[InstSimplify] add folds for or-of-casted-icmps

[spatel]

Summary

The sibling folds for 'and' with casts were added with https://reviews.llvm.org/rL273200.
This is a preliminary step for adding the 'or' variants for the folds added with https://reviews.llvm.org/rL301260.

The reason for the strange form with constant LHS in the 1st test is because there's another missing fold in that case for the inverted predicate. That should be fixed when we add the ConstantRange functionality for 'or-of-icmps' that already exists for 'and-of-icmps'.

I'm not sure yet why the vector constant expression is not simplified in the 2nd test.

I'm hoping to share more code for the and/or cases, so we won't have these differences. This will allow us to remove code from InstCombine. It's also possible that we can remove some code here in InstSimplify. I think we have some duplicated folds because patterns are not matched in a general way.

[efriedma]

LGTM.

The second testcase isn't getting folded because ConstantFoldCastOperand isn't getting called (you call ConstantExpr::getCast and never attempt to fold it). IIRC there was a thread recently about a similar problem with InstSimplify of GEPs.

lib/Analysis/InstructionSimplify.cpp

if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) ||
       (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGE))
     return getTrue(Op0->getType());
 
   return nullptr;
 }
 
 /// Commuted variants are assumed to be handled by calling this function again
 /// with the parameters swapped.
-static Value *SimplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
+static Value *simplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
   if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true))
     return X;
 
   if (Value *X = simplifyAndOfICmpsWithSameOperands(Op0, Op1))
     return X;
 
   // FIXME: This should be shared with or-of-icmps.
   // Look for this pattern: (icmp V, C0) & (icmp V, C1)).
if (Delta == 1)
         return getFalse(ITy);
   }
 
   return nullptr;
 }
 
 /// Commuted variants are assumed to be handled by calling this function again
 /// with the parameters swapped.
-static Value *SimplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
+static Value *simplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
   if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false))
     return X;
 
   if (Value *X = simplifyOrOfICmpsWithSameOperands(Op0, Op1))
     return X;
 
   // (icmp (add V, C0), C1) | (icmp V, C0)
   ICmpInst::Predicate Pred0, Pred1;
if (C0->getBoolValue() && isNUW) {
     if (Delta == 1)
       if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE)
         return getTrue(ITy);
   }
 
   return nullptr;
 }
 
+static Value *simplifyPossiblyCastedAndOrOfICmps(ICmpInst *Cmp0, ICmpInst *Cmp1,
+                                                 bool IsAnd, CastInst *Cast) {
+  Value *V =
+      IsAnd ? simplifyAndOfICmps(Cmp0, Cmp1) : simplifyOrOfICmps(Cmp0, Cmp1);
+  if (!V)
+    return nullptr;
+  if (!Cast)
+    return V;
+
+  // If we looked through casts, we can only handle a constant simplification
+  // because we are not allowed to create a cast instruction here.
+  if (auto *C = dyn_cast<Constant>(V))
+    return ConstantExpr::getCast(Cast->getOpcode(), C, Cast->getType());
+
+  return nullptr;
+}
+
+static Value *simplifyAndOrOfICmps(Value *Op0, Value *Op1, bool IsAnd) {
+  // Look through casts of the 'and' operands to find compares.
+  auto *Cast0 = dyn_cast<CastInst>(Op0);
+  auto *Cast1 = dyn_cast<CastInst>(Op1);
+  if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() &&
+      Cast0->getSrcTy() == Cast1->getSrcTy()) {
+    Op0 = Cast0->getOperand(0);
+    Op1 = Cast1->getOperand(0);
+  }
+
+  auto *Cmp0 = dyn_cast<ICmpInst>(Op0);
+  auto *Cmp1 = dyn_cast<ICmpInst>(Op1);
+  if (!Cmp0 || !Cmp1)
+    return nullptr;
+
+  if (Value *V = simplifyPossiblyCastedAndOrOfICmps(Cmp0, Cmp1, IsAnd, Cast0))
+    return V;
+  if (Value *V = simplifyPossiblyCastedAndOrOfICmps(Cmp1, Cmp0, IsAnd, Cast0))
+    return V;
+
+  return nullptr;
+}
+
 /// Given operands for an And, see if we can fold the result.
 /// If not, this returns null.
 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
                               unsigned MaxRecurse) {
   if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q))
     return C;
 
   // X & undef -> 0
if (match(Op0, m_Neg(m_Specific(Op1))) ||
     if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
                                Q.DT))
       return Op0;
     if (isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
                                Q.DT))
       return Op1;
   }
 
