[llvm] [TableGen] Simplify insertBits (NFC) (PR #137538)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/137538

We can use "constexpr if" to combine the two variants of functions.


>From d745eb89d8e8059ebb75f1e7a47f3b3fee9c6103 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Sun, 27 Apr 2025 10:52:42 -0700
Subject: [PATCH] [TableGen] Simplify insertBits (NFC)

We can use "constexpr if" to combine the two variants of functions.
---
 llvm/utils/TableGen/DecoderEmitter.cpp | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/llvm/utils/TableGen/DecoderEmitter.cpp b/llvm/utils/TableGen/DecoderEmitter.cpp
index 415fe13f87547..f0f07dfce4abb 100644
--- a/llvm/utils/TableGen/DecoderEmitter.cpp
+++ b/llvm/utils/TableGen/DecoderEmitter.cpp
@@ -2145,16 +2145,14 @@ static void emitInsertBits(formatted_raw_ostream &OS) {
 // Helper function for inserting bits extracted from an encoded instruction into
 // a field.
 template <typename InsnType>
-static std::enable_if_t<std::is_integral<InsnType>::value>
-insertBits(InsnType &field, InsnType bits, unsigned startBit, unsigned numBits) {
-  assert(startBit + numBits <= sizeof field * 8);
-  field |= (InsnType)bits << startBit;
-}
-
-template <typename InsnType>
-static std::enable_if_t<!std::is_integral<InsnType>::value>
-insertBits(InsnType &field, uint64_t bits, unsigned startBit, unsigned numBits) {
-  field.insertBits(bits, startBit, numBits);
+static void insertBits(InsnType &field, InsnType bits, unsigned startBit,
+                       unsigned numBits) {
+  if constexpr (std::is_integral<InsnType>::value) {
+    assert(startBit + numBits <= sizeof field * 8);
+    field |= (InsnType)bits << startBit;
+  } else {
+    field.insertBits(bits, startBit, numBits);
+  }
 }
 )";
 }