Merge pull request #204 from jprotopopov-ut/builtin-choose-expr-1

Try to evaluate `__builtin_choose_expr` arguments as constants if possible

Author: sim642

src/frontc/cabs2cil.ml

@@ -4459,7 +4459,7 @@ and doExp (asconst: bool)   (* This expression is used as a constant *)
                   the castTo do this work. This was necessary for
                   test/small1/union5, in which a transparent union is passed
                   as an argument *)
-              let (sa, a', att) = force_right_to_left_evaluation (doExp false a (AExp None)) in
+              let (sa, a', att) = force_right_to_left_evaluation (doExp asconst a (AExp None)) in
               let (_, a'') = castTo ~kind:Implicit att at a' in (* C11 6.5.2.2.7 *)
               (sa :: ss, a'' :: args')
             | ([], args) -> (* No more types *)
@@ -4469,7 +4469,7 @@ and doExp (asconst: bool)   (* This expression is used as a constant *)
                 | [] -> ([], [])
                 | a :: args ->
                     let (ss, args') = loop args in
-                    let (sa, a', at) = force_right_to_left_evaluation (doExp false a (AExp None)) in
+                    let (sa, a', at) = force_right_to_left_evaluation (doExp asconst a (AExp None)) in
                     if isBuiltinChooseExprOrTgmath then
                       (* This built-in function is analogous to the `? :'
                           operator in C, except that the expression returned

test/small1/builtin_choose_expr2.c

@@ -0,0 +1,5 @@
+// Both bitfield widths shall be evaluated constantly
+struct S1 {
+    int x : __builtin_choose_expr(sizeof(long) > sizeof(int) || sizeof(int) > sizeof(short), 1, 2),
+        y : __builtin_choose_expr(sizeof(char) > sizeof(short) && sizeof(char) == sizeof(char), 3, 4);
+} s1;

test/testcil.pl

@@ -552,6 +552,7 @@ sub addToGroup {
 addTest("test/builtin2 ");
 addTest("testrun/builtin3 ");
 addTest("testrun/builtin_choose_expr");
+addTest("test/builtin_choose_expr2");
 addTest("testrungcc/builtin_object_size _GNUCC=1 OPTIMIZE=1");
 addTest("testrun/builtin4 ");
 addTest("test/builtin5 ");