Re: [Qemu-devel] [PATCH 1/2] tcg-arm: Implement tcg_register_jit

[Richard Henderson <rth@twiddle.net>]

Ping.

r~

On 05/24/2013 02:20 PM, Richard Henderson wrote:
> Allows unwinding past the code_gen_buffer.
> 
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  tcg/arm/tcg-target.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 82 insertions(+), 9 deletions(-)
> 
> diff --git a/tcg/arm/tcg-target.c b/tcg/arm/tcg-target.c
> index 3d43412..4a691b1 100644
> --- a/tcg/arm/tcg-target.c
> +++ b/tcg/arm/tcg-target.c
> @@ -2100,23 +2100,31 @@ static inline void tcg_out_movi(TCGContext *s, TCGType type,
>      tcg_out_movi32(s, COND_AL, ret, arg);
>  }
>  
> +/* Compute frame size via macros, to share between tcg_target_qemu_prologue
> +   and tcg_register_jit.  */
> +
> +#define PUSH_SIZE  ((11 - 4 + 1 + 1) * sizeof(tcg_target_long))
> +
> +#define FRAME_SIZE \
> +    ((PUSH_SIZE \
> +      + TCG_STATIC_CALL_ARGS_SIZE \
> +      + CPU_TEMP_BUF_NLONGS * sizeof(long) \
> +      + TCG_TARGET_STACK_ALIGN - 1) \
> +     & -TCG_TARGET_STACK_ALIGN)
> +
>  static void tcg_target_qemu_prologue(TCGContext *s)
>  {
> -    int frame_size;
> +    int stack_addend;
>  
>      /* Calling convention requires us to save r4-r11 and lr.  */
>      /* stmdb sp!, { r4 - r11, lr } */
>      tcg_out32(s, (COND_AL << 28) | 0x092d4ff0);
>  
> -    /* Allocate the local stack frame.  */
> -    frame_size = TCG_STATIC_CALL_ARGS_SIZE;
> -    frame_size += CPU_TEMP_BUF_NLONGS * sizeof(long);
> -    /* We saved an odd number of registers above; keep an 8 aligned stack.  */
> -    frame_size = ((frame_size + TCG_TARGET_STACK_ALIGN - 1)
> -                  & -TCG_TARGET_STACK_ALIGN) + 4;
> +    /* Reserve callee argument and tcg temp space.  */
> +    stack_addend = FRAME_SIZE - PUSH_SIZE;
>  
>      tcg_out_dat_rI(s, COND_AL, ARITH_SUB, TCG_REG_CALL_STACK,
> -                   TCG_REG_CALL_STACK, frame_size, 1);
> +                   TCG_REG_CALL_STACK, stack_addend, 1);
>      tcg_set_frame(s, TCG_REG_CALL_STACK, TCG_STATIC_CALL_ARGS_SIZE,
>                    CPU_TEMP_BUF_NLONGS * sizeof(long));
>  
> @@ -2127,8 +2135,73 @@ static void tcg_target_qemu_prologue(TCGContext *s)
>  
>      /* Epilogue.  We branch here via tb_ret_addr.  */
>      tcg_out_dat_rI(s, COND_AL, ARITH_ADD, TCG_REG_CALL_STACK,
> -                   TCG_REG_CALL_STACK, frame_size, 1);
> +                   TCG_REG_CALL_STACK, stack_addend, 1);
>  
>      /* ldmia sp!, { r4 - r11, pc } */
>      tcg_out32(s, (COND_AL << 28) | 0x08bd8ff0);
>  }
> +
> +typedef struct {
> +    uint32_t len __attribute__((aligned((sizeof(void *)))));
> +    uint32_t id;
> +    uint8_t version;
> +    char augmentation[1];
> +    uint8_t code_align;
> +    uint8_t data_align;
> +    uint8_t return_column;
> +} DebugFrameCIE;
> +
> +typedef struct {
> +    uint32_t len __attribute__((aligned((sizeof(void *)))));
> +    uint32_t cie_offset;
> +    tcg_target_long func_start __attribute__((packed));
> +    tcg_target_long func_len __attribute__((packed));
> +    uint8_t def_cfa[4];
> +    uint8_t reg_ofs[18];
> +} DebugFrameFDE;
> +
> +typedef struct {
> +    DebugFrameCIE cie;
> +    DebugFrameFDE fde;
> +} DebugFrame;
> +
> +#define ELF_HOST_MACHINE EM_ARM
> +
> +static DebugFrame debug_frame = {
> +    .cie.len = sizeof(DebugFrameCIE)-4, /* length after .len member */
> +    .cie.id = -1,
> +    .cie.version = 1,
> +    .cie.code_align = 1,
> +    .cie.data_align = 0x7c,             /* sleb128 -4 */
> +    .cie.return_column = 14,
> +
> +    .fde.len = sizeof(DebugFrameFDE)-4, /* length after .len member */
> +    .fde.def_cfa = {
> +        12, 13,                         /* DW_CFA_def_cfa sp, ... */
> +        (FRAME_SIZE & 0x7f) | 0x80,     /* ... uleb128 FRAME_SIZE */
> +        (FRAME_SIZE >> 7)
> +    },
> +    .fde.reg_ofs = {
> +        /* The following must match the stmdb in the prologue.  */
> +        0x8e, 1,                        /* DW_CFA_offset, lr, -4 */
> +        0x8b, 2,                        /* DW_CFA_offset, r11, -8 */
> +        0x8a, 3,                        /* DW_CFA_offset, r10, -12 */
> +        0x89, 4,                        /* DW_CFA_offset, r9, -16 */
> +        0x88, 5,                        /* DW_CFA_offset, r8, -20 */
> +        0x87, 6,                        /* DW_CFA_offset, r7, -24 */
> +        0x86, 7,                        /* DW_CFA_offset, r6, -28 */
> +        0x85, 8,                        /* DW_CFA_offset, r5, -32 */
> +        0x84, 9,                        /* DW_CFA_offset, r4, -36 */
> +    }
> +};
> +
> +void tcg_register_jit(void *buf, size_t buf_size)
> +{
> +    /* We're expecting a 2 byte uleb128 encoded value.  */
> +    assert(FRAME_SIZE >> 14 == 0);
> +
> +    debug_frame.fde.func_start = (tcg_target_long) buf;
> +    debug_frame.fde.func_len = buf_size;
> +
> +    tcg_register_jit_int(buf, buf_size, &debug_frame, sizeof(debug_frame));
> +}
>