* [PATCH 0/2] tcg: Eliminate scratch regs from i386 backend
@ 2020-12-11 1:14 Richard Henderson
2020-12-11 1:14 ` [PATCH 1/2] tcg/i386: Adjust TCG_TARGET_HAS_MEMORY_BSWAP Richard Henderson
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Richard Henderson @ 2020-12-11 1:14 UTC (permalink / raw)
To: qemu-devel
Eliminating these cleans up the backend a bit, allows the
code generator more freedom to properly place the inputs.
r~
Richard Henderson (2):
tcg/i386: Adjust TCG_TARGET_HAS_MEMORY_BSWAP
tcg: Introduce INDEX_op_qemu_st8_i32
include/tcg/tcg-opc.h | 5 ++
tcg/aarch64/tcg-target.h | 1 +
tcg/arm/tcg-target.h | 1 +
tcg/i386/tcg-target.h | 6 +-
tcg/mips/tcg-target.h | 1 +
tcg/ppc/tcg-target.h | 1 +
tcg/riscv/tcg-target.h | 1 +
tcg/s390/tcg-target.h | 1 +
tcg/sparc/tcg-target.h | 1 +
tcg/tci/tcg-target.h | 1 +
tcg/optimize.c | 1 +
tcg/tcg-op.c | 6 +-
tcg/tcg.c | 4 ++
tcg/README | 5 ++
tcg/i386/tcg-target.c.inc | 138 ++++++++++++++++----------------------
15 files changed, 91 insertions(+), 82 deletions(-)
--
2.25.1
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 1/2] tcg/i386: Adjust TCG_TARGET_HAS_MEMORY_BSWAP
2020-12-11 1:14 [PATCH 0/2] tcg: Eliminate scratch regs from i386 backend Richard Henderson
@ 2020-12-11 1:14 ` Richard Henderson
2021-01-05 13:42 ` Philippe Mathieu-Daudé
2020-12-11 1:14 ` [PATCH 2/2] tcg: Introduce INDEX_op_qemu_st8_i32 Richard Henderson
2021-01-05 0:04 ` [PATCH 0/2] tcg: Eliminate scratch regs from i386 backend Richard Henderson
2 siblings, 1 reply; 6+ messages in thread
From: Richard Henderson @ 2020-12-11 1:14 UTC (permalink / raw)
To: qemu-devel
Always true when movbe is available, otherwise leave
this to generic code.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
tcg/i386/tcg-target.h | 3 +-
tcg/i386/tcg-target.c.inc | 119 ++++++++++++++------------------------
2 files changed, 47 insertions(+), 75 deletions(-)
diff --git a/tcg/i386/tcg-target.h b/tcg/i386/tcg-target.h
index abd4ac7fc0..89700ab6af 100644
--- a/tcg/i386/tcg-target.h
+++ b/tcg/i386/tcg-target.h
@@ -101,6 +101,7 @@ extern bool have_bmi1;
extern bool have_popcnt;
extern bool have_avx1;
extern bool have_avx2;
+extern bool have_movbe;
/* optional instructions */
#define TCG_TARGET_HAS_div2_i32 1
@@ -229,7 +230,7 @@ static inline void tb_target_set_jmp_target(uintptr_t tc_ptr,
#define TCG_TARGET_DEFAULT_MO (TCG_MO_ALL & ~TCG_MO_ST_LD)
-#define TCG_TARGET_HAS_MEMORY_BSWAP 1
+#define TCG_TARGET_HAS_MEMORY_BSWAP have_movbe
#ifdef CONFIG_SOFTMMU
#define TCG_TARGET_NEED_LDST_LABELS
diff --git a/tcg/i386/tcg-target.c.inc b/tcg/i386/tcg-target.c.inc
index d8797ed398..01588cdcb4 100644
--- a/tcg/i386/tcg-target.c.inc
+++ b/tcg/i386/tcg-target.c.inc
@@ -154,13 +154,12 @@ bool have_bmi1;
bool have_popcnt;
