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target/arm: Tidy TBI handling in gen_a64_set_pc 

We can perform this with fewer operations.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190108223129.5570-32-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Richard Henderson 2019-01-21 10:23:13 +00:00 committed by Peter Maydell
parent 1ae9cfbd47
commit 8733d762d5
1 changed files with 21 additions and 41 deletions
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62
target/arm/translate-a64.c
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@ -261,7 +261,7 @@ void gen_a64_set_pc_im(uint64_t val)
/* Load the PC from a generic TCG variable. /* Load the PC from a generic TCG variable.
* *
* If address tagging is enabled via the TCR TBI bits, then loading * If address tagging is enabled via the TCR TBI bits, then loading
* an address into the PC will clear out any tag in the it: * an address into the PC will clear out any tag in it:
* + for EL2 and EL3 there is only one TBI bit, and if it is set * + for EL2 and EL3 there is only one TBI bit, and if it is set
* then the address is zero-extended, clearing bits [63:56] * then the address is zero-extended, clearing bits [63:56]
* + for EL0 and EL1, TBI0 controls addresses with bit 55 == 0 * + for EL0 and EL1, TBI0 controls addresses with bit 55 == 0
@ -280,54 +280,34 @@ static void gen_a64_set_pc(DisasContext *s, TCGv_i64 src)
int tbi = s->tbii; int tbi = s->tbii;
if (s->current_el <= 1) { if (s->current_el <= 1) {
/* Test if NEITHER or BOTH TBI values are set. If so, no need to if (tbi != 0) {
* examine bit 55 of address, can just generate code. /* Sign-extend from bit 55. */
* If mixed, then test via generated code tcg_gen_sextract_i64(cpu_pc, src, 0, 56);
*/
if (tbi == 3) {
TCGv_i64 tmp_reg = tcg_temp_new_i64();
/* Both bits set, sign extension from bit 55 into [63:56] will
* cover both cases
*/
tcg_gen_shli_i64(tmp_reg, src, 8);
tcg_gen_sari_i64(cpu_pc, tmp_reg, 8);
tcg_temp_free_i64(tmp_reg);
} else if (tbi == 0) {
/* Neither bit set, just load it as-is */
tcg_gen_mov_i64(cpu_pc, src);
} else {
TCGv_i64 tcg_tmpval = tcg_temp_new_i64();
TCGv_i64 tcg_bit55 = tcg_temp_new_i64();
TCGv_i64 tcg_zero = tcg_const_i64(0);
tcg_gen_andi_i64(tcg_bit55, src, (1ull << 55)); if (tbi != 3) {
TCGv_i64 tcg_zero = tcg_const_i64(0);
if (tbi == 1) { /*
/* tbi0==1, tbi1==0, so 0-fill upper byte if bit 55 = 0 */ * The two TBI bits differ.
tcg_gen_andi_i64(tcg_tmpval, src, * If tbi0, then !tbi1: only use the extension if positive.
0x00FFFFFFFFFFFFFFull); * if !tbi0, then tbi1: only use the extension if negative.
tcg_gen_movcond_i64(TCG_COND_EQ, cpu_pc, tcg_bit55, tcg_zero, */
tcg_tmpval, src); tcg_gen_movcond_i64(tbi == 1 ? TCG_COND_GE : TCG_COND_LT,
} else { cpu_pc, cpu_pc, tcg_zero, cpu_pc, src);
/* tbi0==0, tbi1==1, so 1-fill upper byte if bit 55 = 1 */ tcg_temp_free_i64(tcg_zero);
tcg_gen_ori_i64(tcg_tmpval, src,
0xFF00000000000000ull);
tcg_gen_movcond_i64(TCG_COND_NE, cpu_pc, tcg_bit55, tcg_zero,
tcg_tmpval, src);
} }
tcg_temp_free_i64(tcg_zero); return;
tcg_temp_free_i64(tcg_bit55);
tcg_temp_free_i64(tcg_tmpval);
} }
} else { /* EL > 1 */ } else {
if (tbi != 0) { if (tbi != 0) {
/* Force tag byte to all zero */ /* Force tag byte to all zero */
tcg_gen_andi_i64(cpu_pc, src, 0x00FFFFFFFFFFFFFFull); tcg_gen_extract_i64(cpu_pc, src, 0, 56);
} else { return;
/* Load unmodified address */
tcg_gen_mov_i64(cpu_pc, src);
} }
} }
/* Load unmodified address */
tcg_gen_mov_i64(cpu_pc, src);
} }
typedef struct DisasCompare64 { typedef struct DisasCompare64 {