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tcg: Add TranslationBlock.jmp_insn_offset 

Stop overloading jmp_target_arg for both offset and address,
depending on TCG_TARGET_HAS_direct_jump.  Instead, add a new
field to hold the jump insn offset and always set the target
address in jmp_target_addr[].  This will allow a tcg backend
to use either direct or indirect depending on displacement.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2022-11-26 18:54:23 -08:00
parent b7e4afbd9f
commit 9da6079b26
3 changed files with 8 additions and 6 deletions
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5
accel/tcg/cpu-exec.c
View File

@ -572,14 +572,13 @@ void cpu_exec_step_atomic(CPUState *cpu)
void tb_set_jmp_target(TranslationBlock *tb, int n, uintptr_t addr)
{
tb->jmp_target_addr[n] = addr;
if (TCG_TARGET_HAS_direct_jump) {
uintptr_t offset = tb->jmp_target_arg[n];
uintptr_t offset = tb->jmp_insn_offset[n];
uintptr_t tc_ptr = (uintptr_t)tb->tc.ptr;
uintptr_t jmp_rx = tc_ptr + offset;
uintptr_t jmp_rw = jmp_rx - tcg_splitwx_diff;
tb_target_set_jmp_target(tc_ptr, jmp_rx, jmp_rw, addr);
} else {
tb->jmp_target_arg[n] = addr;
}
}

3
include/exec/exec-all.h
View File

@ -587,7 +587,8 @@ struct TranslationBlock {
*/
#define TB_JMP_OFFSET_INVALID 0xffff /* indicates no jump generated */
uint16_t jmp_reset_offset[2]; /* offset of original jump target */
uintptr_t jmp_target_arg[2]; /* target address or offset */
uint16_t jmp_insn_offset[2]; /* offset of direct jump insn */
uintptr_t jmp_target_addr[2]; /* target address */
/*
* Each TB has a NULL-terminated list (jmp_list_head) of incoming jumps.

6
tcg/tcg.c
View File

@ -321,7 +321,7 @@ static void G_GNUC_UNUSED set_jmp_insn_offset(TCGContext *s, int which)
* tcg_gen_code, where we bound tcg_current_code_size to UINT16_MAX.
*/
tcg_debug_assert(TCG_TARGET_HAS_direct_jump);
s->gen_tb->jmp_target_arg[which] = tcg_current_code_size(s);
s->gen_tb->jmp_insn_offset[which] = tcg_current_code_size(s);
}
static uintptr_t G_GNUC_UNUSED get_jmp_target_addr(TCGContext *s, int which)
@ -330,7 +330,7 @@ static uintptr_t G_GNUC_UNUSED get_jmp_target_addr(TCGContext *s, int which)
* Return the read-execute version of the pointer, for the benefit
* of any pc-relative addressing mode.
*/
return (uintptr_t)tcg_splitwx_to_rx(s->gen_tb->jmp_target_arg + which);
return (uintptr_t)tcg_splitwx_to_rx(&s->gen_tb->jmp_target_addr[which]);
}
/* Signal overflow, starting over with fewer guest insns. */
@ -4668,6 +4668,8 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb, target_ulong pc_start)
/* Initialize goto_tb jump offsets. */
tb->jmp_reset_offset[0] = TB_JMP_OFFSET_INVALID;
tb->jmp_reset_offset[1] = TB_JMP_OFFSET_INVALID;
tb->jmp_insn_offset[0] = TB_JMP_OFFSET_INVALID;
tb->jmp_insn_offset[1] = TB_JMP_OFFSET_INVALID;
tcg_reg_alloc_start(s);