[NFC] Minimize noundef analysis when disabled

[kda]

Summary

Minor adjustment in order of noundef analysis to be a bit more optimal (when disabled).

[vitalybuka]

my editor recommends me to keep git titles <50 chars
Maybe something shorter with exactly the same meaning
"[NFC] Optimize noundef analysis condition"

clang/lib/CodeGen/CGCall.cpp

2382–2384

[kda]

reduce nesting

[kda]

In D117078#3238422, @vitalybuka wrote:

my editor recommends me to keep git titles <50 chars
Maybe something shorter with exactly the same meaning
"[NFC] Optimize noundef analysis condition"

Done!

clang/lib/CodeGen/CGCall.cpp

if (IRFunctionArgs.hasPaddingArg(ArgNo)) {
         ArgAttrs[IRFunctionArgs.getPaddingArgNo(ArgNo)] =
             llvm::AttributeSet::get(
                 getLLVMContext(),
                 llvm::AttrBuilder(getLLVMContext()).addAttribute(llvm::Attribute::InReg));
       }
     }
 
     // Decide whether the argument we're handling could be partially undef
-    bool ArgNoUndef = DetermineNoUndef(ParamType, getTypes(), DL, AI);
-    if (CodeGenOpts.EnableNoundefAttrs && ArgNoUndef)
+    if (CodeGenOpts.EnableNoundefAttrs &&
+        DetermineNoUndef(ParamType, getTypes(), DL, AI)) {
       Attrs.addAttribute(llvm::Attribute::NoUndef);
+    }
 
     // 'restrict' -> 'noalias' is done in EmitFunctionProlog when we
     // have the corresponding parameter variable.  It doesn't make
     // sense to do it here because parameters are so messed up.
     switch (AI.getKind()) {
     case ABIArgInfo::Extend:
       if (AI.isSignExt())
         Attrs.addAttribute(llvm::Attribute::SExt);
       else