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tcg: Introduce INDEX_op_qemu_st8_i32

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Enable this on i386 to restrict the set of input registers
for an 8-bit store, as required by the architecture.  This
removes the last use of scratch registers for user-only mode.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2020-12-09 13:58:39 -06:00
parent d2ef1b83a7
commit 07ce0b0530
15 changed files with 49 additions and 12 deletions
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5
include/tcg/tcg-opc.h
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@ -211,6 +211,11 @@ DEF(qemu_ld_i64, DATA64_ARGS, TLADDR_ARGS, 1,
DEF(qemu_st_i64, 0, TLADDR_ARGS + DATA64_ARGS, 1,
TCG_OPF_CALL_CLOBBER | TCG_OPF_SIDE_EFFECTS | TCG_OPF_64BIT)
/* Only used by i386 to cope with stupid register constraints. */
DEF(qemu_st8_i32, 0, TLADDR_ARGS + 1, 1,
TCG_OPF_CALL_CLOBBER | TCG_OPF_SIDE_EFFECTS |
IMPL(TCG_TARGET_HAS_qemu_st8_i32))
/* Host vector support. */
#define IMPLVEC TCG_OPF_VECTOR | IMPL(TCG_TARGET_MAYBE_vec)

5
tcg/README
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@ -502,6 +502,7 @@ goto_ptr opcode, emitting this op is equivalent to emitting exit_tb(0).
* qemu_ld_i32/i64 t0, t1, flags, memidx
* qemu_st_i32/i64 t0, t1, flags, memidx
* qemu_st8_i32 t0, t1, flags, memidx
Load data at the guest address t1 into t0, or store data in t0 at guest
address t1. The _i32/_i64 size applies to the size of the input/output
@ -518,6 +519,10 @@ of the memory access.
For a 32-bit host, qemu_ld/st_i64 is guaranteed to only be used with a
64-bit memory access specified in flags.
For i386, qemu_st8_i32 is exactly like qemu_st_i32, except the size of
the memory operation is known to be 8-bit. This allows the backend to
provide a different set of register constraints.
********* Host vector operations
All of the vector ops have two parameters, TCGOP_VECL & TCGOP_VECE.

1
tcg/aarch64/tcg-target.h
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@ -88,6 +88,7 @@ typedef enum {
#define TCG_TARGET_HAS_extrl_i64_i32 0
#define TCG_TARGET_HAS_extrh_i64_i32 0
#define TCG_TARGET_HAS_goto_ptr 1
#define TCG_TARGET_HAS_qemu_st8_i32 0
#define TCG_TARGET_HAS_div_i64 1
#define TCG_TARGET_HAS_rem_i64 1

1
tcg/arm/tcg-target.h
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@ -126,6 +126,7 @@ extern bool use_idiv_instructions;
#define TCG_TARGET_HAS_rem_i32 0
#define TCG_TARGET_HAS_goto_ptr 1
#define TCG_TARGET_HAS_direct_jump 0
#define TCG_TARGET_HAS_qemu_st8_i32 0
enum {
TCG_AREG0 = TCG_REG_R6,

