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tcg: Clean up direct block chaining data fields

Browse source 
Briefly describe in a comment how direct block chaining is done. It
should help in understanding of the following data fields.

Rename some fields in TranslationBlock and TCGContext structures to
better reflect their purpose (dropping excessive 'tb_' prefix in
TranslationBlock but keeping it in TCGContext):
   tb_next_offset  =>  jmp_reset_offset
   tb_jmp_offset   =>  jmp_insn_offset
   tb_next         =>  jmp_target_addr
   jmp_next        =>  jmp_list_next
   jmp_first       =>  jmp_list_first

Avoid using a magic constant as an invalid offset which is used to
indicate that there's no n-th jump generated.

Signed-off-by: Sergey Fedorov <serge.fdrv@gmail.com>
Signed-off-by: Sergey Fedorov <sergey.fedorov@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Sergey Fedorov 2016-04-10 23:35:45 +03:00 committed by Richard Henderson
parent 7ba6a512ae
commit f309101c26
12 changed files with 96 additions and 78 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

44
include/exec/exec-all.h
View file

@ -259,20 +259,32 @@ struct TranslationBlock {
struct TranslationBlock *page_next[2];
tb_page_addr_t page_addr[2];
/* the following data are used to directly call another TB from
the code of this one. */
uint16_t tb_next_offset[2]; /* offset of original jump target */
/* The following data are used to directly call another TB from
* the code of this one. This can be done either by emitting direct or
* indirect native jump instructions. These jumps are reset so that the TB
* just continue its execution. The TB can be linked to another one by
* setting one of the jump targets (or patching the jump instruction). Only
* two of such jumps are supported.
*/
uint16_t jmp_reset_offset[2]; /* offset of original jump target */
#define TB_JMP_RESET_OFFSET_INVALID 0xffff /* indicates no jump generated */
#ifdef USE_DIRECT_JUMP
uint16_t tb_jmp_offset[2]; /* offset of jump instruction */
uint16_t jmp_insn_offset[2]; /* offset of native jump instruction */
#else
uintptr_t tb_next[2]; /* address of jump generated code */
uintptr_t jmp_target_addr[2]; /* target address for indirect jump */
#endif
/* list of TBs jumping to this one. This is a circular list using
the two least significant bits of the pointers to tell what is
the next pointer: 0 = jmp_next[0], 1 = jmp_next[1], 2 =
jmp_first */
struct TranslationBlock *jmp_next[2];
struct TranslationBlock *jmp_first;
/* Each TB has an assosiated circular list of TBs jumping to this one.
* jmp_list_first points to the first TB jumping to this one.
* jmp_list_next is used to point to the next TB in a list.
* Since each TB can have two jumps, it can participate in two lists.
* The two least significant bits of a pointer are used to choose which
* data field holds a pointer to the next TB:
* 0 => jmp_list_next[0], 1 => jmp_list_next[1], 2 => jmp_list_first.
* In other words, 0/1 tells which jump is used in the pointed TB,
* and 2 means that this is a pointer back to the target TB of this list.
*/
struct TranslationBlock *jmp_list_next[2];
struct TranslationBlock *jmp_list_first;
};
#include "qemu/thread.h"
@ -340,7 +352,7 @@ void tb_set_jmp_target1(uintptr_t jmp_addr, uintptr_t addr);
static inline void tb_set_jmp_target(TranslationBlock *tb,
int n, uintptr_t addr)
{
uint16_t offset = tb->tb_jmp_offset[n];
uint16_t offset = tb->jmp_insn_offset[n];
tb_set_jmp_target1((uintptr_t)(tb->tc_ptr + offset), addr);
}
@ -350,7 +362,7 @@ static inline void tb_set_jmp_target(TranslationBlock *tb,
static inline void tb_set_jmp_target(TranslationBlock *tb,
int n, uintptr_t addr)
{
tb->tb_next[n] = addr;
tb->jmp_target_addr[n] = addr;
}
#endif
@ -359,7 +371,7 @@ static inline void tb_add_jump(TranslationBlock *tb, int n,
TranslationBlock *tb_next)
{
/* NOTE: this test is only needed for thread safety */
if (!tb->jmp_next[n]) {
if (!tb->jmp_list_next[n]) {
qemu_log_mask_and_addr(CPU_LOG_EXEC, tb->pc,
"Linking TBs %p [" TARGET_FMT_lx
"] index %d -> %p [" TARGET_FMT_lx "]\n",
@ -369,8 +381,8 @@ static inline void tb_add_jump(TranslationBlock *tb, int n,
tb_set_jmp_target(tb, n, (uintptr_t)tb_next->tc_ptr);
/* add in TB jmp circular list */
tb->jmp_next[n] = tb_next->jmp_first;
tb_next->jmp_first = (TranslationBlock *)((uintptr_t)(tb) | (n));
tb->jmp_list_next[n] = tb_next->jmp_list_first;
tb_next->jmp_list_first = (TranslationBlock *)((uintptr_t)tb | n);
}
}

