(Attribute::VScaleRange)
+                               .getVScaleRangeArgs()
+                               .second;
+      if (MaxVScale > 0 && Log2_32(MaxVScale) < DestWidth) {
+        Value *VScale = Builder.CreateVScale(ConstantInt::get(DestTy, 1));
+        return replaceInstUsesWith(Trunc, VScale);
+      }
+    }
+  }
+
   return nullptr;
 }
 
-/// Transform (zext icmp) to bitwise / integer operations in order to
-/// eliminate it. If DoTransform is false, just test whether the given
-/// (zext icmp) can be transformed.
-Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp, ZExtInst &Zext,
-                                                 bool DoTransform) {
+Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp, ZExtInst &Zext) {
   // If we are just checking for a icmp eq of a single bit and zext'ing it
   // to an integer, then shift the bit to the appropriate place and then
   // cast to integer to avoid the comparison.
@@ -977,10 +988,8 @@ Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp, ZExtInst &Zext,
 
     // zext (x <s  0) to i32 --> x>>u31      true if signbit set.
     // zext (x >s -1) to i32 --> (x>>u31)^1  true if signbit clear.
-    if ((Cmp->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isNullValue()) ||
-        (Cmp->getPredicate() == ICmpInst::ICMP_SGT && Op1CV->isAllOnesValue())) {
-      if (!DoTransform) return Cmp;
-
+    if ((Cmp->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isZero()) ||
+        (Cmp->getPredicate() == ICmpInst::ICMP_SGT && Op1CV->isAllOnes())) {
       Value *In = Cmp->getOperand(0);
       Value *Sh = ConstantInt::get(In->getType(),
                                    In->getType()->getScalarSizeInBits() - 1);
@@ -1004,7 +1013,7 @@ Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp, ZExtInst &Zext,
     // zext (X != 0) to i32 --> X>>1     iff X has only the 2nd bit set.
     // zext (X != 1) to i32 --> X^1      iff X has only the low bit set.
     // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
-    if ((Op1CV->isNullValue() || Op1CV->isPowerOf2()) &&
+    if ((Op1CV->isZero() || Op1CV->isPowerOf2()) &&
         // This only works for EQ and NE
         Cmp->isEquality()) {
       // If Op1C some other power of two, convert:
@@ -1012,10 +1021,8 @@ Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp, ZExtInst &Zext,
 
       APInt KnownZeroMask(~Known.Zero);
       if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
-        if (!DoTransform) return Cmp;
-
         bool isNE = Cmp->getPredicate() == ICmpInst::ICMP_NE;
-        if (!Op1CV->isNullValue() && (*Op1CV != KnownZeroMask)) {
+        if (!Op1CV->isZero() && (*Op1CV != KnownZeroMask)) {
           // (X&4) == 2 --> false
           // (X&4) != 2 --> true
           Constant *Res = ConstantInt::get(Zext.getType(), isNE);
@@ -1031,7 +1038,7 @@ Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp, ZExtInst &Zext,
                                   In->getName() + ".lobit");
         }
 
-        if (!Op1CV->isNullValue() == isNE) { // Toggle the low bit.
+        if (!Op1CV->isZero() == isNE) { // Toggle the low bit.
           Constant *One = ConstantInt::get(In->getType(), 1);
           In = Builder.CreateXor(In, One);
         }
@@ -1053,9 +1060,6 @@ Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp, ZExtInst &Zext,
     if (Cmp->hasOneUse() && match(Cmp->getOperand(1), m_ZeroInt()) &&
         match(Cmp->getOperand(0),
               m_OneUse(m_c_And(m_Shl(m_One(), m_Value(ShAmt)), m_Value(X))))) {
-      if (!DoTransform)
-        return Cmp;
-
       if (Cmp->getPredicate() == ICmpInst::ICMP_EQ)
         X = Builder.CreateNot(X);
       Value *Lshr = Builder.CreateLShr(X, ShAmt);
@@ -1077,8 +1081,6 @@ Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp, ZExtInst &Zext,
         APInt KnownBits = KnownLHS.Zero | KnownLHS.One;
         APInt UnknownBit = ~KnownBits;
         if (UnknownBit.countPopulation() == 1) {
-          if (!DoTransform) return Cmp;
-
           Value *Result = Builder.CreateXor(LHS, RHS);
 
           // Mask off any bits that are set and won't be shifted away.
@@ -1316,51 +1318,37 @@ Instruction *InstCombinerImpl::visitZExt(ZExtInst &CI) {
   if (ICmpInst *Cmp = dyn_cast<ICmpInst>(Src))
     return transformZExtICmp(Cmp, CI);
 
