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authorRichard Henderson <rth@twiddle.net>2013-07-25 07:16:52 -1000
committerRichard Henderson <rth@twiddle.net>2013-08-26 13:31:54 -0700
commit401c227b0a1134245ec61c6c5a9997cfc963c8e4 (patch)
tree753453aebeb53f96d70405928289994b2f2a5f07
parentaac1fb0576e5bea72681e91c38caffc17741eb80 (diff)
tcg-i386: Use new return-argument ld/st helpers
Discontinue the jump-around-jump-to-jump scheme, trading it for a single immediate move instruction. The two extra jumps always consume 7 bytes, whereas the immediate move is either 5 or 7 bytes depending on where the code_gen_buffer gets located. Signed-off-by: Richard Henderson <rth@twiddle.net>
-rw-r--r--include/exec/exec-all.h13
-rw-r--r--tcg/i386/tcg-target.c103
2 files changed, 49 insertions, 67 deletions
diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index 5920f73c90..b70028a0eb 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -326,18 +326,9 @@ extern uintptr_t tci_tb_ptr;
(6) jump to corresponding code of the next of fast path
*/
# if defined(__i386__) || defined(__x86_64__)
-/* To avoid broken disassembling, long jmp is used for embedding fast path pc,
- so that the destination is the next code of fast path, though this jmp is
- never executed.
-
- call MMU helper
- jmp POST_PROC (2byte) <- GETRA()
- jmp NEXT_CODE (5byte)
- POST_PROCESS ... <- GETRA() + 7
- */
# define GETRA() ((uintptr_t)__builtin_return_address(0))
-# define GETPC_LDST() ((uintptr_t)(GETRA() + 7 + \
- *(int32_t *)((void *)GETRA() + 3) - 1))
+/* The return address argument for ldst is passed directly. */
+# define GETPC_LDST() (abort(), 0)
# elif defined (_ARCH_PPC) && !defined (_ARCH_PPC64)
# define GETRA() ((uintptr_t)__builtin_return_address(0))
# define GETPC_LDST() ((uintptr_t) ((*(int32_t *)(GETRA() - 4)) - 1))
diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c
index fba50f86e8..12a7ca3440 100644
--- a/tcg/i386/tcg-target.c
+++ b/tcg/i386/tcg-target.c
@@ -190,11 +190,11 @@ static int target_parse_constraint(TCGArgConstraint *ct, const char **pct_str)
/* qemu_ld/st address constraint */
case 'L':
ct->ct |= TCG_CT_REG;
-#if TCG_TARGET_REG_BITS == 64
+ if (TCG_TARGET_REG_BITS == 64) {
tcg_regset_set32(ct->u.regs, 0, 0xffff);
-#else
+ } else {
tcg_regset_set32(ct->u.regs, 0, 0xff);
-#endif
+ }
tcg_regset_reset_reg(ct->u.regs, TCG_REG_L0);
tcg_regset_reset_reg(ct->u.regs, TCG_REG_L1);
break;
@@ -1025,22 +1025,24 @@ static void tcg_out_jmp(TCGContext *s, tcg_target_long dest)
#include "exec/softmmu_defs.h"
-/* helper signature: helper_ld_mmu(CPUState *env, target_ulong addr,
- int mmu_idx) */
-static const void *qemu_ld_helpers[4] = {
- helper_ldb_mmu,
- helper_ldw_mmu,
- helper_ldl_mmu,
- helper_ldq_mmu,
+/* helper signature: helper_ret_ld_mmu(CPUState *env, target_ulong addr,
+ * int mmu_idx, uintptr_t ra)
+ */
+static const void * const qemu_ld_helpers[4] = {
+ helper_ret_ldb_mmu,
+ helper_ret_ldw_mmu,
+ helper_ret_ldl_mmu,
+ helper_ret_ldq_mmu,
};
-/* helper signature: helper_st_mmu(CPUState *env, target_ulong addr,
- uintxx_t val, int mmu_idx) */
-static const void *qemu_st_helpers[4] = {
- helper_stb_mmu,
- helper_stw_mmu,
- helper_stl_mmu,
- helper_stq_mmu,
+/* helper signature: helper_ret_st_mmu(CPUState *env, target_ulong addr,
+ * uintxx_t val, int mmu_idx, uintptr_t ra)
+ */
+static const void * const qemu_st_helpers[4] = {
+ helper_ret_stb_mmu,
+ helper_ret_stw_mmu,
+ helper_ret_stl_mmu,
+ helper_ret_stq_mmu,
};
static void add_qemu_ldst_label(TCGContext *s,
@@ -1468,6 +1470,12 @@ static void add_qemu_ldst_label(TCGContext *s,
}
}
+/* See the GETPC definition in include/exec/exec-all.h. */
+static inline uintptr_t do_getpc(uint8_t *raddr)
+{
+ return (uintptr_t)raddr - 1;
+}
+
/*
* Generate code for the slow path for a load at the end of block
*/
@@ -1499,33 +1507,20 @@ static void tcg_out_qemu_ld_slow_path(TCGContext *s, TCGLabelQemuLdst *l)
}
tcg_out_sti(s, TCG_TYPE_I32, TCG_REG_ESP, ofs, l->mem_index);
+ ofs += 4;
+
+ tcg_out_sti(s, TCG_TYPE_I32, TCG_REG_ESP, ofs, do_getpc(l->raddr));
} else {
- tcg_out_mov(s, TCG_TYPE_I64, tcg_target_call_iarg_regs[0], TCG_AREG0);
+ tcg_out_mov(s, TCG_TYPE_PTR, 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],
l->mem_index);
+ tcg_out_movi(s, TCG_TYPE_PTR, tcg_target_call_iarg_regs[3],
+ do_getpc(l->raddr));
}
- /* 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)(l->raddr - s->code_ptr - 4);
- s->code_ptr += 4;
-
data_reg = l->datalo_reg;
switch(opc) {
case 0 | 4:
@@ -1606,36 +1601,32 @@ static void tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *l)
}
tcg_out_sti(s, TCG_TYPE_I32, TCG_REG_ESP, ofs, l->mem_index);
+ ofs += 4;
+
+ tcg_out_sti(s, TCG_TYPE_I32, TCG_REG_ESP, ofs, do_getpc(l->raddr));
} else {
- tcg_out_mov(s, TCG_TYPE_I64, tcg_target_call_iarg_regs[0], TCG_AREG0);
+ uintptr_t pc;
+
+ tcg_out_mov(s, TCG_TYPE_PTR, 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], l->datalo_reg);
tcg_out_movi(s, TCG_TYPE_I32, tcg_target_call_iarg_regs[3],
l->mem_index);
- }
- /* 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
- */
+ pc = do_getpc(l->raddr);
+ if (ARRAY_SIZE(tcg_target_call_iarg_regs) > 4) {
+ tcg_out_movi(s, TCG_TYPE_PTR, tcg_target_call_iarg_regs[4], pc);
+ } else if (pc == (int32_t)pc) {
+ tcg_out_sti(s, TCG_TYPE_PTR, TCG_REG_ESP, 0, pc);
+ } else {
+ tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_RAX, pc);
+ tcg_out_st(s, TCG_TYPE_PTR, TCG_REG_RAX, TCG_REG_ESP, 0);
+ }
+ }
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)(l->raddr - s->code_ptr - 4);
- s->code_ptr += 4;
-
- /* Jump to the code corresponding to next IR of qemu_st */
tcg_out_jmp(s, (tcg_target_long)l->raddr);
}