[llvm] [BOLT] Create .text.warm for 3-way splitting (PR #73863)

[Maksim Panchenko via llvm-commits]

================
@@ -4423,9 +4436,15 @@ void RewriteInstance::updateELFSymbolTable(
            Function.getLayout().getSplitFragments()) {
         if (FF.getAddress()) {
           ELFSymTy NewColdSym = FunctionSymbol;
-          const SmallString<256> SymbolName = formatv(
-              "{0}.cold.{1}", cantFail(FunctionSymbol.getName(StringSection)),
-              FF.getFragmentNum().get() - 1);
+          SmallString<256> SymbolName;
+          if (BC->HasWarmSection)
+            SymbolName = formatv(
+                "{0}.{1}", cantFail(FunctionSymbol.getName(StringSection)),
+                FF.getFragmentNum() == FragmentNum::warm() ? "warm" : "cold");
+          else
+            SymbolName = formatv(
+                "{0}.cold.{1}", cantFail(FunctionSymbol.getName(StringSection)),
+                FF.getFragmentNum().get() - 1);
----------------
maksfb wrote:

Let's factor this code out into a separate helper function.

https://github.com/llvm/llvm-project/pull/73863