-  BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
-  if (SrcI && SrcI->getOpcode() == Instruction::Or) {
-    // zext (or icmp, icmp) -> or (zext icmp), (zext icmp) if at least one
-    // of the (zext icmp) can be eliminated. If so, immediately perform the
-    // according elimination.
-    ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
-    ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
-    if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
-        LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType() &&
-        (transformZExtICmp(LHS, CI, false) ||
-         transformZExtICmp(RHS, CI, false))) {
-      // zext (or icmp, icmp) -> or (zext icmp), (zext icmp)
-      Value *LCast = Builder.CreateZExt(LHS, CI.getType(), LHS->getName());
-      Value *RCast = Builder.CreateZExt(RHS, CI.getType(), RHS->getName());
-      Value *Or = Builder.CreateOr(LCast, RCast, CI.getName());
-      if (auto *OrInst = dyn_cast<Instruction>(Or))
-        Builder.SetInsertPoint(OrInst);
-
-      // Perform the elimination.
-      if (auto *LZExt = dyn_cast<ZExtInst>(LCast))
-        transformZExtICmp(LHS, *LZExt);
-      if (auto *RZExt = dyn_cast<ZExtInst>(RCast))
-        transformZExtICmp(RHS, *RZExt);
-
-      return replaceInstUsesWith(CI, Or);
-    }
-  }
-
   // zext(trunc(X) & C) -> (X & zext(C)).
   Constant *C;
   Value *X;
-  if (SrcI &&
-      match(SrcI, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Constant(C)))) &&
+  if (match(Src, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Constant(C)))) &&
       X->getType() == CI.getType())
     return BinaryOperator::CreateAnd(X, ConstantExpr::getZExt(C, CI.getType()));
 
   // zext((trunc(X) & C) ^ C) -> ((X & zext(C)) ^ zext(C)).
   Value *And;
-  if (SrcI && match(SrcI, m_OneUse(m_Xor(m_Value(And), m_Constant(C)))) &&
+  if (match(Src, m_OneUse(m_Xor(m_Value(And), m_Constant(C)))) &&
       match(And, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Specific(C)))) &&
       X->getType() == CI.getType()) {
     Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
     return BinaryOperator::CreateXor(Builder.CreateAnd(X, ZC), ZC);
   }
 
+  if (match(Src, m_VScale(DL))) {
+    if (CI.getFunction() &&
+        CI.getFunction()->hasFnAttribute(Attribute::VScaleRange)) {
+      unsigned MaxVScale = CI.getFunction()
+                               ->getFnAttribute(Attribute::VScaleRange)
+                               .getVScaleRangeArgs()
+                               .second;
+      unsigned TypeWidth = Src->getType()->getScalarSizeInBits();
+      if (MaxVScale > 0 && Log2_32(MaxVScale) < TypeWidth) {
+        Value *VScale = Builder.CreateVScale(ConstantInt::get(DestTy, 1));
+        return replaceInstUsesWith(CI, VScale);
+      }
+    }
+  }
+
   return nullptr;
 }
 
@@ -1605,6 +1593,32 @@ Instruction *InstCombinerImpl::visitSExt(SExtInst &CI) {
     return BinaryOperator::CreateAShr(A, NewShAmt);
   }
 
+  // Splatting a bit of constant-index across a value:
+  // sext (ashr (trunc iN X to iM), M-1) to iN --> ashr (shl X, N-M), N-1
+  // TODO: If the dest type is different, use a cast (adjust use check).
+  if (match(Src, m_OneUse(m_AShr(m_Trunc(m_Value(X)),
+                                 m_SpecificInt(SrcBitSize - 1)))) &&
+      X->getType() == DestTy) {
+    Constant *ShlAmtC = ConstantInt::get(DestTy, DestBitSize - SrcBitSize);
+    Constant *AshrAmtC = ConstantInt::get(DestTy, DestBitSize - 1);
+    Value *Shl = Builder.CreateShl(X, ShlAmtC);
+    return BinaryOperator::CreateAShr(Shl, AshrAmtC);
+  }
+
+  if (match(Src, m_VScale(DL))) {
+    if (CI.getFunction() &&
+        CI.getFunction()->hasFnAttribute(Attribute::VScaleRange)) {
+      unsigned MaxVScale = CI.getFunction()
+                               ->getFnAttribute(Attribute::VScaleRange)
+                               .getVScaleRangeArgs()
+                               .second;
+      if (MaxVScale > 0 && Log2_32(MaxVScale) < (SrcBitSize - 1)) {
+        Value *VScale = Builder.CreateVScale(ConstantInt::get(DestTy, 1));
+        return replaceInstUsesWith(CI, VScale);
+      }
+    }
+  }
+
   return nullptr;
 }
 
