[Qemu-devel] [PATCH 9/9] target-alpha: Make use of fp_status.flush_inputs_to_zero.

[Richard Henderson]

This softfp feature post-dates the last major update to the Alpha
fpu translation.  We can make use of this to eliminate at least
one helper function that was performing this operation by hand.

Signed-off-by: Richard Henderson <address@hidden>
---
 target-alpha/cpu.h        |    1 -
 target-alpha/fpu_helper.c |   44 ++++++++++----------------------------------
 target-alpha/helper.c     |    8 +++-----
 target-alpha/helper.h     |    5 ++---
 target-alpha/translate.c  |   18 +++++++++++-------
 5 files changed, 26 insertions(+), 50 deletions(-)

diff --git a/target-alpha/cpu.h b/target-alpha/cpu.h
index c7787f6..6c5d28b 100644
--- a/target-alpha/cpu.h
+++ b/target-alpha/cpu.h
@@ -234,7 +234,6 @@ struct CPUAlphaState {
     uint8_t fpcr_exc_mask;
     uint8_t fpcr_dyn_round;
     uint8_t fpcr_flush_to_zero;
-    uint8_t fpcr_dnz;
     uint8_t fpcr_dnod;
     uint8_t fpcr_undz;
 
diff --git a/target-alpha/fpu_helper.c b/target-alpha/fpu_helper.c
index 39c411a..feb4e6f 100644
--- a/target-alpha/fpu_helper.c
+++ b/target-alpha/fpu_helper.c
@@ -88,21 +88,17 @@ void helper_fp_exc_raise_s(CPUAlphaState *env, uint32_t 
exc, uint32_t regno)
     }
 }
 
-/* Input remapping without software completion.  Handle denormal-map-to-zero
-   and trap for all other non-finite numbers.  */
-uint64_t helper_ieee_input(CPUAlphaState *env, uint64_t val)
+/* Input handing without software completion.  Trap for all
+   non-finite numbers.  */
+void helper_ieee_input(CPUAlphaState *env, uint64_t val)
 {
     uint32_t exp = (uint32_t)(val >> 52) & 0x7ff;
     uint64_t frac = val & 0xfffffffffffffull;
 
     if (exp == 0) {
-        if (frac != 0) {
-            /* If DNZ is set flush denormals to zero on input.  */
-            if (env->fpcr_dnz) {
-                val &= 1ull << 63;
-            } else {
-                arith_excp(env, GETPC(), EXC_M_UNF, 0);
-            }
+        /* Denormals without DNZ set raise an exception.  */
+        if (frac != 0 && !env->fp_status.flush_inputs_to_zero) {
+            arith_excp(env, GETPC(), EXC_M_UNF, 0);
         }
     } else if (exp == 0x7ff) {
         /* Infinity or NaN.  */
@@ -111,43 +107,23 @@ uint64_t helper_ieee_input(CPUAlphaState *env, uint64_t 
val)
            just emulates the insn to figure out what exception to use.  */
         arith_excp(env, GETPC(), frac ? EXC_M_INV : EXC_M_FOV, 0);
     }
-    return val;
 }
 
 /* Similar, but does not trap for infinities.  Used for comparisons.  */
-uint64_t helper_ieee_input_cmp(CPUAlphaState *env, uint64_t val)
+void helper_ieee_input_cmp(CPUAlphaState *env, uint64_t val)
 {
     uint32_t exp = (uint32_t)(val >> 52) & 0x7ff;
     uint64_t frac = val & 0xfffffffffffffull;
 
     if (exp == 0) {
-        if (frac != 0) {
-            /* If DNZ is set flush denormals to zero on input.  */
-            if (env->fpcr_dnz) {
-                val &= 1ull << 63;
-            } else {
-                arith_excp(env, GETPC(), EXC_M_UNF, 0);
-            }
+        /* Denormals without DNZ set raise an exception.  */
+        if (frac != 0 && !env->fp_status.flush_inputs_to_zero) {
+            arith_excp(env, GETPC(), EXC_M_UNF, 0);
         }
     } else if (exp == 0x7ff && frac) {
         /* NaN.  */
         arith_excp(env, GETPC(), EXC_M_INV, 0);
     }
-    return val;
-}
-
-/* Input remapping with software completion enabled.  All we have to do
-   is handle denormal-map-to-zero; all other inputs get exceptions as
-   needed from the actual operation.  */
-uint64_t helper_ieee_input_s(CPUAlphaState *env, uint64_t val)
-{
-    if (env->fpcr_dnz) {
-        uint32_t exp = (uint32_t)(val >> 52) & 0x7ff;
-        if (exp == 0) {
-            val &= 1ull << 63;
-        }
-    }
-    return val;
 }
 
