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target-arm: A64: add support for B and BL insns 

Implement the B and BL instructions (PC relative branches and calls).

For convenience in managing TCG temporaries which might be generated
if a source register is the zero-register XZR, we provide a simple
mechanism for creating a new temp which is automatically freed at the
end of decode of the instruction.

Signed-off-by: Alexander Graf <agraf@suse.de>
[claudio: renamed functions, adapted to new decoder layout]
Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Alexander Graf 2013-12-17 19:42:32 +00:00 committed by Peter Maydell
parent 87462e0f41
commit 11e169de99
2 changed files with 65 additions and 2 deletions
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64
target-arm/translate-a64.c
View File

@ -160,16 +160,71 @@ static void unallocated_encoding(DisasContext *s)
unallocated_encoding(s); \
} while (0);
static void init_tmp_a64_array(DisasContext *s)
{
#ifdef CONFIG_DEBUG_TCG
int i;
for (i = 0; i < ARRAY_SIZE(s->tmp_a64); i++) {
TCGV_UNUSED_I64(s->tmp_a64[i]);
}
#endif
s->tmp_a64_count = 0;
}
static void free_tmp_a64(DisasContext *s)
{
int i;
for (i = 0; i < s->tmp_a64_count; i++) {
tcg_temp_free_i64(s->tmp_a64[i]);
}
init_tmp_a64_array(s);
}
static TCGv_i64 new_tmp_a64(DisasContext *s)
{
assert(s->tmp_a64_count < TMP_A64_MAX);
return s->tmp_a64[s->tmp_a64_count++] = tcg_temp_new_i64();
}
static TCGv_i64 new_tmp_a64_zero(DisasContext *s)
{
TCGv_i64 t = new_tmp_a64(s);
tcg_gen_movi_i64(t, 0);
return t;
}
static TCGv_i64 cpu_reg(DisasContext *s, int reg)
{
if (reg == 31) {
return new_tmp_a64_zero(s);
} else {
return cpu_X[reg];
}
}
/*
* the instruction disassembly implemented here matches
* the instruction encoding classifications in chapter 3 (C3)
* of the ARM Architecture Reference Manual (DDI0487A_a)
*/
/* Unconditional branch (immediate) */
/* C3.2.7 Unconditional branch (immediate)
* 31 30 26 25 0
* +----+-----------+-------------------------------------+
* | op | 0 0 1 0 1 | imm26 |
* +----+-----------+-------------------------------------+
*/
static void disas_uncond_b_imm(DisasContext *s, uint32_t insn)
{
unsupported_encoding(s, insn);
uint64_t addr = s->pc + sextract32(insn, 0, 26) * 4 - 4;
if (insn & (1 << 31)) {
/* C5.6.26 BL Branch with link */
tcg_gen_movi_i64(cpu_reg(s, 30), s->pc);
}
/* C5.6.20 B Branch / C5.6.26 BL Branch with link */
gen_goto_tb(s, 0, addr);
}
/* Compare & branch (immediate) */
@ -651,6 +706,9 @@ static void disas_a64_insn(CPUARMState *env, DisasContext *s)
assert(FALSE); /* all 15 cases should be handled above */
break;
}
/* if we allocated any temporaries, free them here */
free_tmp_a64(s);
}
void gen_intermediate_code_internal_a64(ARMCPU *cpu,
@ -691,6 +749,8 @@ void gen_intermediate_code_internal_a64(ARMCPU *cpu,
dc->vec_len = 0;
dc->vec_stride = 0;
init_tmp_a64_array(dc);
next_page_start = (pc_start & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
lj = -1;
num_insns = 0;

3
target-arm/translate.h
View File

@ -24,6 +24,9 @@ typedef struct DisasContext {
int vec_len;
int vec_stride;
int aarch64;
#define TMP_A64_MAX 16
int tmp_a64_count;
TCGv_i64 tmp_a64[TMP_A64_MAX];
} DisasContext;
extern TCGv_ptr cpu_env;