MathExtras: avoid unnecessarily widening types (#95426)

Several multi-argument functions unnecessarily widen types beyond the
argument types. Template'ize the functions, and use std::common_type_t
to avoid this, hence optimizing the functions. A requirement of this
patch is to change the overflow behavior of alignTo to only overflow
when the result isn't representable in the return type.

1 files changed, 16 insertions, 2 deletions

diff --git a/llvm/unittests/Support/MathExtrasTest.cpp b/llvm/unittests/Support/MathExtrasTest.cpp
index bd09bab..a557b61 100644
--- a/llvm/unittests/Support/MathExtrasTest.cpp
+++ b/llvm/unittests/Support/MathExtrasTest.cpp
@@ -189,8 +189,13 @@ TEST(MathExtras, AlignTo) {
   EXPECT_EQ(8u, alignTo(5, 8));
   EXPECT_EQ(24u, alignTo(17, 8));
   EXPECT_EQ(0u, alignTo(~0LL, 8));
-  EXPECT_EQ(static_cast<uint64_t>(std::numeric_limits<uint32_t>::max()) + 1,
-            alignTo(std::numeric_limits<uint32_t>::max(), 2));
+  EXPECT_EQ(8u, alignTo(5ULL, 8ULL));
+
+  EXPECT_EQ(8u, alignTo<8>(5));
+  EXPECT_EQ(24u, alignTo<8>(17));
+  EXPECT_EQ(0u, alignTo<8>(~0LL));
+  EXPECT_EQ(254u,
+            alignTo<static_cast<uint8_t>(127)>(static_cast<uint8_t>(200)));
 
   EXPECT_EQ(7u, alignTo(5, 8, 7));
   EXPECT_EQ(17u, alignTo(17, 8, 1));
@@ -198,12 +203,21 @@ TEST(MathExtras, AlignTo) {
   EXPECT_EQ(552u, alignTo(321, 255, 42));
   EXPECT_EQ(std::numeric_limits<uint32_t>::max(),
             alignTo(std::numeric_limits<uint32_t>::max(), 2, 1));
+
+  // Overflow.
+  EXPECT_EQ(0u, alignTo(static_cast<uint8_t>(200), static_cast<uint8_t>(128)));
+  EXPECT_EQ(0u, alignTo<static_cast<uint8_t>(128)>(static_cast<uint8_t>(200)));
+  EXPECT_EQ(0u, alignTo(static_cast<uint8_t>(200), static_cast<uint8_t>(128),
+                        static_cast<uint8_t>(0)));
+  EXPECT_EQ(0u, alignTo(std::numeric_limits<uint32_t>::max(), 2));
 }
 
 TEST(MathExtras, AlignToPowerOf2) {
+  EXPECT_EQ(0u, alignToPowerOf2(0u, 8));
   EXPECT_EQ(8u, alignToPowerOf2(5, 8));
   EXPECT_EQ(24u, alignToPowerOf2(17, 8));
   EXPECT_EQ(0u, alignToPowerOf2(~0LL, 8));
+  EXPECT_EQ(240u, alignToPowerOf2(240, 16));
   EXPECT_EQ(static_cast<uint64_t>(std::numeric_limits<uint32_t>::max()) + 1,
             alignToPowerOf2(std::numeric_limits<uint32_t>::max(), 2));
 }