7
tcg/aarch64/tcg-target.inc.c
View file

@ -1306,12 +1306,13 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc,
#ifndef USE_DIRECT_JUMP
#error "USE_DIRECT_JUMP required for aarch64"
#endif
tcg_debug_assert(s->tb_jmp_offset != NULL); /* consistency for USE_DIRECT_JUMP */
s->tb_jmp_offset[a0] = tcg_current_code_size(s);
/* consistency for USE_DIRECT_JUMP */
tcg_debug_assert(s->tb_jmp_insn_offset != NULL);
s->tb_jmp_insn_offset[a0] = tcg_current_code_size(s);
/* actual branch destination will be patched by
aarch64_tb_set_jmp_target later, beware retranslation. */
tcg_out_goto_noaddr(s);
s->tb_next_offset[a0] = tcg_current_code_size(s);
s->tb_jmp_reset_offset[a0] = tcg_current_code_size(s);
break;
case INDEX_op_br:

8
tcg/arm/tcg-target.inc.c
View file

@ -1665,17 +1665,17 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
tcg_out_goto(s, COND_AL, tb_ret_addr);
break;
case INDEX_op_goto_tb:
if (s->tb_jmp_offset) {
if (s->tb_jmp_insn_offset) {
/* Direct jump method */
s->tb_jmp_offset[args[0]] = tcg_current_code_size(s);
s->tb_jmp_insn_offset[args[0]] = tcg_current_code_size(s);
tcg_out_b_noaddr(s, COND_AL);
} else {
/* Indirect jump method */
intptr_t ptr = (intptr_t)(s->tb_next + args[0]);
intptr_t ptr = (intptr_t)(s->tb_jmp_target_addr + args[0]);
tcg_out_movi32(s, COND_AL, TCG_REG_R0, ptr & ~0xfff);
tcg_out_ld32_12(s, COND_AL, TCG_REG_PC, TCG_REG_R0, ptr & 0xfff);
}
s->tb_next_offset[args[0]] = tcg_current_code_size(s);
s->tb_jmp_reset_offset[args[0]] = tcg_current_code_size(s);
break;
case INDEX_op_br:
tcg_out_goto_label(s, COND_AL, arg_label(args[0]));

8
tcg/i386/tcg-target.inc.c
View file

@ -1790,7 +1790,7 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
tcg_out_jmp(s, tb_ret_addr);
break;
case INDEX_op_goto_tb:
if (s->tb_jmp_offset) {
if (s->tb_jmp_insn_offset) {
/* direct jump method */
int gap;
/* jump displacement must be aligned for atomic patching;
@ -1801,14 +1801,14 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
tcg_out_nopn(s, gap - 1);
}
tcg_out8(s, OPC_JMP_long); /* jmp im */
s->tb_jmp_offset[args[0]] = tcg_current_code_size(s);
s->tb_jmp_insn_offset[args[0]] = tcg_current_code_size(s);
tcg_out32(s, 0);
} else {
/* indirect jump method */
tcg_out_modrm_offset(s, OPC_GRP5, EXT5_JMPN_Ev, -1,
(intptr_t)(s->tb_next + args[0]));
(intptr_t)(s->tb_jmp_target_addr + args[0]));
}
s->tb_next_offset[args[0]] = tcg_current_code_size(s);
s->tb_jmp_reset_offset[args[0]] = tcg_current_code_size(s);
break;
case INDEX_op_br:
tcg_out_jxx(s, JCC_JMP, arg_label(args[0]), 0);

