[PATCH] D76453: [ConstantRange] Add initial support for binaryXor.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
fhahn added reviewers: nikic, spatel, lebedev.ri.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.

The initial implementation just delegates to APInt's implementation of
XOR for single element ranges and conservatively returns the full set
otherwise.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D76453

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
@@ -2317,4 +2317,20 @@
   EXPECT_EQ(64u, IntToPtr.getBitWidth());
   EXPECT_TRUE(IntToPtr.isFullSet());
 }
+
+TEST_F(ConstantRangeTest, binaryXor) {
+  // Single element ranges.
+  ConstantRange R16(APInt(8, 16));
+  ConstantRange R20(APInt(8, 20));
+  EXPECT_EQ(*R16.binaryXor(R16).getSingleElement(), APInt(8, 0));
+  EXPECT_EQ(*R16.binaryXor(R20).getSingleElement(), APInt(8, 16 ^ 20));
+
+  // Ranges with more than a single element. Handled conservatively for now.
+  ConstantRange R16_35(APInt(8, 16), APInt(8, 35));
+  ConstantRange R0_99(APInt(8, 0), APInt(8, 99));
+  EXPECT_TRUE(R16_35.binaryXor(R16_35).isFullSet());
+  EXPECT_TRUE(R16_35.binaryXor(R0_99).isFullSet());
+  EXPECT_TRUE(R0_99.binaryXor(R16_35).isFullSet());
+}
+
 }  // anonymous namespace
Index: llvm/lib/IR/ConstantRange.cpp
===================================================================
--- llvm/lib/IR/ConstantRange.cpp
+++ llvm/lib/IR/ConstantRange.cpp
@@ -802,6 +802,8 @@
     return binaryAnd(Other);
   case Instruction::Or:
     return binaryOr(Other);
+  case Instruction::Xor:
+    return binaryXor(Other);
   // Note: floating point operations applied to abstract ranges are just
   // ideal integer operations with a lossy representation
   case Instruction::FAdd:
@@ -1219,6 +1221,18 @@
   return getNonEmpty(std::move(umax), APInt::getNullValue(getBitWidth()));
 }
 
+ConstantRange ConstantRange::binaryXor(const ConstantRange &Other) const {
+  if (isEmptySet() || Other.isEmptySet())
+    return getEmpty();
+
+  // Use APInt's implementation of XOR for single element ranges.
+  if (isSingleElement() && Other.isSingleElement())
+    return {*getSingleElement() ^ *Other.getSingleElement()};
+
+  // TODO: replace this with something less conservative
+  return getFull();
+}
+
 ConstantRange
 ConstantRange::shl(const ConstantRange &Other) const {
   if (isEmptySet() || Other.isEmptySet())
Index: llvm/include/llvm/IR/ConstantRange.h
===================================================================
--- llvm/include/llvm/IR/ConstantRange.h
+++ llvm/include/llvm/IR/ConstantRange.h
@@ -409,6 +409,10 @@
   /// from a binary-or of a value in this range by a value in \p Other.
   ConstantRange binaryOr(const ConstantRange &Other) const;
 
+  /// Return a new range representing the possible values resulting
+  /// from a binary-xor of a value in this range by a value in \p Other.
+  ConstantRange binaryXor(const ConstantRange &Other) const;
+
   /// Return a new range representing the possible values resulting
   /// from a left shift of a value in this range by a value in \p Other.
   /// TODO: This isn't fully implemented yet.


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