Allow __builtin_bswap32/64 in constant expressions, like gcc does. Patch by Tijl Coosemans!

llvm-svn: 164841

3 files changed, 13 insertions, 0 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 8f3f84d07d7..c4fd70a8c8b 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -4296,6 +4296,15 @@ bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) {
     return Error(E);
   }
 
+  case Builtin::BI__builtin_bswap32:
+  case Builtin::BI__builtin_bswap64: {
+    APSInt Val;
+    if (!EvaluateInteger(E->getArg(0), Val, Info))
+      return false;
+
+    return Success(Val.byteSwap(), E);
+  }
+
   case Builtin::BI__builtin_classify_type:
     return Success(EvaluateBuiltinClassifyType(E), E);
 
diff --git a/clang/test/Sema/constant-builtins-2.c b/clang/test/Sema/constant-builtins-2.c
index 68b46bf19ad..d78a176ef49 100644
--- a/clang/test/Sema/constant-builtins-2.c
+++ b/clang/test/Sema/constant-builtins-2.c
@@ -48,6 +48,8 @@ extern int f();
 int h0 = __builtin_types_compatible_p(int, float);
 //int h1 = __builtin_choose_expr(1, 10, f());
 //int h2 = __builtin_expect(0, 0);
+int h3 = __builtin_bswap32(0x1234) == 0x34120000 ? 1 : f();
+int h4 = __builtin_bswap64(0x1234) == 0x3412000000000000 ? 1 : f();
 extern long int bi0;
 extern __typeof__(__builtin_expect(0, 0)) bi0;
 
diff --git a/clang/test/Sema/constant-builtins.c b/clang/test/Sema/constant-builtins.c
index 5d67fc7cb71..1562623c0af 100644
--- a/clang/test/Sema/constant-builtins.c
+++ b/clang/test/Sema/constant-builtins.c
@@ -16,6 +16,8 @@ extern int f();
 int h0 = __builtin_types_compatible_p(int,float);
 //int h1 = __builtin_choose_expr(1, 10, f());
 //int h2 = __builtin_expect(0, 0);
+int h3 = __builtin_bswap32(0x1234) == 0x34120000 ? 1 : f();
+int h4 = __builtin_bswap64(0x1234) == 0x3412000000000000 ? 1 : f();
 
 short somefunc();