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tcg: Optimize qemu_ld/st by generating slow paths at the end of a block 

Add optimized TCG qemu_ld/st generation which locates the code of TLB miss
cases at the end of a block after generating the other IRs.
Currently, this optimization supports only i386 and x86_64 hosts.

Signed-off-by: Yeongkyoon Lee <yeongkyoon.lee@samsung.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This commit is contained in:
Yeongkyoon Lee 2012-10-31 16:04:25 +09:00 committed by Blue Swirl
parent fdbb84d133
commit b76f0d8c2e
3 changed files with 338 additions and 144 deletions
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440
tcg/i386/tcg-target.c
View File

@ -1002,6 +1002,17 @@ static const void *qemu_st_helpers[4] = {
helper_stq_mmu,
};
static void add_qemu_ldst_label(TCGContext *s,
int is_ld,
int opc,
int data_reg,
int data_reg2,
int addrlo_reg,
int addrhi_reg,
int mem_index,
uint8_t *raddr,
uint8_t **label_ptr);
/* Perform the TLB load and compare.
Inputs:
@ -1060,19 +1071,19 @@ static inline void tcg_out_tlb_load(TCGContext *s, int addrlo_idx,
tcg_out_mov(s, type, r1, addrlo);
/* jne label1 */
tcg_out8(s, OPC_JCC_short + JCC_JNE);
/* jne slow_path */
tcg_out_opc(s, OPC_JCC_long + JCC_JNE, 0, 0, 0);
label_ptr[0] = s->code_ptr;
s->code_ptr++;
s->code_ptr += 4;
if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) {
/* cmp 4(r0), addrhi */
tcg_out_modrm_offset(s, OPC_CMP_GvEv, args[addrlo_idx+1], r0, 4);
/* jne label1 */
tcg_out8(s, OPC_JCC_short + JCC_JNE);
/* jne slow_path */
tcg_out_opc(s, OPC_JCC_long + JCC_JNE, 0, 0, 0);
label_ptr[1] = s->code_ptr;
s->code_ptr++;
s->code_ptr += 4;
}
/* TLB Hit. */
@ -1193,10 +1204,7 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args,
int addrlo_idx;
#if defined(CONFIG_SOFTMMU)
int mem_index, s_bits;
#if TCG_TARGET_REG_BITS == 32
int stack_adjust;
#endif
uint8_t *label_ptr[3];
uint8_t *label_ptr[2];
#endif
data_reg = args[0];
@ -1216,87 +1224,17 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args,
/* TLB Hit. */
tcg_out_qemu_ld_direct(s, data_reg, data_reg2, TCG_REG_L1, 0, 0, opc);
/* jmp label2 */
tcg_out8(s, OPC_JMP_short);
label_ptr[2] = s->code_ptr;
s->code_ptr++;
/* TLB Miss. */
/* label1: */
*label_ptr[0] = s->code_ptr - label_ptr[0] - 1;
if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) {
*label_ptr[1] = s->code_ptr - label_ptr[1] - 1;
}
/* XXX: move that code at the end of the TB */
#if TCG_TARGET_REG_BITS == 32
tcg_out_pushi(s, mem_index);
stack_adjust = 4;
if (TARGET_LONG_BITS == 64) {
tcg_out_push(s, args[addrlo_idx + 1]);
stack_adjust += 4;
}
tcg_out_push(s, args[addrlo_idx]);
stack_adjust += 4;
tcg_out_push(s, TCG_AREG0);
stack_adjust += 4;
#else
tcg_out_mov(s, TCG_TYPE_I64, tcg_target_call_iarg_regs[0], TCG_AREG0);
/* The second argument is already loaded with addrlo. */
tcg_out_movi(s, TCG_TYPE_I32, tcg_target_call_iarg_regs[2], mem_index);
