[llvm] [llvm][ARM]Add widen strings pass (PR #107120)

[David Green via llvm-commits]

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@@ -2029,6 +2031,145 @@ OptimizeFunctions(Module &M,
   return Changed;
 }
 
+static bool IsCharArray(Type *t) {
+  const unsigned int CHAR_BIT_SIZE = 8;
+  return t && t->isArrayTy() && t->getArrayElementType()->isIntegerTy() &&
+         t->getArrayElementType()->getIntegerBitWidth() == CHAR_BIT_SIZE;
+}
+
+static bool
+tryWidenGlobalStrings(Function &F,
+                      function_ref<TargetTransformInfo &(Function &)> GetTTI) {
+  bool changed = false;
+
+  for (Function::iterator b = F.begin(); b != F.end(); ++b) {
+    for (BasicBlock::iterator i = b->begin(); i != b->end(); ++i) {
+      CallInst *CI = dyn_cast<CallInst>(i);
+      if (!CI) {
+        continue;
+      }
+
+      TargetTransformInfo &TTI = GetTTI(F);
+
+      Function *CallMemcpy = CI->getCalledFunction();
+      // find out if the current call instruction is a call to llvm memcpy
+      // intrinsics
+      if (CallMemcpy == NULL || !CallMemcpy->isIntrinsic() ||
+          CallMemcpy->getIntrinsicID() != Intrinsic::memcpy) {
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davemgreen wrote:

Can this use `TLI->getLibFunc(*CI, Func)` and check it is LibFunc_memcpy?

https://github.com/llvm/llvm-project/pull/107120