bool have_avx1;
bool have_avx2;
+bool have_movbe;
#ifdef CONFIG_CPUID_H
-static bool have_movbe;
static bool have_bmi2;
static bool have_lzcnt;
#else
-# define have_movbe 0
# define have_bmi2 0
# define have_lzcnt 0
#endif
@@ -1986,13 +1985,14 @@ static void tcg_out_qemu_ld_direct(TCGContext *s, TCGReg datalo, TCGReg datahi,
TCGReg base, int index, intptr_t ofs,
int seg, bool is64, MemOp memop)
{
- const MemOp real_bswap = memop & MO_BSWAP;
- MemOp bswap = real_bswap;
+ bool use_movbe = false;
int rexw = is64 * P_REXW;
int movop = OPC_MOVL_GvEv;
- if (have_movbe && real_bswap) {
- bswap = 0;
+ /* Do big-endian loads with movbe. */
+ if (memop & MO_BSWAP) {
+ tcg_debug_assert(have_movbe);
+ use_movbe = true;
movop = OPC_MOVBE_GyMy;
}
@@ -2006,23 +2006,28 @@ static void tcg_out_qemu_ld_direct(TCGContext *s, TCGReg datalo, TCGReg datahi,
base, index, 0, ofs);
break;
case MO_UW:
- tcg_out_modrm_sib_offset(s, OPC_MOVZWL + seg, datalo,
- base, index, 0, ofs);
- if (real_bswap) {
- tcg_out_rolw_8(s, datalo);
- }
- break;
- case MO_SW:
- if (real_bswap) {
- if (have_movbe) {
+ if (use_movbe) {
+ /* There is no extending movbe; only low 16-bits are modified. */
+ if (datalo != base && datalo != index) {
+ /* XOR breaks dependency chains. */
+ tgen_arithr(s, ARITH_XOR, datalo, datalo);
tcg_out_modrm_sib_offset(s, OPC_MOVBE_GyMy + P_DATA16 + seg,
datalo, base, index, 0, ofs);
} else {
- tcg_out_modrm_sib_offset(s, OPC_MOVZWL + seg, datalo,
- base, index, 0, ofs);
- tcg_out_rolw_8(s, datalo);
+ tcg_out_modrm_sib_offset(s, OPC_MOVBE_GyMy + P_DATA16 + seg,
+ datalo, base, index, 0, ofs);
+ tcg_out_ext16u(s, datalo, datalo);
}
- tcg_out_modrm(s, OPC_MOVSWL + rexw, datalo, datalo);
+ } else {
+ tcg_out_modrm_sib_offset(s, OPC_MOVZWL + seg, datalo,
+ base, index, 0, ofs);
+ }
+ break;
+ case MO_SW:
+ if (use_movbe) {
+ tcg_out_modrm_sib_offset(s, OPC_MOVBE_GyMy + P_DATA16 + seg,
+ datalo, base, index, 0, ofs);
+ tcg_out_ext16s(s, datalo, datalo, rexw);
} else {
tcg_out_modrm_sib_offset(s, OPC_MOVSWL + rexw + seg,
datalo, base, index, 0, ofs);
@@ -2030,18 +2035,12 @@ static void tcg_out_qemu_ld_direct(TCGContext *s, TCGReg datalo, TCGReg datahi,
break;
case MO_UL:
tcg_out_modrm_sib_offset(s, movop + seg, datalo, base, index, 0, ofs);
- if (bswap) {
- tcg_out_bswap32(s, datalo);
- }
break;
#if TCG_TARGET_REG_BITS == 64
case MO_SL:
- if (real_bswap) {
- tcg_out_modrm_sib_offset(s, movop + seg, datalo,
+ if (use_movbe) {
+ tcg_out_modrm_sib_offset(s, OPC_MOVBE_GyMy + seg, datalo,
base, index, 0, ofs);
- if (bswap) {
- tcg_out_bswap32(s, datalo);
- }
tcg_out_ext32s(s, datalo, datalo);
} else {
tcg_out_modrm_sib_offset(s, OPC_MOVSLQ + seg, datalo,
@@ -2053,12 +2052,9 @@ static void tcg_out_qemu_ld_direct(TCGContext *s, TCGReg datalo, TCGReg datahi,