29
tcg/i386/tcg-target.c.inc
View File

@ -245,11 +245,21 @@ static const char *target_parse_constraint(TCGArgConstraint *ct,
ct->regs |= ALL_VECTOR_REGS;
break;
/* qemu_ld/st address constraint */
case 'L':
/* qemu_ld/st data+address constraint */
ct->regs = TCG_TARGET_REG_BITS == 64 ? 0xffff : 0xff;
#ifdef CONFIG_SOFTMMU
tcg_regset_reset_reg(ct->regs, TCG_REG_L0);
tcg_regset_reset_reg(ct->regs, TCG_REG_L1);
#endif
break;
case 's':
/* qemu_st8_i32 data constraint */
ct->regs = 0xf;
#ifdef CONFIG_SOFTMMU
tcg_regset_reset_reg(ct->regs, TCG_REG_L0);
tcg_regset_reset_reg(ct->regs, TCG_REG_L1);
#endif
break;
case 'e':
@ -2120,7 +2130,6 @@ static void tcg_out_qemu_st_direct(TCGContext *s, TCGReg datalo, TCGReg datahi,
TCGReg base, int index, intptr_t ofs,
int seg, MemOp memop)
{
const TCGReg scratch = TCG_REG_L0;
bool use_movbe = false;
int movop = OPC_MOVL_EvGv;
@ -2136,15 +2145,8 @@ static void tcg_out_qemu_st_direct(TCGContext *s, TCGReg datalo, TCGReg datahi,
switch (memop & MO_SIZE) {
case MO_8:
/*
* In 32-bit mode, 8-bit stores can only happen from [abcd]x.
* TODO: Adjust constraints such that this is is forced,
* then we won't need a scratch at all for user-only.
*/
if (TCG_TARGET_REG_BITS == 32 && datalo >= 4) {
tcg_out_mov(s, TCG_TYPE_I32, scratch, datalo);
datalo = scratch;
}
/* This is handled with constraints on INDEX_op_qemu_st8_i32. */
tcg_debug_assert(TCG_TARGET_REG_BITS == 64 || datalo < 4);
tcg_out_modrm_sib_offset(s, OPC_MOVB_EvGv + P_REXB_R + seg,
datalo, base, index, 0, ofs);
break;
@ -2491,6 +2493,7 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
tcg_out_qemu_ld(s, args, 1);
break;
case INDEX_op_qemu_st_i32:
case INDEX_op_qemu_st8_i32:
tcg_out_qemu_st(s, args, 0);
break;
case INDEX_op_qemu_st_i64:
@ -2949,9 +2952,11 @@ static const TCGTargetOpDef *tcg_target_op_def(TCGOpcode op)
static const TCGTargetOpDef r_0_ci = { .args_ct_str = { "r", "0", "ci" } };
static const TCGTargetOpDef r_L = { .args_ct_str = { "r", "L" } };
static const TCGTargetOpDef L_L = { .args_ct_str = { "L", "L" } };
static const TCGTargetOpDef s_L = { .args_ct_str = { "s", "L" } };
static const TCGTargetOpDef r_L_L = { .args_ct_str = { "r", "L", "L" } };
static const TCGTargetOpDef r_r_L = { .args_ct_str = { "r", "r", "L" } };
static const TCGTargetOpDef L_L_L = { .args_ct_str = { "L", "L", "L" } };
static const TCGTargetOpDef s_L_L = { .args_ct_str = { "s", "L", "L" } };
static const TCGTargetOpDef r_r_L_L
= { .args_ct_str = { "r", "r", "L", "L" } };
static const TCGTargetOpDef L_L_L_L
@ -3145,6 +3150,8 @@ static const TCGTargetOpDef *tcg_target_op_def(TCGOpcode op)
return TARGET_LONG_BITS <= TCG_TARGET_REG_BITS ? &r_L : &r_L_L;
case INDEX_op_qemu_st_i32:
return TARGET_LONG_BITS <= TCG_TARGET_REG_BITS ? &L_L : &L_L_L;
case INDEX_op_qemu_st8_i32:
return TARGET_LONG_BITS <= TCG_TARGET_REG_BITS ? &s_L : &s_L_L;
case INDEX_op_qemu_ld_i64:
return (TCG_TARGET_REG_BITS == 64 ? &r_L
: TARGET_LONG_BITS <= TCG_TARGET_REG_BITS ? &r_r_L

3
tcg/i386/tcg-target.h
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@ -172,6 +172,9 @@ extern bool have_movbe;
#define TCG_TARGET_HAS_muls2_i64 1
#define TCG_TARGET_HAS_muluh_i64 0
#define TCG_TARGET_HAS_mulsh_i64 0
#define TCG_TARGET_HAS_qemu_st8_i32 0
#else
#define TCG_TARGET_HAS_qemu_st8_i32 1
#endif
/* We do not support older SSE systems, only beginning with AVX1. */

1
tcg/mips/tcg-target.h
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@ -169,6 +169,7 @@ extern bool use_mips32r2_instructions;
#define TCG_TARGET_HAS_clz_i32 use_mips32r2_instructions
#define TCG_TARGET_HAS_ctz_i32 0
#define TCG_TARGET_HAS_ctpop_i32 0
#define TCG_TARGET_HAS_qemu_st8_i32 0
#if TCG_TARGET_REG_BITS == 64
#define TCG_TARGET_HAS_movcond_i64 use_movnz_instructions

