[PATCH] D57983: [ConstantRange] Shl of ConstantRanges considers full-set shifting to last bit position

[Marcello Maggioni via Phabricator via llvm-commits]

kariddi updated this revision to Diff 193827.
kariddi added a comment.

Hi Nikita, thanks for the review. I updated the patch based on your comment.

Let me know if that's ok for you now.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D57983/new/

https://reviews.llvm.org/D57983

Files:
  lib/IR/ConstantRange.cpp
  unittests/IR/ConstantRangeTest.cpp


Index: unittests/IR/ConstantRangeTest.cpp
===================================================================
--- unittests/IR/ConstantRangeTest.cpp
+++ unittests/IR/ConstantRangeTest.cpp
@@ -704,6 +704,7 @@
 }
 
 TEST_F(ConstantRangeTest, Shl) {
+  ConstantRange Some2(APInt(16, 0xfff), APInt(16, 0x8000));
   EXPECT_EQ(Full.shl(Full), Full);
   EXPECT_EQ(Full.shl(Empty), Empty);
   EXPECT_EQ(Full.shl(One), Full);    // TODO: [0, (-1 << 0xa) + 1)
@@ -720,6 +721,9 @@
   EXPECT_EQ(Some.shl(Some), Full);   // TODO: [0xa << 0xa, 0xfc01)
   EXPECT_EQ(Some.shl(Wrap), Full);   // TODO: [0xa, 0x7ff << 0x5 + 1)
   EXPECT_EQ(Wrap.shl(Wrap), Full);
+  EXPECT_EQ(
+      Some2.shl(ConstantRange(APInt(16, 0x1))),
+      ConstantRange(APInt(16, 0xfff << 0x1), APInt(16, 0x7fff << 0x1) + 1));
 }
 
 TEST_F(ConstantRangeTest, Lshr) {
Index: lib/IR/ConstantRange.cpp
===================================================================
--- lib/IR/ConstantRange.cpp
+++ lib/IR/ConstantRange.cpp
@@ -1006,8 +1006,12 @@
   APInt max = getUnsignedMax();
   APInt Other_umax = Other.getUnsignedMax();
 
+  // If we are shifting by maximum amount of
+  // zero return return the original range.
+  if (Other_umax.isNullValue())
+    return *this;
   // there's overflow!
-  if (Other_umax.uge(max.countLeadingZeros()))
+  if (Other_umax.ugt(max.countLeadingZeros()))
     return getFull();
 
   // FIXME: implement the other tricky cases


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