6
tcg/ia64/tcg-target.inc.c
View file

@ -881,13 +881,13 @@ static void tcg_out_exit_tb(TCGContext *s, tcg_target_long arg)
static inline void tcg_out_goto_tb(TCGContext *s, TCGArg arg)
{
if (s->tb_jmp_offset) {
if (s->tb_jmp_insn_offset) {
/* direct jump method */
tcg_abort();
} else {
/* indirect jump method */
tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_R2,
(tcg_target_long)(s->tb_next + arg));
(tcg_target_long)(s->tb_jmp_target_addr + arg));
tcg_out_bundle(s, MmI,
tcg_opc_m1 (TCG_REG_P0, OPC_LD8_M1,
TCG_REG_R2, TCG_REG_R2),
@ -900,7 +900,7 @@ static inline void tcg_out_goto_tb(TCGContext *s, TCGArg arg)
tcg_opc_b4 (TCG_REG_P0, OPC_BR_SPTK_MANY_B4,
TCG_REG_B6));
}
s->tb_next_offset[arg] = tcg_current_code_size(s);
s->tb_jmp_reset_offset[arg] = tcg_current_code_size(s);
}
static inline void tcg_out_jmp(TCGContext *s, TCGArg addr)

8
tcg/mips/tcg-target.inc.c
View file

@ -1397,19 +1397,19 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
}
break;
case INDEX_op_goto_tb:
if (s->tb_jmp_offset) {
if (s->tb_jmp_insn_offset) {
/* direct jump method */
s->tb_jmp_offset[a0] = tcg_current_code_size(s);
s->tb_jmp_insn_offset[a0] = tcg_current_code_size(s);
/* Avoid clobbering the address during retranslation. */
tcg_out32(s, OPC_J | (*(uint32_t *)s->code_ptr & 0x3ffffff));
} else {
/* indirect jump method */
tcg_out_ld(s, TCG_TYPE_PTR, TCG_TMP0, TCG_REG_ZERO,
(uintptr_t)(s->tb_next + a0));
(uintptr_t)(s->tb_jmp_target_addr + a0));
tcg_out_opc_reg(s, OPC_JR, 0, TCG_TMP0, 0);
}
tcg_out_nop(s);
s->tb_next_offset[a0] = tcg_current_code_size(s);
s->tb_jmp_reset_offset[a0] = tcg_current_code_size(s);
break;
case INDEX_op_br:
tcg_out_brcond(s, TCG_COND_EQ, TCG_REG_ZERO, TCG_REG_ZERO,

6
tcg/ppc/tcg-target.inc.c
View file

@ -1902,14 +1902,14 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, const TCGArg *args,
tcg_out_b(s, 0, tb_ret_addr);
break;
case INDEX_op_goto_tb:
tcg_debug_assert(s->tb_jmp_offset);
tcg_debug_assert(s->tb_jmp_insn_offset);
/* Direct jump. */
#ifdef __powerpc64__
/* Ensure the next insns are 8-byte aligned. */
if ((uintptr_t)s->code_ptr & 7) {
tcg_out32(s, NOP);
}
s->tb_jmp_offset[args[0]] = tcg_current_code_size(s);
s->tb_jmp_insn_offset[args[0]] = tcg_current_code_size(s);
/* To be replaced by either a branch+nop or a load into TMP1. */
s->code_ptr += 2;
tcg_out32(s, MTSPR | RS(TCG_REG_TMP1) | CTR);
@ -1918,7 +1918,7 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, const TCGArg *args,
/* To be replaced by a branch. */
s->code_ptr++;
#endif
s->tb_next_offset[args[0]] = tcg_current_code_size(s);
s->tb_jmp_reset_offset[args[0]] = tcg_current_code_size(s);
break;
case INDEX_op_br:
{

11
tcg/s390/tcg-target.inc.c
View file

@ -1717,7 +1717,7 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
break;
case INDEX_op_goto_tb:
if (s->tb_jmp_offset) {
if (s->tb_jmp_insn_offset) {
/* branch displacement must be aligned for atomic patching;
* see if we need to add extra nop before branch
*/
@ -1725,15 +1725,16 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
tcg_out16(s, NOP);
}
tcg_out16(s, RIL_BRCL | (S390_CC_ALWAYS << 4));
s->tb_jmp_offset[args[0]] = tcg_current_code_size(s);
s->tb_jmp_insn_offset[args[0]] = tcg_current_code_size(s);
s->code_ptr += 2;
} else {
/* load address stored at s->tb_next + args[0] */
tcg_out_ld_abs(s, TCG_TYPE_PTR, TCG_TMP0, s->tb_next + args[0]);
/* load address stored at s->tb_jmp_target_addr + args[0] */
tcg_out_ld_abs(s, TCG_TYPE_PTR, TCG_TMP0,
s->tb_jmp_target_addr + args[0]);
/* and go there */
tcg_out_insn(s, RR, BCR, S390_CC_ALWAYS, TCG_TMP0);
}
s->tb_next_offset[args[0]] = tcg_current_code_size(s);
s->tb_jmp_reset_offset[args[0]] = tcg_current_code_size(s);
break;
OP_32_64(ld8u):

