[PATCH for-9.1 04/19] target/i386: do not use s->tmp0 and s->tmp4 to compute flags

[Paolo Bonzini]

Create a new temporary whenever flags have to use one, instead of using
s->tmp0 or s->tmp4.  NULL can now be passed as the scratch register
to gen_prepare_*.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/tcg/translate.c | 54 +++++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 23 deletions(-)

diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index 197cccb6c96..debc1b27283 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -947,9 +947,9 @@ static CCPrepare gen_prepare_eflags_c(DisasContext *s, TCGv 
reg)
     case CC_OP_SUBB ... CC_OP_SUBQ:
         /* (DATA_TYPE)CC_SRCT < (DATA_TYPE)CC_SRC */
         size = s->cc_op - CC_OP_SUBB;
-        t1 = gen_ext_tl(s->tmp0, cpu_cc_src, size, false);
-        /* If no temporary was used, be careful not to alias t1 and t0.  */
-        t0 = t1 == cpu_cc_src ? s->tmp0 : reg;
+        /* Be careful not to alias t1 and t0.  */
+        t1 = gen_ext_tl(NULL, cpu_cc_src, size, false);
+        t0 = (reg == t1 || !reg) ? tcg_temp_new() : reg;
         tcg_gen_mov_tl(t0, s->cc_srcT);
         gen_extu(size, t0);
         goto add_sub;
@@ -957,8 +957,9 @@ static CCPrepare gen_prepare_eflags_c(DisasContext *s, TCGv 
reg)
     case CC_OP_ADDB ... CC_OP_ADDQ:
         /* (DATA_TYPE)CC_DST < (DATA_TYPE)CC_SRC */
         size = s->cc_op - CC_OP_ADDB;
-        t1 = gen_ext_tl(s->tmp0, cpu_cc_src, size, false);
-        t0 = gen_ext_tl(reg, cpu_cc_dst, size, false);
+        /* Be careful not to alias t1 and t0.  */
+        t1 = gen_ext_tl(NULL, cpu_cc_src, size, false);
+        t0 = gen_ext_tl(reg == t1 ? NULL : reg, cpu_cc_dst, size, false);
     add_sub:
         return (CCPrepare) { .cond = TCG_COND_LTU, .reg = t0,
                              .reg2 = t1, .use_reg2 = true };
@@ -1002,6 +1003,9 @@ static CCPrepare gen_prepare_eflags_c(DisasContext *s, 
TCGv reg)
        /* The need to compute only C from CC_OP_DYNAMIC is important
           in efficiently implementing e.g. INC at the start of a TB.  */
        gen_update_cc_op(s);
+       if (!reg) {
+           reg = tcg_temp_new();
+       }
        gen_helper_cc_compute_c(reg, cpu_cc_dst, cpu_cc_src,
                                cpu_cc_src2, cpu_cc_op);
        return (CCPrepare) { .cond = TCG_COND_NE, .reg = reg,
@@ -1098,7 +1102,7 @@ static CCPrepare gen_prepare_cc(DisasContext *s, int b, 
TCGv reg)
     int inv, jcc_op, cond;
     MemOp size;
     CCPrepare cc;
-    TCGv t0;
+    TCGv t0, t1;
 
     inv = b & 1;
     jcc_op = (b >> 1) & 7;
@@ -1109,11 +1113,13 @@ static CCPrepare gen_prepare_cc(DisasContext *s, int b, 
TCGv reg)
         size = s->cc_op - CC_OP_SUBB;
         switch (jcc_op) {
         case JCC_BE:
-            tcg_gen_mov_tl(s->tmp4, s->cc_srcT);
-            gen_extu(size, s->tmp4);
-            t0 = gen_ext_tl(s->tmp0, cpu_cc_src, size, false);
-            cc = (CCPrepare) { .cond = TCG_COND_LEU, .reg = s->tmp4,
-                               .reg2 = t0, .use_reg2 = true };
+            /* Be careful not to alias t1 and t0.  */
+            t1 = gen_ext_tl(NULL, cpu_cc_src, size, false);
+            t0 = (reg == t1 || !reg) ? tcg_temp_new() : reg;
+            tcg_gen_mov_tl(t0, s->cc_srcT);
+            gen_extu(size, t0);
+            cc = (CCPrepare) { .cond = TCG_COND_LEU, .reg = t0,
+                               .reg2 = t1, .use_reg2 = true };
             break;
 
