[Clang/Test]: Rename enable_noundef_analysis to disable-noundef-analy…

…sis and turn it off by default

Turning on `enable_noundef_analysis` flag allows better codegen by removing freeze instructions.
I modified clang by renaming `enable_noundef_analysis` flag to `disable-noundef-analysis` and turning it off by default.

Test updates are made as a separate patch: D108453

Reviewed By: eugenis

Differential Revision: https://reviews.llvm.org/D105169

clang/include/clang/Basic/CodeGenOptions.def

@@ -64,7 +64,7 @@ CODEGENOPT(DisableLifetimeMarkers, 1, 0) ///< Don't emit any lifetime markers
 CODEGENOPT(DisableO0ImplyOptNone , 1, 0) ///< Don't annonate function with optnone at O0
 CODEGENOPT(ExperimentalStrictFloatingPoint, 1, 0) ///< Enables the new, experimental
                                                   ///< strict floating point.
-CODEGENOPT(EnableNoundefAttrs, 1, 0) ///< Enable emitting `noundef` attributes on IR call arguments and return values
+CODEGENOPT(DisableNoundefAttrs, 1, 0) ///< Disable emitting `noundef` attributes on IR call arguments and return values
 CODEGENOPT(LegacyPassManager, 1, 0) ///< Use the legacy pass manager.
 CODEGENOPT(DebugPassManager, 1, 0) ///< Prints debug information for the new
                                    ///< pass manager.

clang/include/clang/Driver/Options.td

@@ -5314,9 +5314,9 @@ def disable_free : Flag<["-"], "disable-free">,
 def clear_ast_before_backend : Flag<["-"], "clear-ast-before-backend">,
   HelpText<"Clear the Clang AST before running backend code generation">,
   MarshallingInfoFlag<CodeGenOpts<"ClearASTBeforeBackend">>;
-def enable_noundef_analysis : Flag<["-"], "enable-noundef-analysis">, Group<f_Group>,
-  HelpText<"Enable analyzing function argument and return types for mandatory definedness">,
-  MarshallingInfoFlag<CodeGenOpts<"EnableNoundefAttrs">>;
+def disable_noundef_analysis : Flag<["-"], "disable-noundef-analysis">, Group<f_Group>,
+  HelpText<"Disable analyzing function argument and return types for mandatory definedness">,
+  MarshallingInfoFlag<CodeGenOpts<"DisableNoundefAttrs">>;
 def discard_value_names : Flag<["-"], "discard-value-names">,
   HelpText<"Discard value names in LLVM IR">,
   MarshallingInfoFlag<CodeGenOpts<"DiscardValueNames">>;

clang/lib/CodeGen/CGCall.cpp

@@ -2255,7 +2255,7 @@ void CodeGenModule::ConstructAttributeList(
                      getLangOpts().Sanitize.has(SanitizerKind::Return);
 
   // Determine if the return type could be partially undef
-  if (CodeGenOpts.EnableNoundefAttrs && HasStrictReturn) {
+  if (!CodeGenOpts.DisableNoundefAttrs && HasStrictReturn) {
     if (!RetTy->isVoidType() && RetAI.getKind() != ABIArgInfo::Indirect &&
         DetermineNoUndef(RetTy, getTypes(), DL, RetAI))
       RetAttrs.addAttribute(llvm::Attribute::NoUndef);
@@ -2390,7 +2390,7 @@ void CodeGenModule::ConstructAttributeList(
 
     // Decide whether the argument we're handling could be partially undef
     bool ArgNoUndef = DetermineNoUndef(ParamType, getTypes(), DL, AI);
-    if (CodeGenOpts.EnableNoundefAttrs && ArgNoUndef)
+    if (!CodeGenOpts.DisableNoundefAttrs && ArgNoUndef)
       Attrs.addAttribute(llvm::Attribute::NoUndef);
 
     // 'restrict' -> 'noalias' is done in EmitFunctionProlog when we