[llvm] Enable logf128 constant folding for hosts with 128bit long double (PR #104929)

[David Green via llvm-commits]

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@@ -1883,6 +1875,12 @@ class [[nodiscard]] APInt {
   /// Returns whether this instance allocated memory.
   bool needsCleanup() const { return !isSingleWord(); }
 
+  /// Get the word corresponding to a bit position
+  /// \returns the corresponding word for the specified bit position.
+  uint64_t getWord(unsigned bitPosition) const {
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davemgreen wrote:

Would it be possible to avoid adding this by using `LowHalf == APInt.getWord(0) == APint.trunc(64).getZExtValue()` and `HighHalf == APInt.getWord(64) == APInt.lshr(64).trunc(64).getZExtValue()`

https://github.com/llvm/llvm-project/pull/104929