[llvm] r299243 - [APInt] Rewrite getLoBits in a way that will do one less memory allocation in the multiword case. Rewrite getHiBits to use the class method version of lshr instead of the one in APIntOps. NFCI

[Craig Topper via llvm-commits]

Author: ctopper
Date: Fri Mar 31 13:48:14 2017
New Revision: 299243

URL: http://llvm.org/viewvc/llvm-project?rev=299243&view=rev
Log:
[APInt] Rewrite getLoBits in a way that will do one less memory allocation in the multiword case. Rewrite getHiBits to use the class method version of lshr instead of the one in APIntOps. NFCI

Modified:
    llvm/trunk/lib/Support/APInt.cpp
    llvm/trunk/unittests/ADT/APIntTest.cpp

Modified: llvm/trunk/lib/Support/APInt.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/APInt.cpp?rev=299243&r1=299242&r2=299243&view=diff
==============================================================================
--- llvm/trunk/lib/Support/APInt.cpp (original)
+++ llvm/trunk/lib/Support/APInt.cpp Fri Mar 31 13:48:14 2017
@@ -724,13 +724,14 @@ bool APInt::isSplat(unsigned SplatSizeIn
 
 /// This function returns the high "numBits" bits of this APInt.
 APInt APInt::getHiBits(unsigned numBits) const {
-  return APIntOps::lshr(*this, BitWidth - numBits);
+  return this->lshr(BitWidth - numBits);
 }
 
 /// This function returns the low "numBits" bits of this APInt.
 APInt APInt::getLoBits(unsigned numBits) const {
-  return APIntOps::lshr(APIntOps::shl(*this, BitWidth - numBits),
-                        BitWidth - numBits);
+  APInt Result(getLowBitsSet(BitWidth, numBits));
+  Result &= *this;
+  return Result;
 }
 
 unsigned APInt::countLeadingZerosSlowCase() const {

Modified: llvm/trunk/unittests/ADT/APIntTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/ADT/APIntTest.cpp?rev=299243&r1=299242&r2=299243&view=diff
==============================================================================
--- llvm/trunk/unittests/ADT/APIntTest.cpp (original)
+++ llvm/trunk/unittests/ADT/APIntTest.cpp Fri Mar 31 13:48:14 2017
@@ -1958,3 +1958,21 @@ TEST(APIntTest, setAllBits) {
   EXPECT_EQ(128u, i128.countTrailingOnes());
   EXPECT_EQ(128u, i128.countPopulation());
 }
+
+TEST(APIntTest, getLoBits) {
+  APInt i32(32, 0xfa);
+  i32.setHighBits(1);
+  EXPECT_EQ(0xa, i32.getLoBits(4));
+  APInt i128(128, 0xfa);
+  i128.setHighBits(1);
+  EXPECT_EQ(0xa, i128.getLoBits(4));
+}
+
+TEST(APIntTest, getHiBits) {
+  APInt i32(32, 0xfa);
+  i32.setHighBits(2);
+  EXPECT_EQ(0xc, i32.getHiBits(4));
+  APInt i128(128, 0xfa);
+  i128.setHighBits(2);
+  EXPECT_EQ(0xc, i128.getHiBits(4));
+}