re PR tree-optimization/57066 (std::logb(-inf) returns wrong value)

	PR tree-optimization/57066
        * builtins.c (fold_builtin_logb): Return +Inf for -Inf.

        * gcc.dg/torture/builtin-logb-1.c: Adjust testcase.

From-SVN: r198308

4 files changed, 36 insertions, 17 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ad47f59..41a11e3 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2013-04-25  Marek Polacek  <polacek@redhat.com>
+
+	PR tree-optimization/57066
+        * builtins.c (fold_builtin_logb): Return +Inf for -Inf.
+
 2013-04-25  James Greenhalgh  <jame.greenhalgh@arm.com>
 
 	* config/aarch64/aarch64-simd.md (neg<mode>2): Use VDQ iterator.
diff --git a/gcc/builtins.c b/gcc/builtins.c
index efab82e..1fbd2f3 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -9698,7 +9698,16 @@ fold_builtin_logb (location_t loc, tree arg, tree rettype)
       case rvc_inf:
 	/* If arg is Inf or NaN and we're logb, return it.  */
 	if (TREE_CODE (rettype) == REAL_TYPE)
-	  return fold_convert_loc (loc, rettype, arg);
+	  {
+	    /* For logb(-Inf) we have to return +Inf.  */
+	    if (real_isinf (value) && real_isneg (value))
+	      {
+		REAL_VALUE_TYPE tem;
+		real_inf (&tem);
+		return build_real (rettype, tem);
+	      }
+	    return fold_convert_loc (loc, rettype, arg);
+	  }
 	/* Fall through... */
       case rvc_zero:
 	/* Zero may set errno and/or raise an exception for logb, also
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 32d986a..bcfc726 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2013-04-25  Marek Polacek  <polacek@redhat.com>
+
+	PR tree-optimization/57066
+        * gcc.dg/torture/builtin-logb-1.c: Adjust testcase.
+
 2013-04-25  James Greenhalgh  <james.greenhalgh@arm.com>
 	    Tejas Belagod  <tejas.belagod@arm.com>
 
diff --git a/gcc/testsuite/gcc.dg/torture/builtin-logb-1.c b/gcc/testsuite/gcc.dg/torture/builtin-logb-1.c
index 387ed2f..d759d1c 100644
--- a/gcc/testsuite/gcc.dg/torture/builtin-logb-1.c
+++ b/gcc/testsuite/gcc.dg/torture/builtin-logb-1.c
@@ -48,25 +48,25 @@ extern void link_error(int);
 /* Test if FUNCRES(FUNC(NEG FUNCARG(ARGARG))) is false.  Check the
    sign as well.  */
 #ifndef __SPU__
-#define TESTIT3(FUNC,NEG,FUNCARG,ARGARG,FUNCRES) do { \
+#define TESTIT3(FUNC,NEG,FUNCARG,ARGARG,FUNCRES,NEG2) do { \
   if (!__builtin_##FUNCRES##f(__builtin_##FUNC(NEG __builtin_##FUNCARG##f(ARGARG))) \
-      || CKSGN_F(__builtin_##FUNC##f(NEG __builtin_##FUNCARG##f(ARGARG)), NEG __builtin_##FUNCARG##f(ARGARG))) \
+      || CKSGN_F(__builtin_##FUNC##f(NEG __builtin_##FUNCARG##f(ARGARG)), NEG2 __builtin_##FUNCARG##f(ARGARG))) \
     link_error(__LINE__); \
   if (!__builtin_##FUNCRES(__builtin_##FUNC(NEG __builtin_##FUNCARG(ARGARG))) \
-      || CKSGN(__builtin_##FUNC(NEG __builtin_##FUNCARG(ARGARG)), NEG __builtin_##FUNCARG(ARGARG))) \
+      || CKSGN(__builtin_##FUNC(NEG __builtin_##FUNCARG(ARGARG)), NEG2 __builtin_##FUNCARG(ARGARG))) \
     link_error(__LINE__); \
   if (!__builtin_##FUNCRES##l(__builtin_##FUNC##l(NEG __builtin_##FUNCARG##l(ARGARG))) \
-      || CKSGN_L(__builtin_##FUNC##l(NEG __builtin_##FUNCARG##l(ARGARG)), NEG __builtin_##FUNCARG##l(ARGARG))) \
+      || CKSGN_L(__builtin_##FUNC##l(NEG __builtin_##FUNCARG##l(ARGARG)), NEG2 __builtin_##FUNCARG##l(ARGARG))) \
     link_error(__LINE__); \
   } while (0)
 #else
-#define TESTIT3(FUNC,NEG,FUNCARG,ARGARG,FUNCRES) do { \
+#define TESTIT3(FUNC,NEG,FUNCARG,ARGARG,FUNCRES,NEG2) do { \
   /* SPU single-precision floating point format does not support Inf or Nan.  */ \
   if (!__builtin_##FUNCRES(__builtin_##FUNC(NEG __builtin_##FUNCARG(ARGARG))) \
-      || CKSGN(__builtin_##FUNC(NEG __builtin_##FUNCARG(ARGARG)), NEG __builtin_##FUNCARG(ARGARG))) \
+      || CKSGN(__builtin_##FUNC(NEG __builtin_##FUNCARG(ARGARG)), NEG2 __builtin_##FUNCARG(ARGARG))) \
     link_error(__LINE__); \
   if (!__builtin_##FUNCRES##l(__builtin_##FUNC##l(NEG __builtin_##FUNCARG##l(ARGARG))) \
-      || CKSGN_L(__builtin_##FUNC##l(NEG __builtin_##FUNCARG##l(ARGARG)), NEG __builtin_##FUNCARG##l(ARGARG))) \
+      || CKSGN_L(__builtin_##FUNC##l(NEG __builtin_##FUNCARG##l(ARGARG)), NEG2 __builtin_##FUNCARG##l(ARGARG))) \
     link_error(__LINE__); \
   } while (0)
 #endif
@@ -173,15 +173,15 @@ foo(void)
 
   /* Test for f(+-Inf) -> +-Inf and f(+-NaN) -> +-NaN, regardless of
      the radix.  */
-  TESTIT3 (logb, ,inf, , isinf);
-  TESTIT3 (logb, - ,inf, , isinf);
-  TESTIT3 (logb,  ,nan, "", isnan);
-  TESTIT3 (logb, - ,nan, "", isnan);
-
-  TESTIT3 (significand, ,inf, , isinf);
-  TESTIT3 (significand, - ,inf, , isinf);
-  TESTIT3 (significand,  ,nan, "", isnan);
-  TESTIT3 (significand, - ,nan, "", isnan);
+  TESTIT3 (logb, ,inf, , isinf, );
+  TESTIT3 (logb, - ,inf, , isinf, );
+  TESTIT3 (logb,  ,nan, "", isnan, );
+  TESTIT3 (logb, - ,nan, "", isnan, -);
+
+  TESTIT3 (significand, ,inf, , isinf, );
+  TESTIT3 (significand, - ,inf, , isinf, -);
+  TESTIT3 (significand,  ,nan, "", isnan, );
+  TESTIT3 (significand, - ,nan, "", isnan, -);
 }
 
 int main()