#endif
tcg_out_calli(s, (tcg_target_long)qemu_ld_helpers[s_bits]);
#if TCG_TARGET_REG_BITS == 32
if (stack_adjust == (TCG_TARGET_REG_BITS / 8)) {
/* Pop and discard. This is 2 bytes smaller than the add. */
tcg_out_pop(s, TCG_REG_ECX);
} else if (stack_adjust != 0) {
tcg_out_addi(s, TCG_REG_CALL_STACK, stack_adjust);
}
#endif
switch(opc) {
case 0 | 4:
tcg_out_ext8s(s, data_reg, TCG_REG_EAX, P_REXW);
break;
case 1 | 4:
tcg_out_ext16s(s, data_reg, TCG_REG_EAX, P_REXW);
break;
case 0:
tcg_out_ext8u(s, data_reg, TCG_REG_EAX);
break;
case 1:
tcg_out_ext16u(s, data_reg, TCG_REG_EAX);
break;
case 2:
tcg_out_mov(s, TCG_TYPE_I32, data_reg, TCG_REG_EAX);
break;
#if TCG_TARGET_REG_BITS == 64
case 2 | 4:
tcg_out_ext32s(s, data_reg, TCG_REG_EAX);
break;
#endif
case 3:
if (TCG_TARGET_REG_BITS == 64) {
tcg_out_mov(s, TCG_TYPE_I64, data_reg, TCG_REG_RAX);
} else if (data_reg == TCG_REG_EDX) {
/* xchg %edx, %eax */
tcg_out_opc(s, OPC_XCHG_ax_r32 + TCG_REG_EDX, 0, 0, 0);
tcg_out_mov(s, TCG_TYPE_I32, data_reg2, TCG_REG_EAX);
} else {
tcg_out_mov(s, TCG_TYPE_I32, data_reg, TCG_REG_EAX);
tcg_out_mov(s, TCG_TYPE_I32, data_reg2, TCG_REG_EDX);
}
break;
default:
tcg_abort();
}
/* label2: */
*label_ptr[2] = s->code_ptr - label_ptr[2] - 1;
/* Record the current context of a load into ldst label */
add_qemu_ldst_label(s,
1,
opc,
data_reg,
data_reg2,
args[addrlo_idx],
args[addrlo_idx + 1],
mem_index,
s->code_ptr,
label_ptr);
#else
{
int32_t offset = GUEST_BASE;
@ -1393,8 +1331,7 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args,
int addrlo_idx;
#if defined(CONFIG_SOFTMMU)
int mem_index, s_bits;
int stack_adjust;
uint8_t *label_ptr[3];
uint8_t *label_ptr[2];
#endif
data_reg = args[0];
@ -1414,57 +1351,17 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args,
/* TLB Hit. */
tcg_out_qemu_st_direct(s, data_reg, data_reg2, TCG_REG_L1, 0, 0, opc);
/* jmp label2 */
tcg_out8(s, OPC_JMP_short);
label_ptr[2] = s->code_ptr;
s->code_ptr++;
/* TLB Miss. */
/* label1: */
*label_ptr[0] = s->code_ptr - label_ptr[0] - 1;
if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) {
*label_ptr[1] = s->code_ptr - label_ptr[1] - 1;
}
/* XXX: move that code at the end of the TB */
#if TCG_TARGET_REG_BITS == 32
tcg_out_pushi(s, mem_index);
stack_adjust = 4;
if (opc == 3) {
tcg_out_push(s, data_reg2);
stack_adjust += 4;
}
tcg_out_push(s, data_reg);
stack_adjust += 4;
if (TARGET_LONG_BITS == 64) {
tcg_out_push(s, args[addrlo_idx + 1]);
stack_adjust += 4;
}
tcg_out_push(s, args[addrlo_idx]);
stack_adjust += 4;
tcg_out_push(s, TCG_AREG0);
stack_adjust += 4;
#else
tcg_out_mov(s, TCG_TYPE_I64, tcg_target_call_iarg_regs[0], TCG_AREG0);
/* The second argument is already loaded with addrlo. */
tcg_out_mov(s, (opc == 3 ? TCG_TYPE_I64 : TCG_TYPE_I32),
tcg_target_call_iarg_regs[2], data_reg);
tcg_out_movi(s, TCG_TYPE_I32, tcg_target_call_iarg_regs[3], mem_index);
