[Builtins] Add __bulitin_clrsb support to IntExprEvaluator::VisitBuiltinCallExpr

[craig.topper]

Summary

Now that __builtin_clrsb is supported by clang, this patch adds constant evaluation of it to address the FIXME.

[erichkeane]

Looks easy enough, just note the test issue.

test/Sema/constant-builtins-2.c

191

Same name as line 190.

[craig.topper]

Fix duplicate variable name in the test. Not sure why that didn't complain

lib/AST/ExprConstant.cpp

if (!EvaluateInteger(E->getArg(0), Val, Info))
       return false;
 
     return Success(Val.byteSwap(), E);
   }
 
   case Builtin::BI__builtin_classify_type:
     return Success((int)EvaluateBuiltinClassifyType(E, Info.getLangOpts()), E);
 
-  // FIXME: BI__builtin_clrsb
-  // FIXME: BI__builtin_clrsbl
-  // FIXME: BI__builtin_clrsbll
+  case Builtin::BI__builtin_clrsb:
+  case Builtin::BI__builtin_clrsbl:
+  case Builtin::BI__builtin_clrsbll: {
+    APSInt Val;
+    if (!EvaluateInteger(E->getArg(0), Val, Info))
+      return false;
+
+    return Success(Val.getBitWidth() - Val.getMinSignedBits(), E);
+  }
 
   case Builtin::BI__builtin_clz:
   case Builtin::BI__builtin_clzl:
   case Builtin::BI__builtin_clzll:
   case Builtin::BI__builtin_clzs: {
     APSInt Val;
     if (!EvaluateInteger(E->getArg(0), Val, Info))
       return false;

test/Sema/constant-builtins-2.c

 
 char ffs1[__builtin_ffs(0) == 0 ? 1 : -1];
 char ffs2[__builtin_ffs(1) == 1 ? 1 : -1];
 char ffs3[__builtin_ffs(0xfbe71) == 1 ? 1 : -1];
 char ffs4[__builtin_ffs(0xfbe70) == 5 ? 1 : -1];
 char ffs5[__builtin_ffs(1U << (BITSIZE(int) - 1)) == BITSIZE(int) ? 1 : -1];
 char ffs6[__builtin_ffsl(0x10L) == 5 ? 1 : -1];
 char ffs7[__builtin_ffsll(0x100LL) == 9 ? 1 : -1];
+
+char clrsb1[__builtin_clrsb(0) == BITSIZE(int) - 1 ? 1 : -1];
+char clrsb2[__builtin_clrsbl(0L) == BITSIZE(long) - 1 ? 1 : -1];
+char clrsb3[__builtin_clrsbll(0LL) == BITSIZE(long long) - 1 ? 1 : -1];
+char clrsb4[__builtin_clrsb(~0) == BITSIZE(int) - 1 ? 1 : -1];
+char clrsb5[__builtin_clrsbl(~0L) == BITSIZE(long) - 1 ? 1 : -1];
+char clrsb6[__builtin_clrsbll(~0LL) == BITSIZE(long long) - 1 ? 1 : -1];
+char clrsb7[__builtin_clrsb(1) == BITSIZE(int) - 2 ? 1 : -1];
+char clrsb8[__builtin_clrsb(~1) == BITSIZE(int) - 2 ? 1 : -1];
+char clrsb9[__builtin_clrsb(1 << (BITSIZE(int) - 1)) == 0 ? 1 : -1];
+char clrsb10[__builtin_clrsb(~(1 << (BITSIZE(int) - 1))) == 0 ? 1 : -1];
+char clrsb11[__builtin_clrsb(0xf) == BITSIZE(int) - 5 ? 1 : -1];
+char clrsb12[__builtin_clrsb(~0x1f) == BITSIZE(int) - 6 ? 1 : -1];
 #undef BITSIZE
 
 // GCC misc stuff
 
 extern int f();
 
 int h0 = __builtin_types_compatible_p(int, float);
 //int h1 = __builtin_choose_expr(1, 10, f());