[llvm] [APInt] remove getClearedMemory and improve slow initialization (PR #106945)

[Nikita Popov via llvm-commits]

================
@@ -93,7 +88,7 @@ void APInt::initFromArray(ArrayRef<uint64_t> bigVal) {
     U.VAL = bigVal[0];
   else {
     // Get memory, cleared to 0
-    U.pVal = getClearedMemory(getNumWords());
+    U.pVal = new WordType[getNumWords()]();
----------------
nikic wrote:

Similar here. If bigVal.size() is smaller than getNumWords() you will not initialize some words.

https://github.com/llvm/llvm-project/pull/106945