[Qemu-devel] [PATCH 12/20] target-sparc: Remove gen_opc_jump_pc

[Richard Henderson <rth@twiddle.net>]

Since jump_pc[1] is always npc + 4, and since we
only continue translation when pc + 4 == npc, we
can infer that jump_pc[1] == pc + 8.

Because of that, we can encode the branch destination
into a single word, and store that in npc.

Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 target-sparc/translate.c | 50 +++++++++++++++++++++++-------------------------
 1 file changed, 24 insertions(+), 26 deletions(-)

diff --git a/target-sparc/translate.c b/target-sparc/translate.c
index 8aa19e1..b1e533f 100644
--- a/target-sparc/translate.c
+++ b/target-sparc/translate.c
@@ -39,7 +39,7 @@
 
 #define DYNAMIC_PC  1 /* dynamic pc value */
 #define JUMP_PC     2 /* dynamic pc value which takes only two values
-                         according to jump_pc[T2] */
+                         according to npc & ~3 and pc + 4.  */
 
 /* global register indexes */
 static TCGv_ptr cpu_env, cpu_regwptr;
@@ -65,14 +65,12 @@ static TCGv cpu_wim;
 static TCGv_i64 cpu_fpr[TARGET_DPREGS];
 
 static target_ulong gen_opc_npc[OPC_BUF_SIZE];
-static target_ulong gen_opc_jump_pc[2];
 
 #include "exec/gen-icount.h"
 
 typedef struct DisasContext {
     target_ulong pc;    /* current Program Counter: integer or DYNAMIC_PC */
     target_ulong npc;   /* next PC: integer or DYNAMIC_PC or JUMP_PC */
-    target_ulong jump_pc[2]; /* used when JUMP_PC pc value is used */
     int is_br;
     int mem_idx;
     int fpu_enabled;
@@ -976,9 +974,7 @@ static void gen_branch_n(DisasContext *dc, target_ulong pc1)
 
     if (likely(npc != DYNAMIC_PC)) {
         dc->pc = npc;
-        dc->jump_pc[0] = pc1;
-        dc->jump_pc[1] = npc + 4;
-        dc->npc = JUMP_PC;
+        dc->npc = pc1 | JUMP_PC;
     } else {
         TCGv t, z;
 
@@ -997,12 +993,15 @@ static void gen_branch_n(DisasContext *dc, target_ulong pc1)
 
 static inline void gen_generic_branch(DisasContext *dc)
 {
-    TCGv npc0 = tcg_const_tl(dc->jump_pc[0]);
-    TCGv npc1 = tcg_const_tl(dc->jump_pc[1]);
-    TCGv zero = tcg_const_tl(0);
+    TCGv npc0, npc1, zero;
 
-    tcg_gen_movcond_tl(TCG_COND_NE, cpu_npc, cpu_cond, zero, npc0, npc1);
+    assert((dc->npc & 3) == JUMP_PC);
+    assert((dc->pc & 3) == 0);
 
+    npc0 = tcg_const_tl(dc->npc & ~3);
+    npc1 = tcg_const_tl(dc->pc + 4);
+    zero = tcg_const_tl(0);
+    tcg_gen_movcond_tl(TCG_COND_NE, cpu_npc, cpu_cond, zero, npc0, npc1);
     tcg_temp_free(npc0);
     tcg_temp_free(npc1);
     tcg_temp_free(zero);
@@ -1012,7 +1011,7 @@ static inline void gen_generic_branch(DisasContext *dc)
    have been set for a jump */
 static inline void flush_cond(DisasContext *dc)
 {
-    if (dc->npc == JUMP_PC) {
+    if (dc->npc & JUMP_PC) {
         gen_generic_branch(dc);
         dc->npc = DYNAMIC_PC;
     }
@@ -1020,7 +1019,7 @@ static inline void flush_cond(DisasContext *dc)
 
 static inline void save_npc(DisasContext *dc)
 {
-    if (dc->npc == JUMP_PC) {
+    if (dc->npc & JUMP_PC) {
         gen_generic_branch(dc);
         dc->npc = DYNAMIC_PC;
     } else if (dc->npc != DYNAMIC_PC) {
@@ -1044,7 +1043,7 @@ static inline void save_state(DisasContext *dc)
 
 static inline void gen_mov_pc_npc(DisasContext *dc)
 {
-    if (dc->npc == JUMP_PC) {
+    if (dc->npc & JUMP_PC) {
         gen_generic_branch(dc);
         tcg_gen_mov_tl(cpu_pc, cpu_npc);
         dc->pc = DYNAMIC_PC;
@@ -5122,9 +5121,9 @@ static void disas_sparc_insn(DisasContext * dc, unsigned int insn)
     if (dc->npc == DYNAMIC_PC) {
         dc->pc = DYNAMIC_PC;
         gen_op_next_insn();
-    } else if (dc->npc == JUMP_PC) {
-        /* we can do a static jump */
-        gen_branch2(dc, dc->jump_pc[0], dc->jump_pc[1], cpu_cond);
+    } else if (dc->npc & JUMP_PC) {
+        assert((dc->pc & 3) == 0);
+        gen_branch2(dc, dc->npc & ~3, dc->pc + 4, cpu_cond);
         dc->is_br = 1;
     } else {
         dc->pc = dc->npc;
@@ -5324,8 +5323,6 @@ static inline void gen_intermediate_code_internal(SPARCCPU *cpu,
 #if 0
         log_page_dump();
 #endif
-        gen_opc_jump_pc[0] = dc->jump_pc[0];
-        gen_opc_jump_pc[1] = dc->jump_pc[1];
     } else {
         tb->size = last_pc + 4 - pc_start;
         tb->icount = num_insns;
@@ -5453,17 +5450,18 @@ void gen_intermediate_code_init(CPUSPARCState *env)
 
 void restore_state_to_opc(CPUSPARCState *env, TranslationBlock *tb, int pc_pos)
 {
-    target_ulong npc;
-    env->pc = tcg_ctx.gen_opc_pc[pc_pos];
+    target_ulong pc, npc;
+
+    env->pc = pc = tcg_ctx.gen_opc_pc[pc_pos];
     npc = gen_opc_npc[pc_pos];
-    if (npc == 1) {
-        /* dynamic NPC: already stored */
-    } else if (npc == 2) {
-        /* jump PC: use 'cond' and the jump targets of the translation */
+    if (npc == DYNAMIC_PC) {
+        /* already stored */
+    } else if (npc & JUMP_PC) {
+        /* use 'cond' and the jump targets of the translation */
         if (env->cond) {
-            env->npc = gen_opc_jump_pc[0];
+            env->npc = npc & ~3;
         } else {
-            env->npc = gen_opc_jump_pc[1];
+            env->npc = pc + 8;
         }
     } else {
         env->npc = npc;
-- 
2.4.3