target-ppc: optimize cmp translation

We know that only one bit (in addition to SO) is going to be set in
the condition register, so do two movconds instead of three setconds,
three shifts and two ORs.

For ppc64-linux-user, the code size reduction is around 5% and the
performance improvement slightly less than 10%.  For softmmu, the
improvement is around 5%.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index 396f422cf4077220a770768f673d463ef50dd3c1..bcd36d53537fece2366b7f69c1d03852ede7729e 100644 (file)
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -605,27 +605,22 @@ static opc_handler_t invalid_handler = {
 static inline void gen_op_cmp(TCGv arg0, TCGv arg1, int s, int crf)
 {
     TCGv t0 = tcg_temp_new();
-    TCGv_i32 t1 = tcg_temp_new_i32();
-
-    tcg_gen_trunc_tl_i32(cpu_crf[crf], cpu_so);
-
-    tcg_gen_setcond_tl((s ? TCG_COND_LT: TCG_COND_LTU), t0, arg0, arg1);
-    tcg_gen_trunc_tl_i32(t1, t0);
-    tcg_gen_shli_i32(t1, t1, CRF_LT_BIT);
-    tcg_gen_or_i32(cpu_crf[crf], cpu_crf[crf], t1);
+    TCGv t1 = tcg_temp_new();
+    TCGv_i32 t = tcg_temp_new_i32();
 
-    tcg_gen_setcond_tl((s ? TCG_COND_GT: TCG_COND_GTU), t0, arg0, arg1);
-    tcg_gen_trunc_tl_i32(t1, t0);
-    tcg_gen_shli_i32(t1, t1, CRF_GT_BIT);
-    tcg_gen_or_i32(cpu_crf[crf], cpu_crf[crf], t1);
+    tcg_gen_movi_tl(t0, CRF_EQ);
+    tcg_gen_movi_tl(t1, CRF_LT);
+    tcg_gen_movcond_tl((s ? TCG_COND_LT : TCG_COND_LTU), t0, arg0, arg1, t1, t0);
+    tcg_gen_movi_tl(t1, CRF_GT);
+    tcg_gen_movcond_tl((s ? TCG_COND_GT : TCG_COND_GTU), t0, arg0, arg1, t1, t0);
 
-    tcg_gen_setcond_tl(TCG_COND_EQ, t0, arg0, arg1);
-    tcg_gen_trunc_tl_i32(t1, t0);
-    tcg_gen_shli_i32(t1, t1, CRF_EQ_BIT);
-    tcg_gen_or_i32(cpu_crf[crf], cpu_crf[crf], t1);
+    tcg_gen_trunc_tl_i32(t, t0);
+    tcg_gen_trunc_tl_i32(cpu_crf[crf], cpu_so);
+    tcg_gen_or_i32(cpu_crf[crf], cpu_crf[crf], t);
 
     tcg_temp_free(t0);
-    tcg_temp_free_i32(t1);
+    tcg_temp_free(t1);
+    tcg_temp_free_i32(t);
 }
 
 static inline void gen_op_cmpi(TCGv arg0, target_ulong arg1, int s, int crf)