1
tcg/optimize.c
View File

@ -1541,6 +1541,7 @@ void tcg_optimize(TCGContext *s)
case INDEX_op_qemu_ld_i32:
case INDEX_op_qemu_ld_i64:
case INDEX_op_qemu_st_i32:
case INDEX_op_qemu_st8_i32:
case INDEX_op_qemu_st_i64:
case INDEX_op_call:
/* Opcodes that touch guest memory stop the optimization. */

1
tcg/ppc/tcg-target.h
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@ -108,6 +108,7 @@ extern bool have_vsx;
#define TCG_TARGET_HAS_mulsh_i32 1
#define TCG_TARGET_HAS_goto_ptr 1
#define TCG_TARGET_HAS_direct_jump 1
#define TCG_TARGET_HAS_qemu_st8_i32 0
#if TCG_TARGET_REG_BITS == 64
#define TCG_TARGET_HAS_add2_i32 0

1
tcg/riscv/tcg-target.h
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@ -119,6 +119,7 @@ typedef enum {
#define TCG_TARGET_HAS_direct_jump 0
#define TCG_TARGET_HAS_brcond2 1
#define TCG_TARGET_HAS_setcond2 1
#define TCG_TARGET_HAS_qemu_st8_i32 0
#if TCG_TARGET_REG_BITS == 64
#define TCG_TARGET_HAS_movcond_i64 0

1
tcg/s390/tcg-target.h
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@ -97,6 +97,7 @@ extern uint64_t s390_facilities;
#define TCG_TARGET_HAS_extrh_i64_i32 0
#define TCG_TARGET_HAS_goto_ptr 1
#define TCG_TARGET_HAS_direct_jump (s390_facilities & FACILITY_GEN_INST_EXT)
#define TCG_TARGET_HAS_qemu_st8_i32 0
#define TCG_TARGET_HAS_div2_i64 1
#define TCG_TARGET_HAS_rot_i64 1

1
tcg/sparc/tcg-target.h
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@ -126,6 +126,7 @@ extern bool use_vis3_instructions;
#define TCG_TARGET_HAS_mulsh_i32 0
#define TCG_TARGET_HAS_goto_ptr 1
#define TCG_TARGET_HAS_direct_jump 1
#define TCG_TARGET_HAS_qemu_st8_i32 0
#define TCG_TARGET_HAS_extrl_i64_i32 1
#define TCG_TARGET_HAS_extrh_i64_i32 1

6
tcg/tcg-op.c
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@ -2883,7 +2883,11 @@ void tcg_gen_qemu_st_i32(TCGv_i32 val, TCGv addr, TCGArg idx, MemOp memop)
}
addr = plugin_prep_mem_callbacks(addr);
gen_ldst_i32(INDEX_op_qemu_st_i32, val, addr, memop, idx);
if (TCG_TARGET_HAS_qemu_st8_i32 && (memop & MO_SIZE) == MO_8) {
gen_ldst_i32(INDEX_op_qemu_st8_i32, val, addr, memop, idx);
} else {
gen_ldst_i32(INDEX_op_qemu_st_i32, val, addr, memop, idx);
}
plugin_gen_mem_callbacks(addr, info);
if (swap) {

4
tcg/tcg.c
View File

@ -1427,6 +1427,9 @@ bool tcg_op_supported(TCGOpcode op)
case INDEX_op_qemu_st_i64:
return true;
case INDEX_op_qemu_st8_i32:
return TCG_TARGET_HAS_qemu_st8_i32;
case INDEX_op_goto_ptr:
return TCG_TARGET_HAS_goto_ptr;
@ -2087,6 +2090,7 @@ static void tcg_dump_ops(TCGContext *s, bool have_prefs)
break;
case INDEX_op_qemu_ld_i32:
case INDEX_op_qemu_st_i32:
case INDEX_op_qemu_st8_i32:
case INDEX_op_qemu_ld_i64:
case INDEX_op_qemu_st_i64:
{

1
tcg/tci/tcg-target.h
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@ -88,6 +88,7 @@
#define TCG_TARGET_HAS_mulsh_i32 0
#define TCG_TARGET_HAS_goto_ptr 0
#define TCG_TARGET_HAS_direct_jump 1
#define TCG_TARGET_HAS_qemu_st8_i32 0
#if TCG_TARGET_REG_BITS == 64
#define TCG_TARGET_HAS_extrl_i64_i32 0