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Re: [Qemu-devel] [PATCH v2 11/14] tcg: Implement indirect memory registe
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH v2 11/14] tcg: Implement indirect memory registers |
Date: |
Thu, 31 Dec 2015 12:54:30 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On 2015-12-17 12:00, Richard Henderson wrote:
> That is, global_mem registers whose base is another global_mem
> register, rather than a fixed register.
>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
> tcg/tcg.c | 95
> ++++++++++++++++++++++++++++++++++++++++++++-------------------
> tcg/tcg.h | 2 ++
> 2 files changed, 68 insertions(+), 29 deletions(-)
>
> diff --git a/tcg/tcg.c b/tcg/tcg.c
> index c51e0ec..7150a3f 100644
> --- a/tcg/tcg.c
> +++ b/tcg/tcg.c
> @@ -509,17 +509,23 @@ int tcg_global_mem_new_internal(TCGType type, TCGv_ptr
> base,
> TCGContext *s = &tcg_ctx;
> TCGTemp *base_ts = &s->temps[GET_TCGV_PTR(base)];
> TCGTemp *ts = tcg_global_alloc(s);
> - int bigendian = 0;
> + int indirect_reg = 0, bigendian = 0;
> #ifdef HOST_WORDS_BIGENDIAN
> bigendian = 1;
> #endif
>
> + if (!base_ts->fixed_reg) {
> + indirect_reg = 1;
> + base_ts->indirect_base = 1;
> + }
> +
> if (TCG_TARGET_REG_BITS == 32 && type == TCG_TYPE_I64) {
> TCGTemp *ts2 = tcg_global_alloc(s);
> char buf[64];
>
> ts->base_type = TCG_TYPE_I64;
> ts->type = TCG_TYPE_I32;
> + ts->indirect_reg = indirect_reg;
Do we really need to add this new bit, while we can simply test
ts->mem_base->fixed_reg? This means one more derefence, but anyway it
has to be done later when calling temp_load?
> ts->mem_allocated = 1;
> ts->mem_base = base_ts;
> ts->mem_offset = offset + bigendian * 4;
> @@ -1781,13 +1803,16 @@ static inline void temp_save(TCGContext *s, TCGTemp
> *ts,
> TCGRegSet allocated_regs)
> {
> #ifdef USE_LIVENESS_ANALYSIS
> - /* The liveness analysis already ensures that globals are back
> - in memory. Keep an assert for safety. */
> - tcg_debug_assert(ts->val_type == TEMP_VAL_MEM || ts->fixed_reg);
> -#else
> + /* ??? Liveness does not yet incorporate indirect bases. */
> + if (!ts->indirect_base) {
> + /* The liveness analysis already ensures that globals are back
> + in memory. Keep an assert for safety. */
> + tcg_debug_assert(ts->val_type == TEMP_VAL_MEM || ts->fixed_reg);
> + return;
> + }
This basically disables the assert. What does it mean in practice? Can
it generates bad code?
> +#endif
> temp_sync(s, ts, allocated_regs);
> temp_dead(s, ts);
> -#endif
> }
>
> /* save globals to their canonical location and assume they can be
> @@ -1812,12 +1837,15 @@ static void sync_globals(TCGContext *s, TCGRegSet
> allocated_regs)
> for (i = 0; i < s->nb_globals; i++) {
> TCGTemp *ts = &s->temps[i];
> #ifdef USE_LIVENESS_ANALYSIS
> - tcg_debug_assert(ts->val_type != TEMP_VAL_REG
> - || ts->fixed_reg
> - || ts->mem_coherent);
> -#else
> - temp_sync(s, ts, allocated_regs);
> + /* ??? Liveness does not yet incorporate indirect bases. */
> + if (!ts->indirect_base) {
> + tcg_debug_assert(ts->val_type != TEMP_VAL_REG
> + || ts->fixed_reg
> + || ts->mem_coherent);
> + continue;
> + }
Same here.
> #endif
> + temp_sync(s, ts, allocated_regs);
> }
> }
>
> @@ -1833,12 +1861,15 @@ static void tcg_reg_alloc_bb_end(TCGContext *s,
> TCGRegSet allocated_regs)
> temp_save(s, ts, allocated_regs);
> } else {
> #ifdef USE_LIVENESS_ANALYSIS
> - /* The liveness analysis already ensures that temps are dead.
> - Keep an assert for safety. */
> - assert(ts->val_type == TEMP_VAL_DEAD);
> -#else
> - temp_dead(s, ts);
> + /* ??? Liveness does not yet incorporate indirect bases. */
> + if (!ts->indirect_base) {
> + /* The liveness analysis already ensures that temps are dead.
> + Keep an assert for safety. */
> + assert(ts->val_type == TEMP_VAL_DEAD);
> + continue;
> + }
And here.
> #endif
> + temp_dead(s, ts);
> }
> }
>
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
address@hidden http://www.aurel32.net
- Re: [Qemu-devel] [PATCH v2 08/14] tcg: Change temp_sync argument to TCGTemp, (continued)
- [Qemu-devel] [PATCH v2 06/14] tcg: Change reg_to_temp to TCGTemp pointer, Richard Henderson, 2015/12/17
- [Qemu-devel] [PATCH v2 09/14] tcg: Change temp_save argument to TCGTemp, Richard Henderson, 2015/12/17
- [Qemu-devel] [PATCH v2 13/14] target-sparc: Tidy global register initialization, Richard Henderson, 2015/12/17
- [Qemu-devel] [PATCH v2 12/14] tcg: Allocate indirect_base temporaries in a different order, Richard Henderson, 2015/12/17
- [Qemu-devel] [PATCH v2 10/14] tcg: Introduce temp_load, Richard Henderson, 2015/12/17
- [Qemu-devel] [PATCH v2 11/14] tcg: Implement indirect memory registers, Richard Henderson, 2015/12/17
- Re: [Qemu-devel] [PATCH v2 11/14] tcg: Implement indirect memory registers,
Aurelien Jarno <=
- [Qemu-devel] [PATCH v2 14/14] target-sparc: Use global registers for the register window, Richard Henderson, 2015/12/17