[Constant] Add containsPoisonElement

This patch

- Adds containsPoisonElement that checks existence of poison in constant vector elements,
- Renames containsUndefElement to containsUndefOrPoisonElement to clarify its behavior & updates its uses properly

With this patch, isGuaranteedNotToBeUndefOrPoison's tests w.r.t constant vectors are added because its analysis is improved.

Thanks!

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D94053

1 files changed, 18 insertions, 7 deletions

diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index a38302d..5aa819d 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -304,31 +304,42 @@ bool Constant::isElementWiseEqual(Value *Y) const {
   return isa<UndefValue>(CmpEq) || match(CmpEq, m_One());
 }
 
-bool Constant::containsUndefElement() const {
-  if (auto *VTy = dyn_cast<VectorType>(getType())) {
-    if (isa<UndefValue>(this))
+static bool
+containsUndefinedElement(const Constant *C,
+                         function_ref<bool(const Constant *)> HasFn) {
+  if (auto *VTy = dyn_cast<VectorType>(C->getType())) {
+    if (HasFn(C))
       return true;
-    if (isa<ConstantAggregateZero>(this))
+    if (isa<ConstantAggregateZero>(C))
       return false;
-    if (isa<ScalableVectorType>(getType()))
+    if (isa<ScalableVectorType>(C->getType()))
       return false;
 
     for (unsigned i = 0, e = cast<FixedVectorType>(VTy)->getNumElements();
          i != e; ++i)
-      if (isa<UndefValue>(getAggregateElement(i)))
+      if (HasFn(C->getAggregateElement(i)))
         return true;
   }
 
   return false;
 }
 
+bool Constant::containsUndefOrPoisonElement() const {
+  return containsUndefinedElement(
+      this, [&](const auto *C) { return isa<UndefValue>(C); });
+}
+
+bool Constant::containsPoisonElement() const {
+  return containsUndefinedElement(
+      this, [&](const auto *C) { return isa<PoisonValue>(C); });
+}
+
 bool Constant::containsConstantExpression() const {
   if (auto *VTy = dyn_cast<FixedVectorType>(getType())) {
     for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i)
       if (isa<ConstantExpr>(getAggregateElement(i)))
         return true;
   }
-
   return false;
 }