 /* F floating (VAX) */
diff --git a/target-alpha/helper.c b/target-alpha/helper.c
index 3333bfa..765e650 100644
--- a/target-alpha/helper.c
+++ b/target-alpha/helper.c
@@ -82,7 +82,7 @@ uint64_t cpu_alpha_load_fpcr (CPUAlphaState *env)
         break;
     }
 
-    if (env->fpcr_dnz) {
+    if (env->fp_status.flush_inputs_to_zero) {
         r |= FPCR_DNZ;
     }
     if (env->fpcr_dnod) {
@@ -151,12 +151,10 @@ void cpu_alpha_store_fpcr (CPUAlphaState *env, uint64_t 
val)
     }
     env->fpcr_dyn_round = t;
 
-    env->fpcr_flush_to_zero
-      = (val & (FPCR_UNDZ|FPCR_UNFD)) == (FPCR_UNDZ|FPCR_UNFD);
-
-    env->fpcr_dnz = (val & FPCR_DNZ) != 0;
     env->fpcr_dnod = (val & FPCR_DNOD) != 0;
     env->fpcr_undz = (val & FPCR_UNDZ) != 0;
+    env->fpcr_flush_to_zero = env->fpcr_dnod & env->fpcr_undz;
+    env->fp_status.flush_inputs_to_zero = (val & FPCR_DNZ) != 0;
 }
 
 uint64_t helper_load_fpcr(CPUAlphaState *env)
diff --git a/target-alpha/helper.h b/target-alpha/helper.h
index 03cc185..9f97c5d 100644
--- a/target-alpha/helper.h
+++ b/target-alpha/helper.h
@@ -95,9 +95,8 @@ DEF_HELPER_FLAGS_1(fp_exc_get, TCG_CALL_CONST | 
TCG_CALL_PURE, i32, env)
 DEF_HELPER_3(fp_exc_raise, void, env, i32, i32)
 DEF_HELPER_3(fp_exc_raise_s, void, env, i32, i32)
 
-DEF_HELPER_2(ieee_input, i64, env, i64)
-DEF_HELPER_2(ieee_input_cmp, i64, env, i64)
-DEF_HELPER_2(ieee_input_s, i64, env, i64)
+DEF_HELPER_2(ieee_input, void, env, i64)
+DEF_HELPER_2(ieee_input_cmp, void, env, i64)
 
 #if !defined (CONFIG_USER_ONLY)
 DEF_HELPER_2(hw_ret, void, env, i64)
diff --git a/target-alpha/translate.c b/target-alpha/translate.c
index d09c939..e1d09be 100644
--- a/target-alpha/translate.c
+++ b/target-alpha/translate.c
@@ -661,15 +661,19 @@ static void gen_qual_flushzero(DisasContext *ctx, int 
fn11)
 
 static TCGv gen_ieee_input(int reg, int fn11, int is_cmp)
 {
-    TCGv val = tcg_temp_new();
+    TCGv val;
     if (reg == 31) {
-        tcg_gen_movi_i64(val, 0);
-    } else if (fn11 & QUAL_S) {
-        gen_helper_ieee_input_s(val, cpu_env, cpu_fir[reg]);
-    } else if (is_cmp) {
-        gen_helper_ieee_input_cmp(val, cpu_env, cpu_fir[reg]);
+        val = tcg_const_i64(0);
     } else {
-        gen_helper_ieee_input(val, cpu_env, cpu_fir[reg]);
+        if ((fn11 & QUAL_S) == 0) {
+            if (is_cmp) {
+                gen_helper_ieee_input_cmp(cpu_env, cpu_fir[reg]);
+            } else {
+                gen_helper_ieee_input(cpu_env, cpu_fir[reg]);
+            }
+        }
+        val = tcg_temp_new();
+        tcg_gen_mov_i64(val, cpu_fir[reg]);
     }
     return val;
 }
-- 
1.7.7.6