[PATCH] D69960: [ConstantRange] Add `ushl_sat()`/`sshl_sat()` methods.

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri updated this revision to Diff 228295.
lebedev.ri marked 2 inline comments as done.
lebedev.ri added a comment.

Cleanup `sshl_sat()` with ternaries as suggested.

In D69960#1737565 <https://reviews.llvm.org/D69960#1737565>, @nikic wrote:

> > Unlike ConstantRange::shl(), these are precise.
>
> At least when modelling the APInt semantics. If we treat too large shifts as poison, then we could produce empty sets in more cases.


Yeah, i think this might be a good thing to do, but later, more globally.

> But this seems like a reasonable starting point...




Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D69960/new/

https://reviews.llvm.org/D69960

Files:
  llvm/include/llvm/IR/ConstantRange.h
  llvm/lib/IR/ConstantRange.cpp
  llvm/unittests/IR/ConstantRangeTest.cpp


Index: llvm/unittests/IR/ConstantRangeTest.cpp
===================================================================
--- llvm/unittests/IR/ConstantRangeTest.cpp
+++ llvm/unittests/IR/ConstantRangeTest.cpp
@@ -2217,6 +2217,14 @@
       });
 }
 
+TEST_F(ConstantRangeTest, UShlSat) {
+  TestUnsignedBinOpExhaustive(
+      [](const ConstantRange &CR1, const ConstantRange &CR2) {
+        return CR1.ushl_sat(CR2);
+      },
+      [](const APInt &N1, const APInt &N2) { return N1.ushl_sat(N2); });
+}
+
 TEST_F(ConstantRangeTest, SAddSat) {
   TestSignedBinOpExhaustive(
       [](const ConstantRange &CR1, const ConstantRange &CR2) {
@@ -2237,6 +2245,14 @@
       });
 }
 
+TEST_F(ConstantRangeTest, SShlSat) {
+  TestSignedBinOpExhaustive(
+      [](const ConstantRange &CR1, const ConstantRange &CR2) {
+        return CR1.sshl_sat(CR2);
+      },
+      [](const APInt &N1, const APInt &N2) { return N1.sshl_sat(N2); });
+}
+
 TEST_F(ConstantRangeTest, Abs) {
   unsigned Bits = 4;
   EnumerateConstantRanges(Bits, [&](const ConstantRange &CR) {
Index: llvm/lib/IR/ConstantRange.cpp
===================================================================
--- llvm/lib/IR/ConstantRange.cpp
+++ llvm/lib/IR/ConstantRange.cpp
@@ -1333,6 +1333,26 @@
   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();
Index: llvm/include/llvm/IR/ConstantRange.h
===================================================================
--- llvm/include/llvm/IR/ConstantRange.h
+++ llvm/include/llvm/IR/ConstantRange.h
@@ -434,6 +434,14 @@
   /// Perform a signed saturating subtraction of two constant ranges.
   ConstantRange ssub_sat(const ConstantRange &Other) const;
 
+  /// Perform an unsigned saturating left shift of this constant range by a
+  /// value in \p Other.
+  ConstantRange ushl_sat(const ConstantRange &Other) const;
+
+  /// Perform a signed saturating left shift of this constant range by a
+  /// value in \p Other.
+  ConstantRange sshl_sat(const ConstantRange &Other) const;
+
   /// Return a new range that is the logical not of the current set.
   ConstantRange inverse() const;
 


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