if (TCG_TARGET_REG_BITS == 64) {
tcg_out_modrm_sib_offset(s, movop + P_REXW + seg, datalo,
base, index, 0, ofs);
- if (bswap) {
- tcg_out_bswap64(s, datalo);
- }
} else {
- if (real_bswap) {
- int t = datalo;
+ if (use_movbe) {
+ TCGReg t = datalo;
datalo = datahi;
datahi = t;
}
@@ -2073,14 +2069,10 @@ static void tcg_out_qemu_ld_direct(TCGContext *s, TCGReg datalo, TCGReg datahi,
tcg_out_modrm_sib_offset(s, movop + seg, datalo,
base, index, 0, ofs);
}
- if (bswap) {
- tcg_out_bswap32(s, datalo);
- tcg_out_bswap32(s, datahi);
- }
}
break;
default:
- tcg_abort();
+ g_assert_not_reached();
}
}
@@ -2128,24 +2120,27 @@ static void tcg_out_qemu_st_direct(TCGContext *s, TCGReg datalo, TCGReg datahi,
TCGReg base, int index, intptr_t ofs,
int seg, MemOp memop)
{
- /* ??? Ideally we wouldn't need a scratch register. For user-only,
- we could perform the bswap twice to restore the original value
- instead of moving to the scratch. But as it is, the L constraint
- means that TCG_REG_L0 is definitely free here. */
const TCGReg scratch = TCG_REG_L0;
- const MemOp real_bswap = memop & MO_BSWAP;
- MemOp bswap = real_bswap;
+ bool use_movbe = false;
int movop = OPC_MOVL_EvGv;
- if (have_movbe && real_bswap) {
- bswap = 0;
+ /*
+ * Do big-endian stores with movbe or softmmu.
+ * User-only without movbe will have its swapping done generically.
+ */
+ if (memop & MO_BSWAP) {
+ tcg_debug_assert(have_movbe);
+ use_movbe = true;
movop = OPC_MOVBE_MyGy;
}
switch (memop & MO_SIZE) {
case MO_8:
- /* In 32-bit mode, 8-bit stores can only happen from [abcd]x.
- Use the scratch register if necessary. */
+ /*
+ * 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;
@@ -2154,43 +2149,19 @@ static void tcg_out_qemu_st_direct(TCGContext *s, TCGReg datalo, TCGReg datahi,
datalo, base, index, 0, ofs);
break;
case MO_16:
- if (bswap) {
- tcg_out_mov(s, TCG_TYPE_I32, scratch, datalo);
- tcg_out_rolw_8(s, scratch);
- datalo = scratch;
- }
tcg_out_modrm_sib_offset(s, movop + P_DATA16 + seg, datalo,
base, index, 0, ofs);
break;
case MO_32:
- if (bswap) {
- tcg_out_mov(s, TCG_TYPE_I32, scratch, datalo);
- tcg_out_bswap32(s, scratch);
- datalo = scratch;
- }
tcg_out_modrm_sib_offset(s, movop + seg, datalo, base, index, 0, ofs);
break;
case MO_64:
if (TCG_TARGET_REG_BITS == 64) {
- if (bswap) {
- tcg_out_mov(s, TCG_TYPE_I64, scratch, datalo);
- tcg_out_bswap64(s, scratch);
- datalo = scratch;
- }
tcg_out_modrm_sib_offset(s, movop + P_REXW + seg, datalo,
base, index, 0, ofs);
- } else if (bswap) {
- tcg_out_mov(s, TCG_TYPE_I32, scratch, datahi);
- tcg_out_bswap32(s, scratch);
- tcg_out_modrm_sib_offset(s, OPC_MOVL_EvGv + seg, scratch,
- base, index, 0, ofs);
- tcg_out_mov(s, TCG_TYPE_I32, scratch, datalo);
