feat: Use APInt built-in methods

Author: ahmednoursphinx

clang/lib/AST/ByteCode/InterpBuiltin.cpp

@@ -4584,19 +4584,10 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
   case X86::BI__builtin_ia32_kunpcksi:
     return interp__builtin_elementwise_int_binop(
         S, OpPC, Call, [](const APSInt &A, const APSInt &B) {
-          // Generic kunpack: extract
-          // lower half of each operand
-          // and concatenate Result =
-          // (A[HalfWidth-1:0] <<
-          // HalfWidth) |
-          // B[HalfWidth-1:0]
-          unsigned HalfWidth = A.getBitWidth() / 2;
-          APSInt Result(A.getLoBits(HalfWidth).zext(A.getBitWidth()),
-                        A.isUnsigned());
-          Result <<= HalfWidth;
-          Result |= APSInt(B.getLoBits(HalfWidth).zext(B.getBitWidth()),
-                           B.isUnsigned());
-          return Result;
+          // Generic kunpack: extract lower half of each operand and concatenate
+          // Result = A[HalfWidth-1:0] concat B[HalfWidth-1:0]
+          unsigned BW = A.getBitWidth();
+          return APSInt(A.trunc(BW / 2).concat(B.trunc(BW / 2)), A.isUnsigned());
         });
 
   case X86::BI__builtin_ia32_phminposuw128:

clang/lib/AST/ExprConstant.cpp

@@ -16296,12 +16296,9 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
       return false;
 
     // Generic kunpack: extract lower half of each operand and concatenate
-    // Result = (A[HalfWidth-1:0] << HalfWidth) | B[HalfWidth-1:0]
-    unsigned HalfWidth = A.getBitWidth() / 2;
-    APSInt Result(A.getLoBits(HalfWidth).zext(A.getBitWidth()), A.isUnsigned());
-    Result <<= HalfWidth;
-    Result |=
-        APSInt(B.getLoBits(HalfWidth).zext(B.getBitWidth()), B.isUnsigned());
+    // Result = A[HalfWidth-1:0] concat B[HalfWidth-1:0]
+    unsigned BW = A.getBitWidth();
+    APSInt Result(A.trunc(BW / 2).concat(B.trunc(BW / 2)), A.isUnsigned());
     return Success(Result, E);
   }