Revert "[Clang] __has_builtin should return false for aux triple builtins (#121839) (#124626)

This reverts commit 1c28b92.

Breaks CUDA on ARM, see
[here](#121839 (comment)).

Author: sarnex

clang/lib/Lex/PPMacroExpansion.cpp

@@ -1804,9 +1804,8 @@ void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
                                            diag::err_feature_check_malformed);
         if (!II)
           return false;
-        auto BuiltinID = II->getBuiltinID();
-        if (BuiltinID != 0) {
-          switch (BuiltinID) {
+        else if (II->getBuiltinID() != 0) {
+          switch (II->getBuiltinID()) {
           case Builtin::BI__builtin_cpu_is:
             return getTargetInfo().supportsCpuIs();
           case Builtin::BI__builtin_cpu_init:
@@ -1819,11 +1818,8 @@ void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
             // usual allocation and deallocation functions. Required by libc++
             return 201802;
           default:
-            // __has_builtin should return false for aux builtins.
-            if (getBuiltinInfo().isAuxBuiltinID(BuiltinID))
-              return false;
             return Builtin::evaluateRequiredTargetFeatures(
-                getBuiltinInfo().getRequiredFeatures(BuiltinID),
+                getBuiltinInfo().getRequiredFeatures(II->getBuiltinID()),
                 getTargetInfo().getTargetOpts().FeatureMap);
           }
           return true;

clang/test/Headers/__cpuidex_conflict.c

@@ -3,9 +3,7 @@
 // RUN: %clang_cc1 %s -ffreestanding -fms-extensions -fms-compatibility \
 // RUN:  -fms-compatibility-version=19.00 -triple x86_64-pc-windows-msvc -emit-llvm -o -
 // %clang_cc1 %s -ffreestanding -triple x86_64-w64-windows-gnu -fms-extensions -emit-llvm -o -
-//
-// FIXME: See https://github.com/llvm/llvm-project/pull/121839
-// RUN: not %clang_cc1 %s -ffreestanding -fopenmp -fopenmp-is-target-device -aux-triple x86_64-unknown-linux-gnu
+// RUN: %clang_cc1 %s -ffreestanding -fopenmp -fopenmp-is-target-device -aux-triple x86_64-unknown-linux-gnu
 
 typedef __SIZE_TYPE__ size_t;