[llvm-commits] [llvm] r160317 - in /llvm/trunk: lib/Support/ConstantRange.cpp unittests/Support/ConstantRangeTest.cpp

[Nuno Lopes]

Author: nlopes
Date: Mon Jul 16 15:47:16 2012
New Revision: 160317

URL: http://llvm.org/viewvc/llvm-project?rev=160317&view=rev
Log:
teach ConstantRange that zero times X is always zero

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=160317&r1=160316&r2=160317&view=diff
==============================================================================
--- llvm/trunk/lib/Support/ConstantRange.cpp (original)
+++ llvm/trunk/lib/Support/ConstantRange.cpp Mon Jul 16 15:47:16 2012
@@ -537,6 +537,12 @@
 
   if (isEmptySet() || Other.isEmptySet())
     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
+
+  // If any of the operands is zero, then the result is also zero.
+  if ((getSingleElement() && *getSingleElement() == 0) ||
+      (Other.getSingleElement() && *Other.getSingleElement() == 0))
+    return ConstantRange(APInt(getBitWidth(), 0));
+
   if (isFullSet() || Other.isFullSet())
     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 

Modified: llvm/trunk/unittests/Support/ConstantRangeTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/ConstantRangeTest.cpp?rev=160317&r1=160316&r2=160317&view=diff
==============================================================================
--- llvm/trunk/unittests/Support/ConstantRangeTest.cpp (original)
+++ llvm/trunk/unittests/Support/ConstantRangeTest.cpp Mon Jul 16 15:47:16 2012
@@ -382,6 +382,14 @@
   EXPECT_EQ(Some.multiply(Wrap), Full);
   EXPECT_EQ(Wrap.multiply(Wrap), Full);
 
+  ConstantRange Zero(APInt(16, 0));
+  EXPECT_EQ(Zero.multiply(Full), Zero);
+  EXPECT_EQ(Zero.multiply(Some), Zero);
+  EXPECT_EQ(Zero.multiply(Wrap), Zero);
+  EXPECT_EQ(Full.multiply(Zero), Zero);
+  EXPECT_EQ(Some.multiply(Zero), Zero);
+  EXPECT_EQ(Wrap.multiply(Zero), Zero);
+
   // http://llvm.org/PR4545
   EXPECT_EQ(ConstantRange(APInt(4, 1), APInt(4, 6)).multiply(
                 ConstantRange(APInt(4, 6), APInt(4, 2))),