         case JCC_L:
@@ -1122,11 +1128,13 @@ static CCPrepare gen_prepare_cc(DisasContext *s, int b, 
TCGv reg)
         case JCC_LE:
             cond = TCG_COND_LE;
         fast_jcc_l:
-            tcg_gen_mov_tl(s->tmp4, s->cc_srcT);
-            gen_exts(size, s->tmp4);
-            t0 = gen_ext_tl(s->tmp0, cpu_cc_src, size, true);
-            cc = (CCPrepare) { .cond = cond, .reg = s->tmp4,
-                               .reg2 = t0, .use_reg2 = true };
+            /* Be careful not to alias t1 and t0.  */
+            t1 = gen_ext_tl(NULL, cpu_cc_src, size, true);
+            t0 = (reg == t1 || !reg) ? tcg_temp_new() : reg;
+            tcg_gen_mov_tl(t0, s->cc_srcT);
+            gen_exts(size, t0);
+            cc = (CCPrepare) { .cond = cond, .reg = t0,
+                               .reg2 = t1, .use_reg2 = true };
             break;
 
         default:
@@ -1160,8 +1168,8 @@ static CCPrepare gen_prepare_cc(DisasContext *s, int b, 
TCGv reg)
             break;
         case JCC_L:
             gen_compute_eflags(s);
-            if (reg == cpu_cc_src) {
-                reg = s->tmp0;
+            if (reg == cpu_cc_src || !reg) {
+                reg = tcg_temp_new();
             }
             tcg_gen_addi_tl(reg, cpu_cc_src, CC_O - CC_S);
             cc = (CCPrepare) { .cond = TCG_COND_TSTNE, .reg = reg,
@@ -1170,8 +1178,8 @@ static CCPrepare gen_prepare_cc(DisasContext *s, int b, 
TCGv reg)
         default:
         case JCC_LE:
             gen_compute_eflags(s);
-            if (reg == cpu_cc_src) {
-                reg = s->tmp0;
+            if (reg == cpu_cc_src || !reg) {
+                reg = tcg_temp_new();
             }
             tcg_gen_addi_tl(reg, cpu_cc_src, CC_O - CC_S);
             cc = (CCPrepare) { .cond = TCG_COND_TSTNE, .reg = reg,
@@ -1216,7 +1224,7 @@ static inline void gen_compute_eflags_c(DisasContext *s, 
TCGv reg)
    value 'b'. In the fast case, T0 is guaranteed not to be used. */
 static inline void gen_jcc1_noeob(DisasContext *s, int b, TCGLabel *l1)
 {
-    CCPrepare cc = gen_prepare_cc(s, b, s->T0);
+    CCPrepare cc = gen_prepare_cc(s, b, NULL);
 
     if (cc.use_reg2) {
         tcg_gen_brcond_tl(cc.cond, cc.reg, cc.reg2, l1);
@@ -1230,7 +1238,7 @@ static inline void gen_jcc1_noeob(DisasContext *s, int b, 
TCGLabel *l1)
    A translation block must end soon.  */
 static inline void gen_jcc1(DisasContext *s, int b, TCGLabel *l1)
 {
-    CCPrepare cc = gen_prepare_cc(s, b, s->T0);
+    CCPrepare cc = gen_prepare_cc(s, b, NULL);
 
     gen_update_cc_op(s);
     set_cc_op(s, CC_OP_DYNAMIC);
@@ -2495,7 +2503,7 @@ static void gen_jcc(DisasContext *s, int b, int diff)
 
 static void gen_cmovcc1(DisasContext *s, int b, TCGv dest, TCGv src)
 {
-    CCPrepare cc = gen_prepare_cc(s, b, s->T1);
+    CCPrepare cc = gen_prepare_cc(s, b, NULL);
 
     if (!cc.use_reg2) {
         cc.reg2 = tcg_constant_tl(cc.imm);
-- 
2.44.0