From bb0356170a60ce31d992ad273bdede2075724a29 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Thu, 20 Oct 2022 13:06:38 +1000 Subject: [PATCH] target/arm: Change gen_jmp* to work on displacements In preparation for TARGET_TB_PCREL, reduce reliance on absolute values. Reviewed-by: Peter Maydell Signed-off-by: Richard Henderson Message-id: 20221020030641.2066807-7-richard.henderson@linaro.org Signed-off-by: Peter Maydell --- target/arm/translate.c | 37 +++++++++++++++++++++---------------- 1 file changed, 21 insertions(+), 16 deletions(-) diff --git a/target/arm/translate.c b/target/arm/translate.c index 9104ab8232..ca128edab7 100644 --- a/target/arm/translate.c +++ b/target/arm/translate.c @@ -266,6 +266,12 @@ static uint32_t read_pc(DisasContext *s) return s->pc_curr + (s->thumb ? 4 : 8); } +/* The pc_curr difference for an architectural jump. */ +static target_long jmp_diff(DisasContext *s, target_long diff) +{ + return diff + (s->thumb ? 4 : 8); +} + /* Set a variable to the value of a CPU register. */ void load_reg_var(DisasContext *s, TCGv_i32 var, int reg) { @@ -2592,7 +2598,7 @@ static void gen_goto_ptr(void) * cpu_loop_exec. Any live exit_requests will be processed as we * enter the next TB. */ -static void gen_goto_tb(DisasContext *s, int n, int diff) +static void gen_goto_tb(DisasContext *s, int n, target_long diff) { target_ulong dest = s->pc_curr + diff; @@ -2608,10 +2614,8 @@ static void gen_goto_tb(DisasContext *s, int n, int diff) } /* Jump, specifying which TB number to use if we gen_goto_tb() */ -static inline void gen_jmp_tb(DisasContext *s, uint32_t dest, int tbno) +static void gen_jmp_tb(DisasContext *s, target_long diff, int tbno) { - int diff = dest - s->pc_curr; - if (unlikely(s->ss_active)) { /* An indirect jump so that we still trigger the debug exception. */ gen_update_pc(s, diff); @@ -2653,9 +2657,9 @@ static inline void gen_jmp_tb(DisasContext *s, uint32_t dest, int tbno) } } -static inline void gen_jmp(DisasContext *s, uint32_t dest) +static inline void gen_jmp(DisasContext *s, target_long diff) { - gen_jmp_tb(s, dest, 0); + gen_jmp_tb(s, diff, 0); } static inline void gen_mulxy(TCGv_i32 t0, TCGv_i32 t1, int x, int y) @@ -8322,7 +8326,7 @@ static bool trans_CLRM(DisasContext *s, arg_CLRM *a) static bool trans_B(DisasContext *s, arg_i *a) { - gen_jmp(s, read_pc(s) + a->imm); + gen_jmp(s, jmp_diff(s, a->imm)); return true; } @@ -8337,14 +8341,14 @@ static bool trans_B_cond_thumb(DisasContext *s, arg_ci *a) return true; } arm_skip_unless(s, a->cond); - gen_jmp(s, read_pc(s) + a->imm); + gen_jmp(s, jmp_diff(s, a->imm)); return true; } static bool trans_BL(DisasContext *s, arg_i *a) { tcg_gen_movi_i32(cpu_R[14], s->base.pc_next | s->thumb); - gen_jmp(s, read_pc(s) + a->imm); + gen_jmp(s, jmp_diff(s, a->imm)); return true; } @@ -8364,7 +8368,8 @@ static bool trans_BLX_i(DisasContext *s, arg_BLX_i *a) } tcg_gen_movi_i32(cpu_R[14], s->base.pc_next | s->thumb); store_cpu_field_constant(!s->thumb, thumb); - gen_jmp(s, (read_pc(s) & ~3) + a->imm); + /* This jump is computed from an aligned PC: subtract off the low bits. */ + gen_jmp(s, jmp_diff(s, a->imm - (s->pc_curr & 3))); return true; } @@ -8525,10 +8530,10 @@ static bool trans_WLS(DisasContext *s, arg_WLS *a) * when we take this upcoming exit from this TB, so gen_jmp_tb() is OK. */ } - gen_jmp_tb(s, s->base.pc_next, 1); + gen_jmp_tb(s, curr_insn_len(s), 1); gen_set_label(nextlabel); - gen_jmp(s, read_pc(s) + a->imm); + gen_jmp(s, jmp_diff(s, a->imm)); return true; } @@ -8608,7 +8613,7 @@ static bool trans_LE(DisasContext *s, arg_LE *a) if (a->f) { /* Loop-forever: just jump back to the loop start */ - gen_jmp(s, read_pc(s) - a->imm); + gen_jmp(s, jmp_diff(s, -a->imm)); return true; } @@ -8639,7 +8644,7 @@ static bool trans_LE(DisasContext *s, arg_LE *a) tcg_temp_free_i32(decr); } /* Jump back to the loop start */ - gen_jmp(s, read_pc(s) - a->imm); + gen_jmp(s, jmp_diff(s, -a->imm)); gen_set_label(loopend); if (a->tp) { @@ -8647,7 +8652,7 @@ static bool trans_LE(DisasContext *s, arg_LE *a) store_cpu_field(tcg_constant_i32(4), v7m.ltpsize); } /* End TB, continuing to following insn */ - gen_jmp_tb(s, s->base.pc_next, 1); + gen_jmp_tb(s, curr_insn_len(s), 1); return true; } @@ -8746,7 +8751,7 @@ static bool trans_CBZ(DisasContext *s, arg_CBZ *a) tcg_gen_brcondi_i32(a->nz ? TCG_COND_EQ : TCG_COND_NE, tmp, 0, s->condlabel); tcg_temp_free_i32(tmp); - gen_jmp(s, read_pc(s) + a->imm); + gen_jmp(s, jmp_diff(s, a->imm)); return true; }