commit eb9d2755b20f9874b5cf77d77d7b5692628d93ea
author Nuno Lopes <nunoplopes@sapo.pt> Mon Jul 23 20:33:29 2012 +0000
committer Nuno Lopes <nunoplopes@sapo.pt> Mon Jul 23 20:33:29 2012 +0000
tree 94737ce65cd8e6503db3a6a89245dd95b5067218
parent 1feac1cef9bba99d0832eac9a58084cb90c669d8

make ConstantRange::zeroExtend() optimal

llvm-svn: 160643

llvm/lib/Support/ConstantRange.cpp

diff --git a/llvm/lib/Support/ConstantRange.cpp b/llvm/lib/Support/ConstantRange.cpp
index a3f2297..720ef36 100644
--- a/llvm/lib/Support/ConstantRange.cpp
+++ b/llvm/lib/Support/ConstantRange.cpp
@@ -427,9 +427,13 @@
 
   unsigned SrcTySize = getBitWidth();
   assert(SrcTySize < DstTySize && "Not a value extension");
-  if (isFullSet() || isWrappedSet())
+  if (isFullSet() || isWrappedSet()) {
     // Change into [0, 1 << src bit width)
-    return ConstantRange(APInt(DstTySize,0), APInt(DstTySize,1).shl(SrcTySize));
+    APInt LowerExt(DstTySize, 0);
+    if (!Upper) // special case: [X, 0) -- not really wrapping around
+      LowerExt = Lower.zext(DstTySize);
+    return ConstantRange(LowerExt, APInt(DstTySize, 1).shl(SrcTySize));
+  }
 
   return ConstantRange(Lower.zext(DstTySize), Upper.zext(DstTySize));
 }

llvm/unittests/Support/ConstantRangeTest.cpp

diff --git a/llvm/unittests/Support/ConstantRangeTest.cpp b/llvm/unittests/Support/ConstantRangeTest.cpp
index 7d4055f..263f93c 100644
--- a/llvm/unittests/Support/ConstantRangeTest.cpp
+++ b/llvm/unittests/Support/ConstantRangeTest.cpp
@@ -193,6 +193,10 @@
   EXPECT_EQ(ZSome, ConstantRange(Some.getLower().zext(20),
                                  Some.getUpper().zext(20)));
   EXPECT_EQ(ZWrap, ConstantRange(APInt(20, 0), APInt(20, 0x10000)));
+
+  // zext([5, 0), 3->7) = [5, 8)
+  ConstantRange FiveZero(APInt(3, 5), APInt(3, 0));
+  EXPECT_EQ(FiveZero.zeroExtend(7), ConstantRange(APInt(7, 5), APInt(7, 8)));
 }
 
 TEST_F(ConstantRangeTest, SExt) {