-  if (auto *ICILHS = dyn_cast<ICmpInst>(Op0)) {
-    if (auto *ICIRHS = dyn_cast<ICmpInst>(Op1)) {
-      if (Value *V = SimplifyAndOfICmps(ICILHS, ICIRHS))
-        return V;
-      if (Value *V = SimplifyAndOfICmps(ICIRHS, ICILHS))
-        return V;
-    }
-  }
-
-  // The compares may be hidden behind casts. Look through those and try the
-  // same folds as above.
-  auto *Cast0 = dyn_cast<CastInst>(Op0);
-  auto *Cast1 = dyn_cast<CastInst>(Op1);
-  if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() &&
-      Cast0->getSrcTy() == Cast1->getSrcTy()) {
-    auto *Cmp0 = dyn_cast<ICmpInst>(Cast0->getOperand(0));
-    auto *Cmp1 = dyn_cast<ICmpInst>(Cast1->getOperand(0));
-    if (Cmp0 && Cmp1) {
-      Instruction::CastOps CastOpc = Cast0->getOpcode();
-      Type *ResultType = Cast0->getType();
-      if (auto *V = dyn_cast_or_null<Constant>(SimplifyAndOfICmps(Cmp0, Cmp1)))
-        return ConstantExpr::getCast(CastOpc, V, ResultType);
-      if (auto *V = dyn_cast_or_null<Constant>(SimplifyAndOfICmps(Cmp1, Cmp0)))
-        return ConstantExpr::getCast(CastOpc, V, ResultType);
-    }
-  }
+  if (Value *V = simplifyAndOrOfICmps(Op0, Op1, true))
 
   // Try some generic simplifications for associative operations.
   if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
                                           MaxRecurse))
     return V;
 
   // And distributes over Or.  Try some generic simplifications based on this.
   if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
static Value *SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
   // (A ^ B) | (~B & A) -> (A ^ B)
   // (B ^ A) | (A & ~B) -> (B ^ A)
   // (B ^ A) | (~B & A) -> (B ^ A)
   if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
       (match(Op1, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) ||
        match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))))
     return Op0;
 
-  if (auto *ICILHS = dyn_cast<ICmpInst>(Op0)) {
-    if (auto *ICIRHS = dyn_cast<ICmpInst>(Op1)) {
-      if (Value *V = SimplifyOrOfICmps(ICILHS, ICIRHS))
-        return V;
-      if (Value *V = SimplifyOrOfICmps(ICIRHS, ICILHS))
-        return V;
-    }
-  }
+  if (Value *V = simplifyAndOrOfICmps(Op0, Op1, false))
 
   // Try some generic simplifications for associative operations.
   if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
                                           MaxRecurse))
     return V;
 
   // Or distributes over And.  Try some generic simplifications based on this.
   if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,

test/Transforms/InstSimplify/AndOrXor.ll

;
   %cmp0 = icmp eq <2 x i8> %i, zeroinitializer
   %conv0 = zext <2 x i1> %cmp0 to <2 x i3>
   %cmp1 = icmp ugt <2 x i16> %j, <i16 1, i16 1>
   %conv1 = zext <2 x i1> %cmp1 to <2 x i3>
   %and = and <2 x i3> %conv0, %conv1
   ret <2 x i3> %and
 }
 
-; FIXME: This should simplify.
-
 define i32 @or_of_zexted_icmps(i32 %i) {
 ; CHECK-LABEL: @or_of_zexted_icmps(
-; CHECK-NEXT:    [[CMP0:%.*]] = icmp ne i32 %i, 0
-; CHECK-NEXT:    [[CONV0:%.*]] = zext i1 [[CMP0]] to i32
-; CHECK-NEXT:    [[CMP1:%.*]] = icmp uge i32 4, %i
-; CHECK-NEXT:    [[CONV1:%.*]] = zext i1 [[CMP1]] to i32
-; CHECK-NEXT:    [[OR:%.*]] = or i32 [[CONV0]], [[CONV1]]
-; CHECK-NEXT:    ret i32 [[OR]]
+; CHECK-NEXT:    ret i32 1
 ;
   %cmp0 = icmp ne i32 %i, 0
   %conv0 = zext i1 %cmp0 to i32
   %cmp1 = icmp uge i32 4, %i
   %conv1 = zext i1 %cmp1 to i32
   %or = or i32 %conv0, %conv1
   ret i32 %or
 }
 
-; FIXME: This should simplify 
 ; Try a different cast and weird vector types.
 
 define i3 @or_of_bitcast_icmps_vec(<3 x i65> %i) {
 ; CHECK-LABEL: @or_of_bitcast_icmps_vec(
-; CHECK-NEXT:    [[CMP0:%.*]] = icmp sge <3 x i65> %i, zeroinitializer
-; CHECK-NEXT:    [[CONV0:%.*]] = bitcast <3 x i1> [[CMP0]] to i3
-; CHECK-NEXT:    [[CMP1:%.*]] = icmp slt <3 x i65> %i, zeroinitializer
-; CHECK-NEXT:    [[CONV1:%.*]] = bitcast <3 x i1> [[CMP1]] to i3
-; CHECK-NEXT:    [[OR:%.*]] = or i3 [[CONV0]], [[CONV1]]
-; CHECK-NEXT:    ret i3 [[OR]]
+; CHECK-NEXT:    ret i3 bitcast (<3 x i1> <i1 true, i1 true, i1 true> to i3)
 ;
   %cmp0 = icmp sge <3 x i65> %i, zeroinitializer
   %conv0 = bitcast <3 x i1> %cmp0 to i3
   %cmp1 = icmp slt <3 x i65> %i, zeroinitializer
   %conv1 = bitcast <3 x i1> %cmp1 to i3
   %or = or i3 %conv0, %conv1
   ret i3 %or
 }