[llvm] r193694 - make ConstantRange::signExtend() optimal

[Nuno Lopes]

Author: nlopes
Date: Wed Oct 30 10:36:50 2013
New Revision: 193694

URL: http://llvm.org/viewvc/llvm-project?rev=193694&view=rev
Log:
make ConstantRange::signExtend() optimal
the case [x, INT_MIN) was not handled optimally

Modified:
    llvm/trunk/lib/Support/ConstantRange.cpp
    llvm/trunk/unittests/Support/ConstantRangeTest.cpp

Modified: llvm/trunk/lib/Support/ConstantRange.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/ConstantRange.cpp?rev=193694&r1=193693&r2=193694&view=diff
==============================================================================
--- llvm/trunk/lib/Support/ConstantRange.cpp (original)
+++ llvm/trunk/lib/Support/ConstantRange.cpp Wed Oct 30 10:36:50 2013
@@ -445,6 +445,11 @@ ConstantRange ConstantRange::signExtend(
 
   unsigned SrcTySize = getBitWidth();
   assert(SrcTySize < DstTySize && "Not a value extension");
+
+  // special case: [X, INT_MIN) -- not really wrapping around
+  if (Upper == APInt::getHighBitsSet(SrcTySize, 1))
+    return ConstantRange(Lower.sext(DstTySize), Upper.zext(DstTySize));
+
   if (isFullSet() || isSignWrappedSet()) {
     return ConstantRange(APInt::getHighBitsSet(DstTySize,DstTySize-SrcTySize+1),
                          APInt::getLowBitsSet(DstTySize, SrcTySize-1) + 1);

Modified: llvm/trunk/unittests/Support/ConstantRangeTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/ConstantRangeTest.cpp?rev=193694&r1=193693&r2=193694&view=diff
==============================================================================
--- llvm/trunk/unittests/Support/ConstantRangeTest.cpp (original)
+++ llvm/trunk/unittests/Support/ConstantRangeTest.cpp Wed Oct 30 10:36:50 2013
@@ -216,6 +216,9 @@ TEST_F(ConstantRangeTest, SExt) {
 
   EXPECT_EQ(ConstantRange(APInt(8, 120), APInt(8, 140)).signExtend(16),
             ConstantRange(APInt(16, -128), APInt(16, 128)));
+
+  EXPECT_EQ(ConstantRange(APInt(16, 0x0200), APInt(16, 0x8000)).signExtend(19),
+            ConstantRange(APInt(19, 0x0200), APInt(19, 0x8000)));
 }
 
 TEST_F(ConstantRangeTest, IntersectWith) {