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tcg-aarch64: Use CBZ and CBNZ

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A compare and branch against zero happens at the start of
every single TB.

Reviewed-by: Claudio Fontana <claudio.fontana@huawei.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2014-02-27 19:55:30 -05:00 committed by Richard Henderson
parent cae1f6f3e6
commit 3d9e69a238
1 changed files with 24 additions and 2 deletions
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26
tcg/aarch64/tcg-target.c
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@ -270,6 +270,10 @@ enum aarch64_ldst_op_type { /* type of operation */
use the section number of the architecture reference manual in which the
instruction group is described. */
typedef enum {
/* Compare and branch (immediate). */
I3201_CBZ = 0x34000000,
I3201_CBNZ = 0x35000000,
/* Conditional branch (immediate). */
I3202_B_C = 0x54000000,
@ -433,6 +437,12 @@ static inline uint32_t tcg_in32(TCGContext *s)
#define tcg_out_insn(S, FMT, OP, ...) \
glue(tcg_out_insn_,FMT)(S, glue(glue(glue(I,FMT),_),OP), ## __VA_ARGS__)
static void tcg_out_insn_3201(TCGContext *s, AArch64Insn insn, TCGType ext,
TCGReg rt, int imm19)
{
tcg_out32(s, insn | ext << 31 | (imm19 & 0x7ffff) << 5 | rt);
}
static void tcg_out_insn_3202(TCGContext *s, AArch64Insn insn,
TCGCond c, int imm19)
{
@ -913,8 +923,14 @@ static void tcg_out_brcond(TCGContext *s, TCGMemOp ext, TCGCond c, TCGArg a,
{
TCGLabel *l = &s->labels[label];
intptr_t offset;
bool need_cmp;
tcg_out_cmp(s, ext, a, b, b_const);
if (b_const && b == 0 && (c == TCG_COND_EQ || c == TCG_COND_NE)) {
need_cmp = false;
} else {
need_cmp = true;
tcg_out_cmp(s, ext, a, b, b_const);
}
if (!l->has_value) {
tcg_out_reloc(s, s->code_ptr, R_AARCH64_CONDBR19, label, 0);
@ -925,7 +941,13 @@ static void tcg_out_brcond(TCGContext *s, TCGMemOp ext, TCGCond c, TCGArg a,
assert(offset >= -0x40000 && offset < 0x40000);
}
tcg_out_insn(s, 3202, B_C, c, offset);
if (need_cmp) {
tcg_out_insn(s, 3202, B_C, c, offset);
} else if (c == TCG_COND_EQ) {
tcg_out_insn(s, 3201, CBZ, ext, a, offset);
} else {
tcg_out_insn(s, 3201, CBNZ, ext, a, offset);
}
}
static inline void tcg_out_rev(TCGContext *s, TCGType ext,