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tcg/arm: Use constant pool for movi 

Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2017-07-27 20:47:56 -07:00
parent 2a8ab93c6b
commit 880ad9626c
2 changed files with 75 additions and 18 deletions
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1
tcg/arm/tcg-target.h
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@ -143,5 +143,6 @@ void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t);
#ifdef CONFIG_SOFTMMU
#define TCG_TARGET_NEED_LDST_LABELS
#endif
#define TCG_TARGET_NEED_POOL_LABELS
#endif

92
tcg/arm/tcg-target.inc.c
View File

@ -23,6 +23,7 @@
*/
#include "elf.h"
#include "tcg-pool.inc.c"
int arm_arch = __ARM_ARCH;
@ -203,9 +204,39 @@ static inline void reloc_pc24_atomic(tcg_insn_unit *code_ptr, tcg_insn_unit *tar
static void patch_reloc(tcg_insn_unit *code_ptr, int type,
intptr_t value, intptr_t addend)
{
tcg_debug_assert(type == R_ARM_PC24);
tcg_debug_assert(addend == 0);
reloc_pc24(code_ptr, (tcg_insn_unit *)value);
if (type == R_ARM_PC24) {
reloc_pc24(code_ptr, (tcg_insn_unit *)value);
} else if (type == R_ARM_PC13) {
intptr_t diff = value - (uintptr_t)(code_ptr + 2);
tcg_insn_unit insn = *code_ptr;
bool u;
if (diff >= -0xfff && diff <= 0xfff) {
u = (diff >= 0);
if (!u) {
diff = -diff;
}
} else {
int rd = extract32(insn, 12, 4);
int rt = rd == TCG_REG_PC ? TCG_REG_TMP : rd;
assert(diff >= 0x1000 && diff < 0x100000);
/* add rt, pc, #high */
*code_ptr++ = ((insn & 0xf0000000) | (1 << 25) | ARITH_ADD
| (TCG_REG_PC << 16) | (rt << 12)
| (20 << 7) | (diff >> 12));
/* ldr rd, [rt, #low] */
insn = deposit32(insn, 12, 4, rt);
diff &= 0xfff;
u = 1;
}
insn = deposit32(insn, 23, 1, u);
insn = deposit32(insn, 0, 12, diff);
*code_ptr = insn;
} else {
g_assert_not_reached();
}
}
#define TCG_CT_CONST_ARM 0x100
@ -581,9 +612,20 @@ static inline void tcg_out_ld8s_r(TCGContext *s, int cond, TCGReg rt,
tcg_out_memop_r(s, cond, INSN_LDRSB_REG, rt, rn, rm, 1, 1, 0);
}
static void tcg_out_movi_pool(TCGContext *s, int cond, int rd, uint32_t arg)
{
/* The 12-bit range on the ldr insn is sometimes a bit too small.
In order to get around that we require two insns, one of which
will usually be a nop, but may be replaced in patch_reloc. */
new_pool_label(s, arg, R_ARM_PC13, s->code_ptr, 0);
tcg_out_ld32_12(s, cond, rd, TCG_REG_PC, 0);
tcg_out_nop(s);
}
static void tcg_out_movi32(TCGContext *s, int cond, int rd, uint32_t arg)
{
int rot, opc, rn, diff;
int rot, diff, opc, sh1, sh2;
uint32_t tt0, tt1, tt2;
/* Check a single MOV/MVN before anything else. */
rot = encode_imm(arg);
@ -631,24 +673,30 @@ static void tcg_out_movi32(TCGContext *s, int cond, int rd, uint32_t arg)
return;
}
/* TODO: This is very suboptimal, we can easily have a constant
pool somewhere after all the instructions. */
/* Look for sequences of two insns. If we have lots of 1's, we can
shorten the sequence by beginning with mvn and then clearing
higher bits with eor. */
tt0 = arg;
opc = ARITH_MOV;
rn = 0;
/* If we have lots of leading 1's, we can shorten the sequence by
beginning with mvn and then clearing higher bits with eor. */
if (clz32(~arg) > clz32(arg)) {
opc = ARITH_MVN, arg = ~arg;
if (ctpop32(arg) > 16) {
tt0 = ~arg;
opc = ARITH_MVN;
}
sh1 = ctz32(tt0) & ~1;
tt1 = tt0 & ~(0xff << sh1);
sh2 = ctz32(tt1) & ~1;
tt2 = tt1 & ~(0xff << sh2);
if (tt2 == 0) {
rot = ((32 - sh1) << 7) & 0xf00;
tcg_out_dat_imm(s, cond, opc, rd, 0, ((tt0 >> sh1) & 0xff) | rot);
rot = ((32 - sh2) << 7) & 0xf00;
tcg_out_dat_imm(s, cond, ARITH_EOR, rd, rd,
((tt0 >> sh2) & 0xff) | rot);
return;
}
do {
int i = ctz32(arg) & ~1;
rot = ((32 - i) << 7) & 0xf00;
tcg_out_dat_imm(s, cond, opc, rd, rn, ((arg >> i) & 0xff) | rot);
arg &= ~(0xff << i);
opc = ARITH_EOR;
rn = rd;
} while (arg);
/* Otherwise, drop it into the constant pool. */
tcg_out_movi_pool(s, cond, rd, arg);
}
static inline void tcg_out_dat_rI(TCGContext *s, int cond, int opc, TCGArg dst,
@ -2164,6 +2212,14 @@ static inline void tcg_out_movi(TCGContext *s, TCGType type,
tcg_out_movi32(s, COND_AL, ret, arg);
}
static void tcg_out_nop_fill(tcg_insn_unit *p, int count)
{
int i;
for (i = 0; i < count; ++i) {
p[i] = INSN_NOP;
}
}
/* Compute frame size via macros, to share between tcg_target_qemu_prologue
and tcg_register_jit. */