- tcg_out_bswap32(s, scratch);
- tcg_out_modrm_sib_offset(s, OPC_MOVL_EvGv + seg, scratch,
- base, index, 0, ofs + 4);
} else {
- if (real_bswap) {
- int t = datalo;
+ if (use_movbe) {
+ TCGReg t = datalo;
datalo = datahi;
datahi = t;
}
@@ -2201,7 +2172,7 @@ static void tcg_out_qemu_st_direct(TCGContext *s, TCGReg datalo, TCGReg datahi,
}
break;
default:
- tcg_abort();
+ g_assert_not_reached();
}
}
--
2.25.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/2] tcg: Introduce INDEX_op_qemu_st8_i32
2020-12-11 1:14 [PATCH 0/2] tcg: Eliminate scratch regs from i386 backend Richard Henderson
2020-12-11 1:14 ` [PATCH 1/2] tcg/i386: Adjust TCG_TARGET_HAS_MEMORY_BSWAP Richard Henderson
@ 2020-12-11 1:14 ` Richard Henderson
2021-01-05 13:46 ` Philippe Mathieu-Daudé
2021-01-05 0:04 ` [PATCH 0/2] tcg: Eliminate scratch regs from i386 backend Richard Henderson
2 siblings, 1 reply; 6+ messages in thread
From: Richard Henderson @ 2020-12-11 1:14 UTC (permalink / raw)
To: qemu-devel
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.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
include/tcg/tcg-opc.h | 5 +++++
tcg/aarch64/tcg-target.h | 1 +
tcg/arm/tcg-target.h | 1 +
tcg/i386/tcg-target.h | 3 +++
tcg/mips/tcg-target.h | 1 +
tcg/ppc/tcg-target.h | 1 +
tcg/riscv/tcg-target.h | 1 +
tcg/s390/tcg-target.h | 1 +
tcg/sparc/tcg-target.h | 1 +
tcg/tci/tcg-target.h | 1 +
tcg/optimize.c | 1 +
tcg/tcg-op.c | 6 +++++-
tcg/tcg.c | 4 ++++
tcg/README | 5 +++++
tcg/i386/tcg-target.c.inc | 29 ++++++++++++++++++-----------
15 files changed, 49 insertions(+), 12 deletions(-)
diff --git a/include/tcg/tcg-opc.h b/include/tcg/tcg-opc.h
index 67092e82c6..70a76646c4 100644
--- a/include/tcg/tcg-opc.h
+++ b/include/tcg/tcg-opc.h
@@ -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)
diff --git a/tcg/aarch64/tcg-target.h b/tcg/aarch64/tcg-target.h
index 663dd0b95e..d1159d80c6 100644
--- a/tcg/aarch64/tcg-target.h
+++ b/tcg/aarch64/tcg-target.h
@@ -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
diff --git a/tcg/arm/tcg-target.h b/tcg/arm/tcg-target.h
index 17e771374d..1e132afa75 100644
--- a/tcg/arm/tcg-target.h
+++ b/tcg/arm/tcg-target.h
@@ -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,
diff --git a/tcg/i386/tcg-target.h b/tcg/i386/tcg-target.h
index 89700ab6af..abe8636f0d 100644
--- a/tcg/i386/tcg-target.h
+++ b/tcg/i386/tcg-target.h
@@ -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. */
diff --git a/tcg/mips/tcg-target.h b/tcg/mips/tcg-target.h
index c6b091d849..b04c12d317 100644
--- a/tcg/mips/tcg-target.h
+++ b/tcg/mips/tcg-target.h
@@ -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
diff --git a/tcg/ppc/tcg-target.h b/tcg/ppc/tcg-target.h
index be10363956..7ff46b3d6d 100644
--- a/tcg/ppc/tcg-target.h
