[PATCH] D60536: [ConstantRange] [0, 1) divided by non-empty ranges is [0, 1).

[Florian Hahn via Phabricator via llvm-commits]

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

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D60536

Files:
  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
@@ -770,6 +770,10 @@
   EXPECT_EQ(Some.udiv(Some), ConstantRange(APInt(16, 0), APInt(16, 0x111)));
   EXPECT_EQ(Some.udiv(Wrap), ConstantRange(APInt(16, 0), APInt(16, 0xaaa)));
   EXPECT_EQ(Wrap.udiv(Wrap), Full);
+
+  ConstantRange Zero(APInt(16, 0));
+  EXPECT_EQ(Zero.udiv(One), Zero);
+  EXPECT_EQ(Zero.udiv(Full), Zero);
 }
 
 TEST_F(ConstantRangeTest, Shl) {
Index: llvm/lib/IR/ConstantRange.cpp
===================================================================
--- llvm/lib/IR/ConstantRange.cpp
+++ llvm/lib/IR/ConstantRange.cpp
@@ -1009,6 +1009,8 @@
 ConstantRange::udiv(const ConstantRange &RHS) const {
   if (isEmptySet() || RHS.isEmptySet() || RHS.getUnsignedMax().isNullValue())
     return getEmpty();
+  if (isSingleElement() && getSingleElement()->isNullValue())
+    return *this;
   if (RHS.isFullSet())
     return getFull();
 


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