[PATCH] D59848: [ConstantRange] Exclude full set from isSignWrappedSet()

[Nikita Popov via Phabricator via llvm-commits]

nikic created this revision.
nikic added a reviewer: lebedev.ri.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.

Split off from D59749 <https://reviews.llvm.org/D59749>. This uses a simpler and more efficient implementation of isSignWrappedSet(), and considers full sets as non-wrapped, to be consistent with isWrappedSet(). Otherwise the behavior is unchanged.

There are currently only two users of this function and both already check for `isFullSet() || isSignWrappedSet()`, so this is not going to cause a change in overall behavior:

  lib/IR/ConstantRange.cpp:  if (isFullSet() || isSignWrappedSet()) {
  lib/Transforms/Scalar/Float2Int.cpp:        R.isFullSet() || R.isSignWrappedSet())


Repository:
  rL LLVM

https://reviews.llvm.org/D59848

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
@@ -161,7 +161,7 @@
 }
 
 TEST_F(ConstantRangeTest, SignWrapped) {
-  EXPECT_TRUE(Full.isSignWrappedSet());
+  EXPECT_FALSE(Full.isSignWrappedSet());
   EXPECT_FALSE(Empty.isSignWrappedSet());
   EXPECT_FALSE(One.isSignWrappedSet());
   EXPECT_FALSE(Some.isSignWrappedSet());
Index: llvm/lib/IR/ConstantRange.cpp
===================================================================
--- llvm/lib/IR/ConstantRange.cpp
+++ llvm/lib/IR/ConstantRange.cpp
@@ -349,8 +349,7 @@
 }
 
 bool ConstantRange::isSignWrappedSet() const {
-  return contains(APInt::getSignedMaxValue(getBitWidth())) &&
-         contains(APInt::getSignedMinValue(getBitWidth()));
+  return Lower.sgt(Upper) && !Upper.isMinSignedValue();
 }
 
 APInt ConstantRange::getSetSize() const {
Index: llvm/include/llvm/IR/ConstantRange.h
===================================================================
--- llvm/include/llvm/IR/ConstantRange.h
+++ llvm/include/llvm/IR/ConstantRange.h
@@ -167,8 +167,10 @@
   /// For example: [100, 8).
   bool isWrappedSet() const;
 
-  /// Return true if this set wraps around the INT_MIN of
-  /// its bitwidth. For example: i8 [120, 140).
+  /// Return true if this set wraps around the signed domain. Special cases:
+  ///  * Empty set: Not wrapped.
+  ///  * Full set: Not wrapped.
+  ///  * [X, SignedMin) == [X, SignedMax]: Not wrapped.
   bool isSignWrappedSet() const;
 
   /// Return true if the specified value is in the set.


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