stack_adjust = 0;
#endif
tcg_out_calli(s, (tcg_target_long)qemu_st_helpers[s_bits]);
if (stack_adjust == (TCG_TARGET_REG_BITS / 8)) {
/* Pop and discard. This is 2 bytes smaller than the add. */
tcg_out_pop(s, TCG_REG_ECX);
} else if (stack_adjust != 0) {
tcg_out_addi(s, TCG_REG_CALL_STACK, stack_adjust);
}
/* label2: */
*label_ptr[2] = s->code_ptr - label_ptr[2] - 1;
/* Record the current context of a store into ldst label */
add_qemu_ldst_label(s,
0,
opc,
data_reg,
data_reg2,
args[addrlo_idx],
args[addrlo_idx + 1],
mem_index,
s->code_ptr,
label_ptr);
#else
{
int32_t offset = GUEST_BASE;
@ -1491,6 +1388,261 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args,
#endif
}
#if defined(CONFIG_SOFTMMU)
/*
* Record the context of a call to the out of line helper code for the slow path
* for a load or store, so that we can later generate the correct helper code
*/
static void add_qemu_ldst_label(TCGContext *s,
int is_ld,
int opc,
int data_reg,
int data_reg2,
int addrlo_reg,
int addrhi_reg,
int mem_index,
uint8_t *raddr,
uint8_t **label_ptr)
{
int idx;
TCGLabelQemuLdst *label;
if (s->nb_qemu_ldst_labels >= TCG_MAX_QEMU_LDST) {
tcg_abort();
}
idx = s->nb_qemu_ldst_labels++;
label = (TCGLabelQemuLdst *)&s->qemu_ldst_labels[idx];
label->is_ld = is_ld;
label->opc = opc;
label->datalo_reg = data_reg;
label->datahi_reg = data_reg2;
label->addrlo_reg = addrlo_reg;
label->addrhi_reg = addrhi_reg;
label->mem_index = mem_index;
label->raddr = raddr;
label->label_ptr[0] = label_ptr[0];
if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) {
label->label_ptr[1] = label_ptr[1];
}
}
/*
* Generate code for the slow path for a load at the end of block
*/
static void tcg_out_qemu_ld_slow_path(TCGContext *s, TCGLabelQemuLdst *label)
{
int s_bits;
int opc = label->opc;
int mem_index = label->mem_index;
#if TCG_TARGET_REG_BITS == 32
int stack_adjust;
int addrlo_reg = label->addrlo_reg;
int addrhi_reg = label->addrhi_reg;
#endif
int data_reg = label->datalo_reg;
int data_reg2 = label->datahi_reg;
uint8_t *raddr = label->raddr;
uint8_t **label_ptr = &label->label_ptr[0];
s_bits = opc & 3;
/* resolve label address */
*(uint32_t *)label_ptr[0] = (uint32_t)(s->code_ptr - label_ptr[0] - 4);
if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) {
*(uint32_t *)label_ptr[1] = (uint32_t)(s->code_ptr - label_ptr[1] - 4);
}
#if TCG_TARGET_REG_BITS == 32
tcg_out_pushi(s, mem_index);
stack_adjust = 4;
if (TARGET_LONG_BITS == 64) {
tcg_out_push(s, addrhi_reg);
stack_adjust += 4;
}
tcg_out_push(s, addrlo_reg);
stack_adjust += 4;
tcg_out_push(s, TCG_AREG0);
stack_adjust += 4;
#else
tcg_out_mov(s, TCG_TYPE_I64, tcg_target_call_iarg_regs[0], TCG_AREG0);
/* The second argument is already loaded with addrlo. */
tcg_out_movi(s, TCG_TYPE_I32, tcg_target_call_iarg_regs[2], mem_index);
#endif
/* Code generation of qemu_ld/st's slow path calling MMU helper
PRE_PROC ...
