[APInt] Add methods for saturated add and sub
This adds the sadd_sat, uadd_sat, ssub_sat, usub_sat methods for performing saturating additions and subtractions to APInt.
Split out from D54237.
Patch by: nikic (Nikita Popov)
Differential Revision: https://reviews.llvm.org/D54332
llvm-svn: 347324
diff --git a/llvm/unittests/ADT/APIntTest.cpp b/llvm/unittests/ADT/APIntTest.cpp
index 6bee61c..8b876f3 100644
--- a/llvm/unittests/ADT/APIntTest.cpp
+++ b/llvm/unittests/ADT/APIntTest.cpp
@@ -1176,6 +1176,30 @@
EXPECT_EQ(APInt(32, uint64_t(-72LL)), APInt(32, "-20", 36));
}
+TEST(APIntTest, SaturatingMath) {
+ APInt AP_10 = APInt(8, 10);
+ APInt AP_100 = APInt(8, 100);
+ APInt AP_200 = APInt(8, 200);
+
+ EXPECT_EQ(APInt(8, 200), AP_100.uadd_sat(AP_100));
+ EXPECT_EQ(APInt(8, 255), AP_100.uadd_sat(AP_200));
+ EXPECT_EQ(APInt(8, 255), APInt(8, 255).uadd_sat(APInt(8, 255)));
+
+ EXPECT_EQ(APInt(8, 110), AP_10.sadd_sat(AP_100));
+ EXPECT_EQ(APInt(8, 127), AP_100.sadd_sat(AP_100));
+ EXPECT_EQ(APInt(8, -128), (-AP_100).sadd_sat(-AP_100));
+ EXPECT_EQ(APInt(8, -128), APInt(8, -128).sadd_sat(APInt(8, -128)));
+
+ EXPECT_EQ(APInt(8, 90), AP_100.usub_sat(AP_10));
+ EXPECT_EQ(APInt(8, 0), AP_100.usub_sat(AP_200));
+ EXPECT_EQ(APInt(8, 0), APInt(8, 0).usub_sat(APInt(8, 255)));
+
+ EXPECT_EQ(APInt(8, -90), AP_10.ssub_sat(AP_100));
+ EXPECT_EQ(APInt(8, 127), AP_100.ssub_sat(-AP_100));
+ EXPECT_EQ(APInt(8, -128), (-AP_100).ssub_sat(AP_100));
+ EXPECT_EQ(APInt(8, -128), APInt(8, -128).ssub_sat(APInt(8, 127)));
+}
+
TEST(APIntTest, FromArray) {
EXPECT_EQ(APInt(32, uint64_t(1)), APInt(32, ArrayRef<uint64_t>(1)));
}