From: Craig Topper <craig.topper@intel.com>
Date: Wed, 8 Aug 2018 22:31:12 +0000 (+0000)
Subject: [Builtins] Add __builtin_clrsb support to IntExprEvaluator::VisitBuiltinCallExpr
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9c67812c6c9d5a4f9f82fbc93ceffd0130c8e080;p=clang

[Builtins] Add __builtin_clrsb support to IntExprEvaluator::VisitBuiltinCallExpr

This addresses a FIXME that has existed since before clang supported the builtin.

This time with only reviewed changes.

Differential Revision: https://reviews.llvm.org/D50471

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@339295 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 7e596d0715..0ce962e419 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -8117,9 +8117,15 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *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:
diff --git a/test/Sema/constant-builtins-2.c b/test/Sema/constant-builtins-2.c
index 40cfce1f4a..9bb5215b8d 100644
--- a/test/Sema/constant-builtins-2.c
+++ b/test/Sema/constant-builtins-2.c
@@ -176,6 +176,19 @@ 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