call MMU helper
jmp POST_PROC (2b) : short forward jump <- GETRA()
jmp next_code (5b) : dummy long backward jump which is never executed
POST_PROC ... : do post-processing <- GETRA() + 7
jmp next_code : jump to the code corresponding to next IR of qemu_ld/st
*/
tcg_out_calli(s, (tcg_target_long)qemu_ld_helpers[s_bits]);
/* Jump to post-processing code */
tcg_out8(s, OPC_JMP_short);
tcg_out8(s, 5);
/* Dummy backward jump having information of fast path'pc for MMU helpers */
tcg_out8(s, OPC_JMP_long);
*(int32_t *)s->code_ptr = (int32_t)(raddr - s->code_ptr - 4);
s->code_ptr += 4;
#if TCG_TARGET_REG_BITS == 32
if (stack_adjust == (TCG_TARGET_REG_BITS / 8)) {
/* Pop and discard. This is 2 bytes smaller than the add. */
tcg_out_pop(s, TCG_REG_ECX);
} else if (stack_adjust != 0) {
tcg_out_addi(s, TCG_REG_CALL_STACK, stack_adjust);
}
#endif
switch(opc) {
case 0 | 4:
tcg_out_ext8s(s, data_reg, TCG_REG_EAX, P_REXW);
break;
case 1 | 4:
tcg_out_ext16s(s, data_reg, TCG_REG_EAX, P_REXW);
break;
case 0:
tcg_out_ext8u(s, data_reg, TCG_REG_EAX);
break;
case 1:
tcg_out_ext16u(s, data_reg, TCG_REG_EAX);
break;
case 2:
tcg_out_mov(s, TCG_TYPE_I32, data_reg, TCG_REG_EAX);
break;
#if TCG_TARGET_REG_BITS == 64
case 2 | 4:
tcg_out_ext32s(s, data_reg, TCG_REG_EAX);
break;
#endif
case 3:
if (TCG_TARGET_REG_BITS == 64) {
tcg_out_mov(s, TCG_TYPE_I64, data_reg, TCG_REG_RAX);
} else if (data_reg == TCG_REG_EDX) {
/* xchg %edx, %eax */
tcg_out_opc(s, OPC_XCHG_ax_r32 + TCG_REG_EDX, 0, 0, 0);
tcg_out_mov(s, TCG_TYPE_I32, data_reg2, TCG_REG_EAX);
} else {
tcg_out_mov(s, TCG_TYPE_I32, data_reg, TCG_REG_EAX);
tcg_out_mov(s, TCG_TYPE_I32, data_reg2, TCG_REG_EDX);
}
break;
default:
tcg_abort();
}
/* Jump to the code corresponding to next IR of qemu_st */
tcg_out_jmp(s, (tcg_target_long)raddr);
}
/*
* Generate code for the slow path for a store at the end of block
*/
static void tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *label)
{
int s_bits;
int stack_adjust;
int opc = label->opc;
int mem_index = label->mem_index;
int data_reg = label->datalo_reg;
#if TCG_TARGET_REG_BITS == 32
int data_reg2 = label->datahi_reg;
int addrlo_reg = label->addrlo_reg;
int addrhi_reg = label->addrhi_reg;
#endif
uint8_t *raddr = label->raddr;
uint8_t **label_ptr = &label->label_ptr[0];
s_bits = opc & 3;
/* resolve label address */
*(uint32_t *)label_ptr[0] = (uint32_t)(s->code_ptr - label_ptr[0] - 4);
if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) {
*(uint32_t *)label_ptr[1] = (uint32_t)(s->code_ptr - label_ptr[1] - 4);
}
#if TCG_TARGET_REG_BITS == 32
tcg_out_pushi(s, mem_index);
stack_adjust = 4;
if (opc == 3) {
tcg_out_push(s, data_reg2);
stack_adjust += 4;
}
tcg_out_push(s, data_reg);
stack_adjust += 4;
if (TARGET_LONG_BITS == 64) {
tcg_out_push(s, addrhi_reg);
stack_adjust += 4;
}
tcg_out_push(s, addrlo_reg);
stack_adjust += 4;
tcg_out_push(s, TCG_AREG0);
stack_adjust += 4;
#else
tcg_out_mov(s, TCG_TYPE_I64, tcg_target_call_iarg_regs[0], TCG_AREG0);
/* The second argument is already loaded with addrlo. */
tcg_out_mov(s, (opc == 3 ? TCG_TYPE_I64 : TCG_TYPE_I32),
tcg_target_call_iarg_regs[2], data_reg);
tcg_out_movi(s, TCG_TYPE_I32, tcg_target_call_iarg_regs[3], mem_index);
stack_adjust = 0;
#endif
/* Code generation of qemu_ld/st's slow path calling MMU helper
PRE_PROC ...
