[PATCH] ppc: Use hard-float in ppc fp_hlper as early as possible. This would increase the performance better than enable hard-float it in soft-float.c; Just using fadd fsub fmul fdiv as a simple bench demo. With this patch, performance are increased 2x. and 1.3x than the one enable hard-float in soft-float.c Both version are not considerate inexact fp exception yet.

[luoyonggang@gmail.com]

From: Yonggang Luo <luoyonggang@gmail.com>

Just post as an idea to improve PPC fp performance.
With this idea, we have no need to adjust the helper orders.

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
---
 target/ppc/fpu_helper.c | 44 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/target/ppc/fpu_helper.c b/target/ppc/fpu_helper.c
index 2bd49a2cdf..79051e4540 100644
--- a/target/ppc/fpu_helper.c
+++ b/target/ppc/fpu_helper.c
@@ -926,6 +926,17 @@ static void float_invalid_op_addsub(CPUPPCState *env, bool set_fpcc,
 /* fadd - fadd. */
 float64 helper_fadd(CPUPPCState *env, float64 arg1, float64 arg2)
 {
+    CPU_DoubleU u1, u2;
+
+    u1.d = arg1;
+    u2.d = arg2;
+    CPU_DoubleU retDouble;
+    retDouble.nd = u1.nd + u2.nd;
+    if (likely(float64_is_zero_or_normal(retDouble.d)))
+    {
+        /* TODO: Handling inexact */
+        return retDouble.d;
+    }
     float64 ret = float64_add(arg1, arg2, &env->fp_status);
     int status = get_float_exception_flags(&env->fp_status);
 
@@ -941,6 +952,17 @@ float64 helper_fadd(CPUPPCState *env, float64 arg1, float64 arg2)
 /* fsub - fsub. */
 float64 helper_fsub(CPUPPCState *env, float64 arg1, float64 arg2)
 {
+    CPU_DoubleU u1, u2;
+
+    u1.d = arg1;
+    u2.d = arg2;
+    CPU_DoubleU retDouble;
+    retDouble.nd = u1.nd - u2.nd;
+    if (likely(float64_is_zero_or_normal(retDouble.d)))
+    {
+        /* TODO: Handling inexact */
+        return retDouble.d;
+    }
     float64 ret = float64_sub(arg1, arg2, &env->fp_status);
     int status = get_float_exception_flags(&env->fp_status);
 
@@ -967,6 +989,17 @@ static void float_invalid_op_mul(CPUPPCState *env, bool set_fprc,
 /* fmul - fmul. */
 float64 helper_fmul(CPUPPCState *env, float64 arg1, float64 arg2)
 {
+    CPU_DoubleU u1, u2;
+
+    u1.d = arg1;
+    u2.d = arg2;
+    CPU_DoubleU retDouble;
+    retDouble.nd = u1.nd * u2.nd;
+    if (likely(float64_is_zero_or_normal(retDouble.d)))
+    {
+        /* TODO: Handling inexact */
+        return retDouble.d;
+    }
     float64 ret = float64_mul(arg1, arg2, &env->fp_status);
     int status = get_float_exception_flags(&env->fp_status);
 
@@ -997,6 +1030,17 @@ static void float_invalid_op_div(CPUPPCState *env, bool set_fprc,
 /* fdiv - fdiv. */
 float64 helper_fdiv(CPUPPCState *env, float64 arg1, float64 arg2)
 {
+    CPU_DoubleU u1, u2;
+
+    u1.d = arg1;
+    u2.d = arg2;
+    CPU_DoubleU retDouble;
+    retDouble.nd = u1.nd / u2.nd;
+    if (likely(float64_is_zero_or_normal(retDouble.d)))
+    {
+        /* TODO: Handling inexact */
+        return retDouble.d;
+    }
     float64 ret = float64_div(arg1, arg2, &env->fp_status);
     int status = get_float_exception_flags(&env->fp_status);
 
-- 
2.23.0.windows.1