@@ -2060,6 +2074,19 @@ Instruction *InstCombinerImpl::visitPtrToInt(PtrToIntInst &CI) {
     return CastInst::CreateIntegerCast(P, Ty, /*isSigned=*/false);
   }
 
+  if (auto *GEP = dyn_cast<GetElementPtrInst>(SrcOp)) {
+    // Fold ptrtoint(gep null, x) to multiply + constant if the GEP has one use.
+    // While this can increase the number of instructions it doesn't actually
+    // increase the overall complexity since the arithmetic is just part of
+    // the GEP otherwise.
+    if (GEP->hasOneUse() &&
+        isa<ConstantPointerNull>(GEP->getPointerOperand())) {
+      return replaceInstUsesWith(CI,
+                                 Builder.CreateIntCast(EmitGEPOffset(GEP), Ty,
+                                                       /*isSigned=*/false));
+    }
+  }
+
   Value *Vec, *Scalar, *Index;
   if (match(SrcOp, m_OneUse(m_InsertElt(m_IntToPtr(m_Value(Vec)),
                                         m_Value(Scalar), m_Value(Index)))) &&
@@ -2133,9 +2160,9 @@ optimizeVectorResizeWithIntegerBitCasts(Value *InVal, VectorType *DestTy,
   if (SrcElts > DestElts) {
     // If we're shrinking the number of elements (rewriting an integer
     // truncate), just shuffle in the elements corresponding to the least
-    // significant bits from the input and use undef as the second shuffle
+    // significant bits from the input and use poison as the second shuffle
     // input.
-    V2 = UndefValue::get(SrcTy);
+    V2 = PoisonValue::get(SrcTy);
     // Make sure the shuffle mask selects the "least significant bits" by
     // keeping elements from back of the src vector for big endian, and from the
     // front for little endian.
@@ -2528,7 +2555,7 @@ Instruction *InstCombinerImpl::optimizeBitCastFromPhi(CastInst &CI,
         // As long as the user is another old PHI node, then even if we don't
         // rewrite it, the PHI web we're considering won't have any users
         // outside itself, so it'll be dead.
-        if (OldPhiNodes.count(PHI) == 0)
+        if (!OldPhiNodes.contains(PHI))
           return nullptr;
       } else {
         return nullptr;
@@ -2736,6 +2763,30 @@ Instruction *InstCombinerImpl::visitBitCast(BitCastInst &CI) {
       if (auto *InsElt = dyn_cast<InsertElementInst>(Src))
         return new BitCastInst(InsElt->getOperand(1), DestTy);
     }
+
+    // Convert an artificial vector insert into more analyzable bitwise logic.
+    unsigned BitWidth = DestTy->getScalarSizeInBits();
+    Value *X, *Y;
+    uint64_t IndexC;
+    if (match(Src, m_OneUse(m_InsertElt(m_OneUse(m_BitCast(m_Value(X))),
+                                        m_Value(Y), m_ConstantInt(IndexC)))) &&
+        DestTy->isIntegerTy() && X->getType() == DestTy &&
+        isDesirableIntType(BitWidth)) {
+      // Adjust for big endian - the LSBs are at the high index.
+      if (DL.isBigEndian())
+        IndexC = SrcVTy->getNumElements() - 1 - IndexC;
+
+      // We only handle (endian-normalized) insert to index 0. Any other insert
+      // would require a left-shift, so that is an extra instruction.
+      if (IndexC == 0) {
+        // bitcast (inselt (bitcast X), Y, 0) --> or (and X, MaskC), (zext Y)
+        unsigned EltWidth = Y->getType()->getScalarSizeInBits();
+        APInt MaskC = APInt::getHighBitsSet(BitWidth, BitWidth - EltWidth);
+        Value *AndX = Builder.CreateAnd(X, MaskC);
+        Value *ZextY = Builder.CreateZExt(Y, DestTy);
+        return BinaryOperator::CreateOr(AndX, ZextY);
+      }
+    }
   }
 
   if (auto *Shuf = dyn_cast<ShuffleVectorInst>(Src)) {