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[APInt] Fix rotl/rotr when the shift amount is greater than the total bit width. 

Review: https://reviews.llvm.org/D27749
llvm-svn: 294295
This commit is contained in:
Joey Gouly 2017-02-07 11:58:22 +00:00
parent d588b0f525
commit 51c0ae5e51
2 changed files with 67 additions and 4 deletions
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17
llvm/lib/Support/APInt.cpp
View File

@ -1252,8 +1252,21 @@ APInt APInt::shlSlowCase(unsigned shiftAmt) const {
return Result;
}
// Calculate the rotate amount modulo the bit width.
static unsigned rotateModulo(unsigned BitWidth, const APInt &rotateAmt) {
unsigned rotBitWidth = rotateAmt.getBitWidth();
APInt rot = rotateAmt;
if (rotBitWidth < BitWidth) {
// Extend the rotate APInt, so that the urem doesn't divide by 0.
// e.g. APInt(1, 32) would give APInt(1, 0).
rot = rotateAmt.zext(BitWidth);
}
rot = rot.urem(APInt(rot.getBitWidth(), BitWidth));
return rot.getLimitedValue(BitWidth);
}
APInt APInt::rotl(const APInt &rotateAmt) const {
return rotl((unsigned)rotateAmt.getLimitedValue(BitWidth));
return rotl(rotateModulo(BitWidth, rotateAmt));
}
APInt APInt::rotl(unsigned rotateAmt) const {
@ -1264,7 +1277,7 @@ APInt APInt::rotl(unsigned rotateAmt) const {
}
APInt APInt::rotr(const APInt &rotateAmt) const {
return rotr((unsigned)rotateAmt.getLimitedValue(BitWidth));
return rotr(rotateModulo(BitWidth, rotateAmt));
}
APInt APInt::rotr(unsigned rotateAmt) const {

54
llvm/unittests/ADT/APIntTest.cpp
View File

@ -1060,6 +1060,29 @@ TEST(APIntTest, Rotate) {
EXPECT_EQ(APInt(8, 1), APInt(8, 16).rotl(4));
EXPECT_EQ(APInt(8, 16), APInt(8, 16).rotl(8));
EXPECT_EQ(APInt(32, 2), APInt(32, 1).rotl(33));
EXPECT_EQ(APInt(32, 2), APInt(32, 1).rotl(APInt(32, 33)));
EXPECT_EQ(APInt(32, 2), APInt(32, 1).rotl(33));
EXPECT_EQ(APInt(32, 2), APInt(32, 1).rotl(APInt(32, 33)));
EXPECT_EQ(APInt(32, 2), APInt(32, 1).rotl(APInt(33, 33)));
EXPECT_EQ(APInt(32, (1 << 8)), APInt(32, 1).rotl(APInt(32, 40)));
EXPECT_EQ(APInt(32, (1 << 30)), APInt(32, 1).rotl(APInt(31, 30)));
EXPECT_EQ(APInt(32, (1 << 31)), APInt(32, 1).rotl(APInt(31, 31)));
EXPECT_EQ(APInt(32, 1), APInt(32, 1).rotl(APInt(1, 0)));
EXPECT_EQ(APInt(32, 2), APInt(32, 1).rotl(APInt(1, 1)));
EXPECT_EQ(APInt(32, 16), APInt(32, 1).rotl(APInt(3, 4)));
EXPECT_EQ(APInt(32, 1), APInt(32, 1).rotl(APInt(64, 64)));
EXPECT_EQ(APInt(32, 2), APInt(32, 1).rotl(APInt(64, 65)));
EXPECT_EQ(APInt(7, 24), APInt(7, 3).rotl(APInt(7, 3)));
EXPECT_EQ(APInt(7, 24), APInt(7, 3).rotl(APInt(7, 10)));
EXPECT_EQ(APInt(7, 24), APInt(7, 3).rotl(APInt(5, 10)));
EXPECT_EQ(APInt(7, 6), APInt(7, 3).rotl(APInt(12, 120)));
EXPECT_EQ(APInt(8, 16), APInt(8, 16).rotr(0));
EXPECT_EQ(APInt(8, 8), APInt(8, 16).rotr(1));
EXPECT_EQ(APInt(8, 4), APInt(8, 16).rotr(2));
@ -1072,9 +1095,36 @@ TEST(APIntTest, Rotate) {
EXPECT_EQ(APInt(8, 16), APInt(8, 1).rotr(4));
EXPECT_EQ(APInt(8, 1), APInt(8, 1).rotr(8));
APInt Big(256, "00004000800000000000000000003fff8000000000000000", 16);
APInt Rot(256, "3fff80000000000000000000000000000000000040008000", 16);
EXPECT_EQ(APInt(32, (1 << 31)), APInt(32, 1).rotr(33));
EXPECT_EQ(APInt(32, (1 << 31)), APInt(32, 1).rotr(APInt(32, 33)));
EXPECT_EQ(APInt(32, (1 << 31)), APInt(32, 1).rotr(33));
EXPECT_EQ(APInt(32, (1 << 31)), APInt(32, 1).rotr(APInt(32, 33)));
EXPECT_EQ(APInt(32, (1 << 31)), APInt(32, 1).rotr(APInt(33, 33)));
EXPECT_EQ(APInt(32, (1 << 24)), APInt(32, 1).rotr(APInt(32, 40)));
EXPECT_EQ(APInt(32, (1 << 2)), APInt(32, 1).rotr(APInt(31, 30)));
EXPECT_EQ(APInt(32, (1 << 1)), APInt(32, 1).rotr(APInt(31, 31)));
EXPECT_EQ(APInt(32, 1), APInt(32, 1).rotr(APInt(1, 0)));
EXPECT_EQ(APInt(32, (1 << 31)), APInt(32, 1).rotr(APInt(1, 1)));
EXPECT_EQ(APInt(32, (1 << 28)), APInt(32, 1).rotr(APInt(3, 4)));
EXPECT_EQ(APInt(32, 1), APInt(32, 1).rotr(APInt(64, 64)));
EXPECT_EQ(APInt(32, (1 << 31)), APInt(32, 1).rotr(APInt(64, 65)));
EXPECT_EQ(APInt(7, 48), APInt(7, 3).rotr(APInt(7, 3)));
EXPECT_EQ(APInt(7, 48), APInt(7, 3).rotr(APInt(7, 10)));
EXPECT_EQ(APInt(7, 48), APInt(7, 3).rotr(APInt(5, 10)));
EXPECT_EQ(APInt(7, 65), APInt(7, 3).rotr(APInt(12, 120)));
APInt Big(256, "00004000800000000000000000003fff8000000000000003", 16);
APInt Rot(256, "3fff80000000000000030000000000000000000040008000", 16);
EXPECT_EQ(Rot, Big.rotr(144));
EXPECT_EQ(APInt(32, 8), APInt(32, 1).rotl(Big));
EXPECT_EQ(APInt(32, (1 << 29)), APInt(32, 1).rotr(Big));
}
TEST(APIntTest, Splat) {