[PATCH] D132813: [Support] Simplify isInt and isUInt with constexpr if (NFC)

[Kazu Hirata via Phabricator via llvm-commits]

kazu created this revision.
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kazu requested review of this revision.
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Herald added a subscriber: llvm-commits.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D132813

Files:
  llvm/include/llvm/Support/MathExtras.h


Index: llvm/include/llvm/Support/MathExtras.h
===================================================================
--- llvm/include/llvm/Support/MathExtras.h
+++ llvm/include/llvm/Support/MathExtras.h
@@ -358,17 +358,16 @@
 
 /// Checks if an integer fits into the given bit width.
 template <unsigned N> constexpr inline bool isInt(int64_t x) {
-  return N >= 64 || (-(INT64_C(1)<<(N-1)) <= x && x < (INT64_C(1)<<(N-1)));
-}
-// Template specializations to get better code for common cases.
-template <> constexpr inline bool isInt<8>(int64_t x) {
-  return static_cast<int8_t>(x) == x;
-}
-template <> constexpr inline bool isInt<16>(int64_t x) {
-  return static_cast<int16_t>(x) == x;
-}
-template <> constexpr inline bool isInt<32>(int64_t x) {
-  return static_cast<int32_t>(x) == x;
+  if constexpr (N == 8)
+    return static_cast<int8_t>(x) == x;
+  if constexpr (N == 16)
+    return static_cast<int16_t>(x) == x;
+  if constexpr (N == 32)
+    return static_cast<int32_t>(x) == x;
+  if constexpr (N < 64)
+    return -(INT64_C(1) << (N - 1)) <= x && x < (INT64_C(1) << (N - 1));
+  (void)x; // MSVC v19.25 warns that x is unused.
+  return true;
 }
 
 /// Checks if a signed integer is an N bit number shifted left by S.
@@ -381,34 +380,20 @@
 }
 
 /// Checks if an unsigned integer fits into the given bit width.
-///
-/// This is written as two functions rather than as simply
-///
-///   return N >= 64 || X < (UINT64_C(1) << N);
-///
-/// to keep MSVC from (incorrectly) warning on isUInt<64> that we're shifting
-/// left too many places.
-template <unsigned N>
-constexpr inline std::enable_if_t<(N < 64), bool> isUInt(uint64_t X) {
+template <unsigned N> constexpr inline bool isUInt(uint64_t x) {
   static_assert(N > 0, "isUInt<0> doesn't make sense");
-  return X < (UINT64_C(1) << (N));
-}
-template <unsigned N>
-constexpr inline std::enable_if_t<N >= 64, bool> isUInt(uint64_t) {
+  if constexpr (N == 8)
+    return static_cast<uint8_t>(x) == x;
+  if constexpr (N == 16)
+    return static_cast<uint16_t>(x) == x;
+  if constexpr (N == 32)
+    return static_cast<uint32_t>(x) == x;
+  if constexpr (N < 64)
+    return x < (UINT64_C(1) << (N));
+  (void)x; // MSVC v19.25 warns that x is unused.
   return true;
 }
 
-// Template specializations to get better code for common cases.
-template <> constexpr inline bool isUInt<8>(uint64_t x) {
-  return static_cast<uint8_t>(x) == x;
-}
-template <> constexpr inline bool isUInt<16>(uint64_t x) {
-  return static_cast<uint16_t>(x) == x;
-}
-template <> constexpr inline bool isUInt<32>(uint64_t x) {
-  return static_cast<uint32_t>(x) == x;
-}
-
 /// Checks if a unsigned integer is an N bit number shifted left by S.
 template <unsigned N, unsigned S>
 constexpr inline bool isShiftedUInt(uint64_t x) {


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