[PatternMatch] Allow m_ConstantInt to match integer splats (llvm#153692)

When matching integers, `m_ConstantInt` is a convenient alternative to
`m_APInt` for matching unsigned 64-bit integers, allowing one to
simplify

```cpp
const APInt *IntC;
if (match(V, m_APInt(IntC))) {
  if (IntC->ule(UINT64_MAX)) {
    uint64_t Int = IntC->getZExtValue();
    // ...
  }
}
```
to
```cpp
uint64_t Int;
if (match(V, m_ConstantInt(Int))) {
  // ...
}
```

However, this simplification is only true if `V` is a scalar type.
Specifically, `m_APInt` also matches integer splats, but `m_ConstantInt`
does not.

This patch ensures that the matching behaviour of `m_ConstantInt`
parallels that of `m_APInt`, and also incorporates it in some obvious
places.

Author: zGoldthorpe

llvm/include/llvm/IR/PatternMatch.h

@@ -935,13 +935,14 @@ struct bind_const_intval_ty {
 
   bind_const_intval_ty(uint64_t &V) : VR(V) {}
 
-  template <typename ITy> bool match(ITy *V) {
-    if (const auto *CV = dyn_cast<ConstantInt>(V))
-      if (CV->getValue().ule(UINT64_MAX)) {
-        VR = CV->getZExtValue();
-        return true;
-      }
-    return false;
+  template <typename ITy> bool match(ITy *V) const {
+    const APInt *ConstInt;
+    if (!apint_match(ConstInt, /*AllowPoison=*/false).match(V))
+      return false;
+    if (ConstInt->getActiveBits() > 64)
+      return false;
+    VR = ConstInt->getZExtValue();
+    return true;
   }
 };
 

llvm/lib/Target/Hexagon/HexagonVectorCombine.cpp

@@ -1676,9 +1676,9 @@ auto HvxIdioms::matchFxpMul(Instruction &In) const -> std::optional<FxpOp> {
     return m_CombineOr(m_LShr(V, S), m_AShr(V, S));
   };
 
-  const APInt *Qn = nullptr;
-  if (Value * T; match(Exp, m_Shr(m_Value(T), m_APInt(Qn)))) {
-    Op.Frac = Qn->getZExtValue();
+  uint64_t Qn = 0;
+  if (Value *T; match(Exp, m_Shr(m_Value(T), m_ConstantInt(Qn)))) {
+    Op.Frac = Qn;
     Exp = T;
   } else {
     Op.Frac = 0;
@@ -1688,9 +1688,9 @@ auto HvxIdioms::matchFxpMul(Instruction &In) const -> std::optional<FxpOp> {
     return std::nullopt;
 
   // Check if there is rounding added.
-  const APInt *C = nullptr;
-  if (Value * T; Op.Frac > 0 && match(Exp, m_Add(m_Value(T), m_APInt(C)))) {
-    uint64_t CV = C->getZExtValue();
+  uint64_t CV;
+  if (Value *T;
+      Op.Frac > 0 && match(Exp, m_Add(m_Value(T), m_ConstantInt(CV)))) {
     if (CV != 0 && !isPowerOf2_64(CV))
       return std::nullopt;
     if (CV != 0)

llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp

@@ -1114,11 +1114,10 @@ static bool canEvaluateZExtd(Value *V, Type *Ty, unsigned &BitsToClear,
   case Instruction::Shl: {
     // We can promote shl(x, cst) if we can promote x.  Since shl overwrites the
     // upper bits we can reduce BitsToClear by the shift amount.
-    const APInt *Amt;
-    if (match(I->getOperand(1), m_APInt(Amt))) {
+    uint64_t ShiftAmt;
+    if (match(I->getOperand(1), m_ConstantInt(ShiftAmt))) {
       if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI))
         return false;
-      uint64_t ShiftAmt = Amt->getZExtValue();
       BitsToClear = ShiftAmt < BitsToClear ? BitsToClear - ShiftAmt : 0;
       return true;
     }
@@ -1127,11 +1126,11 @@ static bool canEvaluateZExtd(Value *V, Type *Ty, unsigned &BitsToClear,
   case Instruction::LShr: {
     // We can promote lshr(x, cst) if we can promote x.  This requires the
     // ultimate 'and' to clear out the high zero bits we're clearing out though.
-    const APInt *Amt;
-    if (match(I->getOperand(1), m_APInt(Amt))) {
+    uint64_t ShiftAmt;
+    if (match(I->getOperand(1), m_ConstantInt(ShiftAmt))) {
       if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI))
         return false;
-      BitsToClear += Amt->getZExtValue();
+      BitsToClear += ShiftAmt;
       if (BitsToClear > V->getType()->getScalarSizeInBits())
         BitsToClear = V->getType()->getScalarSizeInBits();
       return true;

llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

@@ -1499,11 +1499,11 @@ Instruction *InstCombinerImpl::foldICmpTruncConstant(ICmpInst &Cmp,
   // trunc iN (ShOp >> ShAmtC) to i[N - ShAmtC] < 0  --> ShOp <  0
   // trunc iN (ShOp >> ShAmtC) to i[N - ShAmtC] > -1 --> ShOp > -1
   Value *ShOp;
-  const APInt *ShAmtC;
+  uint64_t ShAmt;
   bool TrueIfSigned;
   if (isSignBitCheck(Pred, C, TrueIfSigned) &&
-      match(X, m_Shr(m_Value(ShOp), m_APInt(ShAmtC))) &&
-      DstBits == SrcBits - ShAmtC->getZExtValue()) {
+      match(X, m_Shr(m_Value(ShOp), m_ConstantInt(ShAmt))) &&
+      DstBits == SrcBits - ShAmt) {
     return TrueIfSigned ? new ICmpInst(ICmpInst::ICMP_SLT, ShOp,
                                        ConstantInt::getNullValue(SrcTy))
                         : new ICmpInst(ICmpInst::ICMP_SGT, ShOp,

llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp

@@ -317,10 +317,10 @@ static void annotateNonNullAndDereferenceable(CallInst *CI, ArrayRef<unsigned> A
     annotateDereferenceableBytes(CI, ArgNos, LenC->getZExtValue());
   } else if (isKnownNonZero(Size, DL)) {
     annotateNonNullNoUndefBasedOnAccess(CI, ArgNos);
-    const APInt *X, *Y;
+    uint64_t X, Y;
     uint64_t DerefMin = 1;
-    if (match(Size, m_Select(m_Value(), m_APInt(X), m_APInt(Y)))) {
-      DerefMin = std::min(X->getZExtValue(), Y->getZExtValue());
+    if (match(Size, m_Select(m_Value(), m_ConstantInt(X), m_ConstantInt(Y)))) {
+      DerefMin = std::min(X, Y);
       annotateDereferenceableBytes(CI, ArgNos, DerefMin);
     }
   }