target-ppc: VXSQRT Should Not Be Set for NaNs

The Power ISA square root instructions (fsqrt[s], frsqrte[s]) must
set the FPSCR[VXSQRT] flag when operating on a negative value.
However, NaNs have no sign and therefore this flag should not
be set when operating on one.

Change the order of the checks in the helper code.  Move the
SNaN-to-QNaN macro to the top of the file so that it can be
re-used.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/target-ppc/fpu_helper.c b/target-ppc/fpu_helper.c
index 7f74466f32ecfca54d06fec7110388b2c40ed3b0..81db60f1dbab5ee376f4af5e8365b94256ba1eac 100644 (file)
--- a/target-ppc/fpu_helper.c
+++ b/target-ppc/fpu_helper.c
@@ -19,6 +19,9 @@
 #include "cpu.h"
 #include "exec/helper-proto.h"
 
+#define float64_snan_to_qnan(x) ((x) | 0x0008000000000000ULL)
+#define float32_snan_to_qnan(x) ((x) | 0x00400000)
+
 /*****************************************************************************/
 /* Floating point operations helpers */
 uint64_t helper_float32_to_float64(CPUPPCState *env, uint32_t arg)
@@ -920,14 +923,16 @@ uint64_t helper_fsqrt(CPUPPCState *env, uint64_t arg)
 
     farg.ll = arg;
 
-    if (unlikely(float64_is_neg(farg.d) && !float64_is_zero(farg.d))) {
-        /* Square root of a negative nonzero number */
-        farg.ll = fload_invalid_op_excp(env, POWERPC_EXCP_FP_VXSQRT, 1);
-    } else {
+    if (unlikely(float64_is_any_nan(farg.d))) {
         if (unlikely(float64_is_signaling_nan(farg.d))) {
-            /* sNaN square root */
+            /* sNaN reciprocal square root */
             fload_invalid_op_excp(env, POWERPC_EXCP_FP_VXSNAN, 1);
+            farg.ll = float64_snan_to_qnan(farg.ll);
         }
+    } else if (unlikely(float64_is_neg(farg.d) && !float64_is_zero(farg.d))) {
+        /* Square root of a negative nonzero number */
+        farg.ll = fload_invalid_op_excp(env, POWERPC_EXCP_FP_VXSQRT, 1);
+    } else {
         farg.d = float64_sqrt(farg.d, &env->fp_status);
     }
     return farg.ll;
@@ -974,17 +979,20 @@ uint64_t helper_frsqrte(CPUPPCState *env, uint64_t arg)
 
     farg.ll = arg;
 
-    if (unlikely(float64_is_neg(farg.d) && !float64_is_zero(farg.d))) {
-        /* Reciprocal square root of a negative nonzero number */
-        farg.ll = fload_invalid_op_excp(env, POWERPC_EXCP_FP_VXSQRT, 1);
-    } else {
+    if (unlikely(float64_is_any_nan(farg.d))) {
         if (unlikely(float64_is_signaling_nan(farg.d))) {
             /* sNaN reciprocal square root */
             fload_invalid_op_excp(env, POWERPC_EXCP_FP_VXSNAN, 1);
+            farg.ll = float64_snan_to_qnan(farg.ll);
         }
+    } else if (unlikely(float64_is_neg(farg.d) && !float64_is_zero(farg.d))) {
+        /* Reciprocal square root of a negative nonzero number */
+        farg.ll = fload_invalid_op_excp(env, POWERPC_EXCP_FP_VXSQRT, 1);
+    } else {
         farg.d = float64_sqrt(farg.d, &env->fp_status);
         farg.d = float64_div(float64_one, farg.d, &env->fp_status);
     }
+
     return farg.ll;
 }
 
@@ -2382,9 +2390,6 @@ void helper_##op(CPUPPCState *env, uint32_t opcode)                      \
 VSX_SCALAR_CMP(xscmpodp, 1)
 VSX_SCALAR_CMP(xscmpudp, 0)
 
-#define float64_snan_to_qnan(x) ((x) | 0x0008000000000000ULL)
-#define float32_snan_to_qnan(x) ((x) | 0x00400000)
-
 /* VSX_MAX_MIN - VSX floating point maximum/minimum
  *   name  - instruction mnemonic
  *   op    - operation (max or min)