[clang] Implement __builtin_{clzg,ctzg} (#83431)

Fixes #83075, fixes #83076.

1 files changed, 47 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index ef3ab16..246e357 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -2399,6 +2399,48 @@ static bool SemaBuiltinPopcountg(Sema &S, CallExpr *TheCall) {
   return false;
 }
 
+/// Checks that __builtin_{clzg,ctzg} was called with a first argument, which is
+/// an unsigned integer, and an optional second argument, which is promoted to
+/// an 'int'.
+static bool SemaBuiltinCountZeroBitsGeneric(Sema &S, CallExpr *TheCall) {
+  if (checkArgCountRange(S, TheCall, 1, 2))
+    return true;
+
+  ExprResult Arg0Res = S.DefaultLvalueConversion(TheCall->getArg(0));
+  if (Arg0Res.isInvalid())
+    return true;
+
+  Expr *Arg0 = Arg0Res.get();
+  TheCall->setArg(0, Arg0);
+
+  QualType Arg0Ty = Arg0->getType();
+
+  if (!Arg0Ty->isUnsignedIntegerType()) {
+    S.Diag(Arg0->getBeginLoc(), diag::err_builtin_invalid_arg_type)
+        << 1 << /*unsigned integer ty*/ 7 << Arg0Ty;
+    return true;
+  }
+
+  if (TheCall->getNumArgs() > 1) {
+    ExprResult Arg1Res = S.UsualUnaryConversions(TheCall->getArg(1));
+    if (Arg1Res.isInvalid())
+      return true;
+
+    Expr *Arg1 = Arg1Res.get();
+    TheCall->setArg(1, Arg1);
+
+    QualType Arg1Ty = Arg1->getType();
+
+    if (!Arg1Ty->isSpecificBuiltinType(BuiltinType::Int)) {
+      S.Diag(Arg1->getBeginLoc(), diag::err_builtin_invalid_arg_type)
+          << 2 << /*'int' ty*/ 8 << Arg1Ty;
+      return true;
+    }
+  }
+
+  return false;
+}
+
 ExprResult
 Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
                                CallExpr *TheCall) {
@@ -3187,6 +3229,11 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
     if (SemaBuiltinPopcountg(*this, TheCall))
       return ExprError();
     break;
+  case Builtin::BI__builtin_clzg:
+  case Builtin::BI__builtin_ctzg:
+    if (SemaBuiltinCountZeroBitsGeneric(*this, TheCall))
+      return ExprError();
+    break;
   }
 
   if (getLangOpts().HLSL && CheckHLSLBuiltinFunctionCall(BuiltinID, TheCall))