9
tcg/sparc/tcg-target.inc.c
View file

@ -1229,18 +1229,19 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc,
}
break;
case INDEX_op_goto_tb:
if (s->tb_jmp_offset) {
if (s->tb_jmp_insn_offset) {
/* direct jump method */
s->tb_jmp_offset[a0] = tcg_current_code_size(s);
s->tb_jmp_insn_offset[a0] = tcg_current_code_size(s);
/* Make sure to preserve links during retranslation. */
tcg_out32(s, CALL | (*s->code_ptr & ~INSN_OP(-1)));
} else {
/* indirect jump method */
tcg_out_ld_ptr(s, TCG_REG_T1, (uintptr_t)(s->tb_next + a0));
tcg_out_ld_ptr(s, TCG_REG_T1,
(uintptr_t)(s->tb_jmp_target_addr + a0));
tcg_out_arithi(s, TCG_REG_G0, TCG_REG_T1, 0, JMPL);
}
tcg_out_nop(s);
s->tb_next_offset[a0] = tcg_current_code_size(s);
s->tb_jmp_reset_offset[a0] = tcg_current_code_size(s);
break;
case INDEX_op_br:
tcg_out_bpcc(s, COND_A, BPCC_PT, arg_label(a0));

6
tcg/tcg.h
View file

@ -510,9 +510,9 @@ struct TCGContext {
/* goto_tb support */
tcg_insn_unit *code_buf;
uintptr_t *tb_next;
uint16_t *tb_next_offset;
uint16_t *tb_jmp_offset; /* != NULL if USE_DIRECT_JUMP */
uint16_t *tb_jmp_reset_offset; /* tb->jmp_reset_offset */
uint16_t *tb_jmp_insn_offset; /* tb->jmp_insn_offset if USE_DIRECT_JUMP */
uintptr_t *tb_jmp_target_addr; /* tb->jmp_target_addr if !USE_DIRECT_JUMP */
/* liveness analysis */
uint16_t *op_dead_args; /* for each operation, each bit tells if the

10
tcg/tci/tcg-target.inc.c
View file

@ -553,19 +553,19 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, const TCGArg *args,
tcg_out64(s, args[0]);
break;
case INDEX_op_goto_tb:
if (s->tb_jmp_offset) {
if (s->tb_jmp_insn_offset) {
/* Direct jump method. */
tcg_debug_assert(args[0] < ARRAY_SIZE(s->tb_jmp_offset));
tcg_debug_assert(args[0] < ARRAY_SIZE(s->tb_jmp_insn_offset));
/* Align for atomic patching and thread safety */
s->code_ptr = QEMU_ALIGN_PTR_UP(s->code_ptr, 4);
s->tb_jmp_offset[args[0]] = tcg_current_code_size(s);
s->tb_jmp_insn_offset[args[0]] = tcg_current_code_size(s);
tcg_out32(s, 0);
} else {
/* Indirect jump method. */
TODO();
}
tcg_debug_assert(args[0] < ARRAY_SIZE(s->tb_next_offset));
s->tb_next_offset[args[0]] = tcg_current_code_size(s);
tcg_debug_assert(args[0] < ARRAY_SIZE(s->tb_jmp_reset_offset));
s->tb_jmp_reset_offset[args[0]] = tcg_current_code_size(s);
break;
case INDEX_op_br:
tci_out_label(s, arg_label(args[0]));

