[ConstantRange] Add `ushl_sat()`/`sshl_sat()` methods.

Summary:
To be used in `ConstantRange::shlWithNoOverflow()`,
may in future be useful for when saturating shift/mul ops are added.

Unlike `ConstantRange::shl()`, these are precise.

Reviewers: nikic, spatel, reames

Reviewed By: nikic

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69960

1 files changed, 20 insertions, 0 deletions

diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp
index 18d8e9d..63a6494 100644
--- a/llvm/lib/IR/ConstantRange.cpp
+++ b/llvm/lib/IR/ConstantRange.cpp
@@ -1333,6 +1333,26 @@ ConstantRange ConstantRange::ssub_sat(const ConstantRange &Other) const {
   return getNonEmpty(std::move(NewL), std::move(NewU));
 }
 
+ConstantRange ConstantRange::ushl_sat(const ConstantRange &Other) const {
+  if (isEmptySet() || Other.isEmptySet())
+    return getEmpty();
+
+  APInt NewL = getUnsignedMin().ushl_sat(Other.getUnsignedMin());
+  APInt NewU = getUnsignedMax().ushl_sat(Other.getUnsignedMax()) + 1;
+  return getNonEmpty(std::move(NewL), std::move(NewU));
+}
+
+ConstantRange ConstantRange::sshl_sat(const ConstantRange &Other) const {
+  if (isEmptySet() || Other.isEmptySet())
+    return getEmpty();
+
+  APInt Min = getSignedMin(), Max = getSignedMax();
+  APInt ShAmtMin = Other.getUnsignedMin(), ShAmtMax = Other.getUnsignedMax();
+  APInt NewL = Min.sshl_sat(isAllNonNegative() ? ShAmtMin : ShAmtMax);
+  APInt NewU = Max.sshl_sat(isAllNegative() ? ShAmtMin : ShAmtMax) + 1;
+  return getNonEmpty(std::move(NewL), std::move(NewU));
+}
+
 ConstantRange ConstantRange::inverse() const {
   if (isFullSet())
     return getEmpty();