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[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 

llvm-svn: 299243
This commit is contained in:
Craig Topper 2017-03-31 18:48:14 +00:00
parent d53b5b19a9
commit e7e3560288
2 changed files with 22 additions and 3 deletions
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7
llvm/lib/Support/APInt.cpp
View File

@ -724,13 +724,14 @@ bool APInt::isSplat(unsigned SplatSizeInBits) const {
/// 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 {

18
llvm/unittests/ADT/APIntTest.cpp
View File

@ -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));
}