From 5db4b3f3ed9f769d5b02c1d1ccc52bfd71fb9afb Mon Sep 17 00:00:00 2001
From: Daniel Dunbar <daniel@zuster.org>
Date: Thu, 16 Oct 2008 03:51:50 +0000
Subject: [PATCH] Teach tryEvaluate that fabs, copysign, and unary +/- are
 constants for floats.  - With testcase, which also has some other things GCC
 folds but we    don't commented out in it.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@57624 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/AST/ExprConstant.cpp        | 37 +++++++++++++++++++++++-
 test/Sema/constant-builtins-2.c | 50 +++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+), 1 deletion(-)
 create mode 100644 test/Sema/constant-builtins-2.c

diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index cc2b4e6735..5bc4170e70 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -586,6 +586,7 @@ public:
   bool VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
   bool VisitCallExpr(const CallExpr *E);
 
+  bool VisitUnaryOperator(const UnaryOperator *E);
   bool VisitBinaryOperator(const BinaryOperator *E);
   bool VisitFloatingLiteral(const FloatingLiteral *E);
 };
@@ -625,14 +626,48 @@ bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
       }
     }
     return false;
+
+  case Builtin::BI__builtin_fabs:
+  case Builtin::BI__builtin_fabsf:
+  case Builtin::BI__builtin_fabsl:
+    if (!EvaluateFloat(E->getArg(0), Result, Info))
+      return false;
+    
+    if (Result.isNegative())
+      Result.changeSign();
+    return true;
+
+  case Builtin::BI__builtin_copysign: 
+  case Builtin::BI__builtin_copysignf: 
+  case Builtin::BI__builtin_copysignl: {
+    APFloat RHS(0.);
+    if (!EvaluateFloat(E->getArg(0), Result, Info) ||
+        !EvaluateFloat(E->getArg(1), RHS, Info))
+      return false;
+    Result.copySign(RHS);
+    return true;
+  }
   }
 }
 
+bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
+  if (!EvaluateFloat(E->getSubExpr(), Result, Info))
+    return false;
+
+  switch (E->getOpcode()) {
+  default: return false;
+  case UnaryOperator::Plus: 
+    return true;
+  case UnaryOperator::Minus:
+    Result.changeSign();
+    return true;
+  }
+}
 
 bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
   // FIXME: Diagnostics?  I really don't understand how the warnings
   // and errors are supposed to work.
-  APFloat LHS(0.0), RHS(0.0);
+  APFloat RHS(0.0);
   if (!EvaluateFloat(E->getLHS(), Result, Info))
     return false;
   if (!EvaluateFloat(E->getRHS(), RHS, Info))
diff --git a/test/Sema/constant-builtins-2.c b/test/Sema/constant-builtins-2.c
new file mode 100644
index 0000000000..d47cc3556b
--- /dev/null
+++ b/test/Sema/constant-builtins-2.c
@@ -0,0 +1,50 @@
+// RUN: clang -fsyntax-only %s
+
+// Math stuff
+
+double       g0  = __builtin_huge_val();
+float        g1  = __builtin_huge_valf();
+long double  g2  = __builtin_huge_vall();
+
+double       g3  = __builtin_inf();
+float        g4  = __builtin_inff();
+long double  g5  = __builtin_infl();
+
+double       g6  = __builtin_nan("");
+float        g7  = __builtin_nanf("");
+long double  g8  = __builtin_nanl("");
+
+// GCC constant folds these too (via native strtol):
+//double       g6_1  = __builtin_nan("1");
+//float        g7_1  = __builtin_nanf("1");
+//long double  g8_1  = __builtin_nanl("1");
+
+// APFloat doesn't have signalling NaN functions.
+//double       g9  = __builtin_nans("");
+//float        g10 = __builtin_nansf("");
+//long double  g11 = __builtin_nansl("");
+
+//int          g12 = __builtin_abs(-12);
+
+double       g13 = __builtin_fabs(-12.);
+double       g13_0 = __builtin_fabs(-0.);
+double       g13_1 = __builtin_fabs(-__builtin_inf());
+float        g14 = __builtin_fabsf(-12.f);
+// GCC doesn't eat this one.
+//long double  g15 = __builtin_fabsfl(-12.0L);
+
+float        g16 = __builtin_copysign(1.0, -1.0);
+double       g17 = __builtin_copysignf(1.0f, -1.0f);
+long double  g18 = __builtin_copysignl(1.0L, -1.0L);
+
+//double       g19 = __builtin_powi(2.0, 4);
+//float        g20 = __builtin_powif(2.0f, 4);
+//long double  g21 = __builtin_powil(2.0L, 4);
+
+// GCC misc stuff
+
+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);
-- 
2.40.0