51
translate-all.c
View file

@ -931,7 +931,7 @@ static inline void tb_jmp_remove(TranslationBlock *tb, int n)
TranslationBlock *tb1, **ptb;
unsigned int n1;
ptb = &tb->jmp_next[n];
ptb = &tb->jmp_list_next[n];
tb1 = *ptb;
if (tb1) {
/* find tb(n) in circular list */
@ -943,15 +943,15 @@ static inline void tb_jmp_remove(TranslationBlock *tb, int n)
break;
}
if (n1 == 2) {
ptb = &tb1->jmp_first;
ptb = &tb1->jmp_list_first;
} else {
ptb = &tb1->jmp_next[n1];
ptb = &tb1->jmp_list_next[n1];
}
}
/* now we can suppress tb(n) from the list */
*ptb = tb->jmp_next[n];
*ptb = tb->jmp_list_next[n];
tb->jmp_next[n] = NULL;
tb->jmp_list_next[n] = NULL;
}
}
@ -959,7 +959,8 @@ static inline void tb_jmp_remove(TranslationBlock *tb, int n)
another TB */
static inline void tb_reset_jump(TranslationBlock *tb, int n)
{
tb_set_jmp_target(tb, n, (uintptr_t)(tb->tc_ptr + tb->tb_next_offset[n]));
uintptr_t addr = (uintptr_t)(tb->tc_ptr + tb->jmp_reset_offset[n]);
tb_set_jmp_target(tb, n, addr);
}
/* invalidate one TB */
@ -1003,19 +1004,21 @@ void tb_phys_invalidate(TranslationBlock *tb, tb_page_addr_t page_addr)
tb_jmp_remove(tb, 1);
/* suppress any remaining jumps to this TB */
tb1 = tb->jmp_first;
tb1 = tb->jmp_list_first;
for (;;) {
n1 = (uintptr_t)tb1 & 3;
if (n1 == 2) {
break;
}
tb1 = (TranslationBlock *)((uintptr_t)tb1 & ~3);
tb2 = tb1->jmp_next[n1];
tb2 = tb1->jmp_list_next[n1];
tb_reset_jump(tb1, n1);
tb1->jmp_next[n1] = NULL;
tb1->jmp_list_next[n1] = NULL;
tb1 = tb2;
}
tb->jmp_first = (TranslationBlock *)((uintptr_t)tb | 2); /* fail safe */
/* fail safe */
tb->jmp_list_first = (TranslationBlock *)((uintptr_t)tb | 2);
tcg_ctx.tb_ctx.tb_phys_invalidate_count++;
}
@ -1100,15 +1103,15 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
trace_translate_block(tb, tb->pc, tb->tc_ptr);
/* generate machine code */
tb->tb_next_offset[0] = 0xffff;
tb->tb_next_offset[1] = 0xffff;
tcg_ctx.tb_next_offset = tb->tb_next_offset;
tb->jmp_reset_offset[0] = TB_JMP_RESET_OFFSET_INVALID;
tb->jmp_reset_offset[1] = TB_JMP_RESET_OFFSET_INVALID;
tcg_ctx.tb_jmp_reset_offset = tb->jmp_reset_offset;
#ifdef USE_DIRECT_JUMP
tcg_ctx.tb_jmp_offset = tb->tb_jmp_offset;
tcg_ctx.tb_next = NULL;
tcg_ctx.tb_jmp_insn_offset = tb->jmp_insn_offset;
tcg_ctx.tb_jmp_target_addr = NULL;
#else
tcg_ctx.tb_jmp_offset = NULL;
tcg_ctx.tb_next = tb->tb_next;
tcg_ctx.tb_jmp_insn_offset = NULL;
tcg_ctx.tb_jmp_target_addr = tb->jmp_target_addr;
#endif
#ifdef CONFIG_PROFILER
@ -1489,15 +1492,15 @@ static void tb_link_page(TranslationBlock *tb, tb_page_addr_t phys_pc,
tb->page_addr[1] = -1;
}
tb->jmp_first = (TranslationBlock *)((uintptr_t)tb | 2);
tb->jmp_next[0] = NULL;
tb->jmp_next[1] = NULL;
tb->jmp_list_first = (TranslationBlock *)((uintptr_t)tb | 2);
tb->jmp_list_next[0] = NULL;
tb->jmp_list_next[1] = NULL;
/* init original jump addresses */
if (tb->tb_next_offset[0] != 0xffff) {
if (tb->jmp_reset_offset[0] != TB_JMP_RESET_OFFSET_INVALID) {
tb_reset_jump(tb, 0);
}
if (tb->tb_next_offset[1] != 0xffff) {
if (tb->jmp_reset_offset[1] != TB_JMP_RESET_OFFSET_INVALID) {
tb_reset_jump(tb, 1);
}
@ -1690,9 +1693,9 @@ void dump_exec_info(FILE *f, fprintf_function cpu_fprintf)
if (tb->page_addr[1] != -1) {
cross_page++;
}
if (tb->tb_next_offset[0] != 0xffff) {
if (tb->jmp_reset_offset[0] != TB_JMP_RESET_OFFSET_INVALID) {
direct_jmp_count++;
if (tb->tb_next_offset[1] != 0xffff) {
if (tb->jmp_reset_offset[1] != TB_JMP_RESET_OFFSET_INVALID) {
direct_jmp2_count++;
}
}