call MMU helper
jmp POST_PROC (2b) : short forward jump <- GETRA()
jmp next_code (5b) : dummy long backward jump which is never executed
POST_PROC ... : do post-processing <- GETRA() + 7
jmp next_code : jump to the code corresponding to next IR of qemu_ld/st
*/
tcg_out_calli(s, (tcg_target_long)qemu_st_helpers[s_bits]);
/* Jump to post-processing code */
tcg_out8(s, OPC_JMP_short);
tcg_out8(s, 5);
/* Dummy backward jump having information of fast path'pc for MMU helpers */
tcg_out8(s, OPC_JMP_long);
*(int32_t *)s->code_ptr = (int32_t)(raddr - s->code_ptr - 4);
s->code_ptr += 4;
if (stack_adjust == (TCG_TARGET_REG_BITS / 8)) {
/* Pop and discard. This is 2 bytes smaller than the add. */
tcg_out_pop(s, TCG_REG_ECX);
} else if (stack_adjust != 0) {
tcg_out_addi(s, TCG_REG_CALL_STACK, stack_adjust);
}
/* Jump to the code corresponding to next IR of qemu_st */
tcg_out_jmp(s, (tcg_target_long)raddr);
}
/*
* Generate TB finalization at the end of block
*/
void tcg_out_tb_finalize(TCGContext *s)
{
int i;
TCGLabelQemuLdst *label;
/* qemu_ld/st slow paths */
for (i = 0; i < s->nb_qemu_ldst_labels; i++) {
label = (TCGLabelQemuLdst *)&s->qemu_ldst_labels[i];
if (label->is_ld) {
tcg_out_qemu_ld_slow_path(s, label);
} else {
tcg_out_qemu_st_slow_path(s, label);
}
}
}
#endif /* CONFIG_SOFTMMU */
static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
const TCGArg *args, const int *const_args)
{

12
tcg/tcg.c
View File

@ -299,6 +299,14 @@ void tcg_func_start(TCGContext *s)
gen_opc_ptr = gen_opc_buf;
gen_opparam_ptr = gen_opparam_buf;
#if defined(CONFIG_QEMU_LDST_OPTIMIZATION) && defined(CONFIG_SOFTMMU)
/* Initialize qemu_ld/st labels to assist code generation at the end of TB
for TLB miss cases at the end of TB */
s->qemu_ldst_labels = tcg_malloc(sizeof(TCGLabelQemuLdst) *
TCG_MAX_QEMU_LDST);
s->nb_qemu_ldst_labels = 0;
#endif
}
static inline void tcg_temp_alloc(TCGContext *s, int n)
@ -2314,6 +2322,10 @@ static inline int tcg_gen_code_common(TCGContext *s, uint8_t *gen_code_buf,
#endif
}
the_end:
#if defined(CONFIG_QEMU_LDST_OPTIMIZATION) && defined(CONFIG_SOFTMMU)
/* Generate TB finalization at the end of block */
tcg_out_tb_finalize(s);
#endif
return -1;
}

30
tcg/tcg.h
View File

@ -188,6 +188,24 @@ typedef tcg_target_ulong TCGArg;
are aliases for target_ulong and host pointer sized values respectively.
*/
#if defined(CONFIG_QEMU_LDST_OPTIMIZATION) && defined(CONFIG_SOFTMMU)
/* Macros/structures for qemu_ld/st IR code optimization:
TCG_MAX_HELPER_LABELS is defined as same as OPC_BUF_SIZE in exec-all.h. */
#define TCG_MAX_QEMU_LDST 640
typedef struct TCGLabelQemuLdst {
int is_ld:1; /* qemu_ld: 1, qemu_st: 0 */
int opc:4;
int addrlo_reg; /* reg index for low word of guest virtual addr */
int addrhi_reg; /* reg index for high word of guest virtual addr */
int datalo_reg; /* reg index for low word to be loaded or stored */
int datahi_reg; /* reg index for high word to be loaded or stored */
int mem_index; /* soft MMU memory index */
uint8_t *raddr; /* gen code addr of the next IR of qemu_ld/st IR */
uint8_t *label_ptr[2]; /* label pointers to be updated */
} TCGLabelQemuLdst;
#endif
#ifdef CONFIG_DEBUG_TCG
#define DEBUG_TCGV 1
#endif
@ -431,6 +449,13 @@ struct TCGContext {
int temps_in_use;
int goto_tb_issue_mask;
#endif
#if defined(CONFIG_QEMU_LDST_OPTIMIZATION) && defined(CONFIG_SOFTMMU)
/* labels info for qemu_ld/st IRs
The labels help to generate TLB miss case codes at the end of TB */
TCGLabelQemuLdst *qemu_ldst_labels;
int nb_qemu_ldst_labels;
#endif
};
extern TCGContext tcg_ctx;
@ -634,3 +659,8 @@ extern uint8_t *code_gen_prologue;
#endif
void tcg_register_jit(void *buf, size_t buf_size);
#if defined(CONFIG_QEMU_LDST_OPTIMIZATION) && defined(CONFIG_SOFTMMU)
/* Generate TB finalization at the end of block */
void tcg_out_tb_finalize(TCGContext *s);
#endif