make ConstantRange::zeroExtend() optimal

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160643 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Support/ConstantRange.cpp b/lib/Support/ConstantRange.cpp
index a3f2297596374b5f6a212b986aad12f9a2ae9624..720ef36c4640f4812c35c65faf390c925d238329 100644 (file)
--- a/lib/Support/ConstantRange.cpp
+++ b/lib/Support/ConstantRange.cpp
@@ -427,9 +427,13 @@ ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
 
   unsigned SrcTySize = getBitWidth();
   assert(SrcTySize < DstTySize && "Not a value extension");
 
   unsigned SrcTySize = getBitWidth();
   assert(SrcTySize < DstTySize && "Not a value extension");

-  if (isFullSet() || isWrappedSet())
+  if (isFullSet() || isWrappedSet()) {

     // Change into [0, 1 << src bit width)
     // 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));
 }
 
   return ConstantRange(Lower.zext(DstTySize), Upper.zext(DstTySize));
 }

diff --git a/unittests/Support/ConstantRangeTest.cpp b/unittests/Support/ConstantRangeTest.cpp
index 7d4055f889f55cfab10f15b1467fc45ddf3b472c..263f93c9ff373b65829a52f3486ab731004e517e 100644 (file)
--- a/unittests/Support/ConstantRangeTest.cpp
+++ b/unittests/Support/ConstantRangeTest.cpp
@@ -193,6 +193,10 @@ TEST_F(ConstantRangeTest, ZExt) {
   EXPECT_EQ(ZSome, ConstantRange(Some.getLower().zext(20),
                                  Some.getUpper().zext(20)));
   EXPECT_EQ(ZWrap, ConstantRange(APInt(20, 0), APInt(20, 0x10000)));
   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) {
 }
 
 TEST_F(ConstantRangeTest, SExt) {