+++ b/tcg/ppc/tcg-target.h
@@ -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
diff --git a/tcg/riscv/tcg-target.h b/tcg/riscv/tcg-target.h
index 032439d806..ccda7b83c4 100644
--- a/tcg/riscv/tcg-target.h
+++ b/tcg/riscv/tcg-target.h
@@ -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
diff --git a/tcg/s390/tcg-target.h b/tcg/s390/tcg-target.h
index 63c8797bd3..7e7396caf2 100644
--- a/tcg/s390/tcg-target.h
+++ b/tcg/s390/tcg-target.h
@@ -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
diff --git a/tcg/sparc/tcg-target.h b/tcg/sparc/tcg-target.h
index 633841ebf2..f2989b3b45 100644
--- a/tcg/sparc/tcg-target.h
+++ b/tcg/sparc/tcg-target.h
@@ -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
diff --git a/tcg/tci/tcg-target.h b/tcg/tci/tcg-target.h
index 8c1c1d265d..7192d5319e 100644
--- a/tcg/tci/tcg-target.h
+++ b/tcg/tci/tcg-target.h
@@ -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
diff --git a/tcg/optimize.c b/tcg/optimize.c
index 220f4601d5..7f0eb6a9e7 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -1537,6 +1537,7 @@ 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. */
diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
index 4b8a473fad..af7ce91ffa 100644
--- a/tcg/tcg-op.c
+++ b/tcg/tcg-op.c
@@ -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) {
diff --git a/tcg/tcg.c b/tcg/tcg.c
index 43c6cf8f52..829d4296e0 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -1426,6 +1426,9 @@ 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;
@@ -2086,6 +2089,7 @@ 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:
{
diff --git a/tcg/README b/tcg/README
index 2f051e5c97..0cf9e2727c 100644
--- a/tcg/README
+++ b/tcg/README
@@ -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.
diff --git a/tcg/i386/tcg-target.c.inc b/tcg/i386/tcg-target.c.inc
index 01588cdcb4..f8e9a24e3b 100644
--- a/tcg/i386/tcg-target.c.inc
+++ b/tcg/i386/tcg-target.c.inc
@@ -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
--
2.25.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 0/2] tcg: Eliminate scratch regs from i386 backend
2020-12-11 1:14 [PATCH 0/2] tcg: Eliminate scratch regs from i386 backend Richard Henderson
2020-12-11 1:14 ` [PATCH 1/2] tcg/i386: Adjust TCG_TARGET_HAS_MEMORY_BSWAP Richard Henderson
2020-12-11 1:14 ` [PATCH 2/2] tcg: Introduce INDEX_op_qemu_st8_i32 Richard Henderson
@ 2021-01-05 0:04 ` Richard Henderson
2 siblings, 0 replies; 6+ messages in thread
From: Richard Henderson @ 2021-01-05 0:04 UTC (permalink / raw)
To: qemu-devel; +Cc: Alex Bennée, Philippe Mathieu-Daudé
Ping?
On 12/10/20 3:14 PM, Richard Henderson wrote:
> Eliminating these cleans up the backend a bit, allows the
> code generator more freedom to properly place the inputs.
>
>
> r~
>
>
> Richard Henderson (2):
> tcg/i386: Adjust TCG_TARGET_HAS_MEMORY_BSWAP
> tcg: Introduce INDEX_op_qemu_st8_i32
>
> include/tcg/tcg-opc.h | 5 ++
> tcg/aarch64/tcg-target.h | 1 +
> tcg/arm/tcg-target.h | 1 +
> tcg/i386/tcg-target.h | 6 +-
> tcg/mips/tcg-target.h | 1 +
> tcg/ppc/tcg-target.h | 1 +
> tcg/riscv/tcg-target.h | 1 +
> tcg/s390/tcg-target.h | 1 +
> tcg/sparc/tcg-target.h | 1 +
> tcg/tci/tcg-target.h | 1 +
> tcg/optimize.c | 1 +
> tcg/tcg-op.c | 6 +-
> tcg/tcg.c | 4 ++
> tcg/README | 5 ++
> tcg/i386/tcg-target.c.inc | 138 ++++++++++++++++----------------------
> 15 files changed, 91 insertions(+), 82 deletions(-)
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] tcg/i386: Adjust TCG_TARGET_HAS_MEMORY_BSWAP
2020-12-11 1:14 ` [PATCH 1/2] tcg/i386: Adjust TCG_TARGET_HAS_MEMORY_BSWAP Richard Henderson
@ 2021-01-05 13:42 ` Philippe Mathieu-Daudé
0 siblings, 0 replies; 6+ messages in thread
From: Philippe Mathieu-Daudé @ 2021-01-05 13:42 UTC (permalink / raw)
To: Richard Henderson, qemu-devel
On 12/11/20 2:14 AM, Richard Henderson wrote:
> Always true when movbe is available, otherwise leave
> this to generic code.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> tcg/i386/tcg-target.h | 3 +-
> tcg/i386/tcg-target.c.inc | 119 ++++++++++++++------------------------
> 2 files changed, 47 insertions(+), 75 deletions(-)
LGTM but I'd feel safer with some x86 developer reviewing it.
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 2/2] tcg: Introduce INDEX_op_qemu_st8_i32
2020-12-11 1:14 ` [PATCH 2/2] tcg: Introduce INDEX_op_qemu_st8_i32 Richard Henderson
@ 2021-01-05 13:46 ` Philippe Mathieu-Daudé
0 siblings, 0 replies; 6+ messages in thread
From: Philippe Mathieu-Daudé @ 2021-01-05 13:46 UTC (permalink / raw)
To: Richard Henderson, qemu-devel
On 12/11/20 2:14 AM, Richard Henderson wrote:
> 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.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> include/tcg/tcg-opc.h | 5 +++++
> tcg/aarch64/tcg-target.h | 1 +
> tcg/arm/tcg-target.h | 1 +
> tcg/i386/tcg-target.h | 3 +++
> tcg/mips/tcg-target.h | 1 +
> tcg/ppc/tcg-target.h | 1 +
> tcg/riscv/tcg-target.h | 1 +
> tcg/s390/tcg-target.h | 1 +
> tcg/sparc/tcg-target.h | 1 +
> tcg/tci/tcg-target.h | 1 +
> tcg/optimize.c | 1 +
> tcg/tcg-op.c | 6 +++++-
> tcg/tcg.c | 4 ++++
> tcg/README | 5 +++++
> tcg/i386/tcg-target.c.inc | 29 ++++++++++++++++++-----------
> 15 files changed, 49 insertions(+), 12 deletions(-)
...
> diff --git a/tcg/i386/tcg-target.c.inc b/tcg/i386/tcg-target.c.inc
> index 01588cdcb4..f8e9a24e3b 100644
> --- a/tcg/i386/tcg-target.c.inc
> +++ b/tcg/i386/tcg-target.c.inc
> @@ -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
>
Again, another review from a x86 developer welcomed.
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-01-05 13:48 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2020-12-11 1:14 [PATCH 0/2] tcg: Eliminate scratch regs from i386 backend Richard Henderson
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2021-01-05 13:42 ` Philippe Mathieu-Daudé
2020-12-11 1:14 ` [PATCH 2/2] tcg: Introduce INDEX_op_qemu_st8_i32 Richard Henderson
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2021-01-05 0:04 ` [PATCH 0/2] tcg: Eliminate scratch regs from i386 backend Richard Henderson
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