Small patch for exit_tb.  Large reorg for goto_tb, primarily aimed at
fixing a race condition in which a host thread gets suspended in the
middle of executing a two insn sequence, and the sequence is updated.
The updated second insn does not match the previous first insn, so
when the thread restarts the entire sequence will not branch to either
the old or the new destination.

The middle-end is adjusted to support both direct and indirect jumps
simultaneously, instead of depending on TCG_TARGET_HAS_direct_jump.
This allows the backend to decide whether to use direct or indirect
based on the branch displacement.  Which allows us to only update a
single instruction, which means there's no multi-insn sequence that
can be interrupted.

Changes for v2:
  * Rebase on master,
  * Remove if (0) accidentially left in tcg/sparc64/.


r~


Richard Henderson (22):
  tcg: Split out tcg_out_exit_tb
  tcg/i386: Remove unused goto_tb code for indirect jump
  tcg/ppc: Remove unused goto_tb code for indirect jump
  tcg/sparc64: Remove unused goto_tb code for indirect jump
  tcg: Replace asserts on tcg_jmp_insn_offset
  tcg: Introduce set_jmp_insn_offset
  tcg: Introduce get_jmp_target_addr
  tcg: Split out tcg_out_goto_tb
  tcg: Rename TB_JMP_RESET_OFFSET_INVALID to TB_JMP_OFFSET_INVALID
  tcg: Add gen_tb to TCGContext
  tcg: Add TranslationBlock.jmp_insn_offset
  tcg: Change tb_target_set_jmp_target arguments
  tcg: Move tb_target_set_jmp_target declaration to tcg.h
  tcg: Always define tb_target_set_jmp_target
  tcg: Remove TCG_TARGET_HAS_direct_jump
  tcg/aarch64: Reorg goto_tb implementation
  tcg/ppc: Reorg goto_tb implementation
  tcg/sparc64: Remove USE_REG_TB
  tcg/sparc64: Reorg goto_tb implementation
  tcg/arm: Implement direct branch for goto_tb
  tcg/riscv: Introduce OPC_NOP
  tcg/riscv: Implement direct branch for goto_tb

 include/exec/exec-all.h          |   5 +-
 include/tcg/tcg.h                |  14 +--
 tcg/aarch64/tcg-target.h         |   7 +-
 tcg/arm/tcg-target.h             |   5 -
 tcg/i386/tcg-target.h            |   9 --
 tcg/loongarch64/tcg-target.h     |   3 -
 tcg/mips/tcg-target.h            |   5 -
 tcg/ppc/tcg-target.h             |   7 +-
 tcg/riscv/tcg-target.h           |   4 -
 tcg/s390x/tcg-target.h           |  11 --
 tcg/sparc64/tcg-target.h         |   4 -
 tcg/tci/tcg-target.h             |   4 -
 accel/tcg/cpu-exec.c             |  16 ++-
 accel/tcg/translate-all.c        |  10 +-
 tcg/tcg-op.c                     |  14 +--
 tcg/tcg.c                        |  42 +++++--
 tcg/aarch64/tcg-target.c.inc     | 104 ++++++++--------
 tcg/arm/tcg-target.c.inc         |  89 +++++++++-----
 tcg/i386/tcg-target.c.inc        |  68 ++++++-----
 tcg/loongarch64/tcg-target.c.inc |  66 +++++-----
 tcg/mips/tcg-target.c.inc        |  59 +++++----
 tcg/ppc/tcg-target.c.inc         | 193 +++++++++--------------------
 tcg/riscv/tcg-target.c.inc       |  65 +++++++---
 tcg/s390x/tcg-target.c.inc       |  67 +++++++----
 tcg/sparc64/tcg-target.c.inc     | 201 ++++++++++++-------------------
 tcg/tci/tcg-target.c.inc         |  31 +++--
 26 files changed, 522 insertions(+), 581 deletions(-)

-- 
2.34.1

Ping.

r~

On 1/8/23 15:42, Richard Henderson wrote:
> Small patch for exit_tb.  Large reorg for goto_tb, primarily aimed at
> fixing a race condition in which a host thread gets suspended in the
> middle of executing a two insn sequence, and the sequence is updated.
> The updated second insn does not match the previous first insn, so
> when the thread restarts the entire sequence will not branch to either
> the old or the new destination.
> 
> The middle-end is adjusted to support both direct and indirect jumps
> simultaneously, instead of depending on TCG_TARGET_HAS_direct_jump.
> This allows the backend to decide whether to use direct or indirect
> based on the branch displacement.  Which allows us to only update a
> single instruction, which means there's no multi-insn sequence that
> can be interrupted.
> 
> Changes for v2:
>    * Rebase on master,
>    * Remove if (0) accidentially left in tcg/sparc64/.
> 
> 
> r~
> 
> 
> Richard Henderson (22):
>    tcg: Split out tcg_out_exit_tb
>    tcg/i386: Remove unused goto_tb code for indirect jump
>    tcg/ppc: Remove unused goto_tb code for indirect jump
>    tcg/sparc64: Remove unused goto_tb code for indirect jump
>    tcg: Replace asserts on tcg_jmp_insn_offset
>    tcg: Introduce set_jmp_insn_offset
>    tcg: Introduce get_jmp_target_addr
>    tcg: Split out tcg_out_goto_tb
>    tcg: Rename TB_JMP_RESET_OFFSET_INVALID to TB_JMP_OFFSET_INVALID
>    tcg: Add gen_tb to TCGContext
>    tcg: Add TranslationBlock.jmp_insn_offset
>    tcg: Change tb_target_set_jmp_target arguments
>    tcg: Move tb_target_set_jmp_target declaration to tcg.h
>    tcg: Always define tb_target_set_jmp_target
>    tcg: Remove TCG_TARGET_HAS_direct_jump
>    tcg/aarch64: Reorg goto_tb implementation
>    tcg/ppc: Reorg goto_tb implementation
>    tcg/sparc64: Remove USE_REG_TB
>    tcg/sparc64: Reorg goto_tb implementation
>    tcg/arm: Implement direct branch for goto_tb
>    tcg/riscv: Introduce OPC_NOP
>    tcg/riscv: Implement direct branch for goto_tb
> 
>   include/exec/exec-all.h          |   5 +-
>   include/tcg/tcg.h                |  14 +--
>   tcg/aarch64/tcg-target.h         |   7 +-
>   tcg/arm/tcg-target.h             |   5 -
>   tcg/i386/tcg-target.h            |   9 --
>   tcg/loongarch64/tcg-target.h     |   3 -
>   tcg/mips/tcg-target.h            |   5 -
>   tcg/ppc/tcg-target.h             |   7 +-
>   tcg/riscv/tcg-target.h           |   4 -
>   tcg/s390x/tcg-target.h           |  11 --
>   tcg/sparc64/tcg-target.h         |   4 -
>   tcg/tci/tcg-target.h             |   4 -
>   accel/tcg/cpu-exec.c             |  16 ++-
>   accel/tcg/translate-all.c        |  10 +-
>   tcg/tcg-op.c                     |  14 +--
>   tcg/tcg.c                        |  42 +++++--
>   tcg/aarch64/tcg-target.c.inc     | 104 ++++++++--------
>   tcg/arm/tcg-target.c.inc         |  89 +++++++++-----
>   tcg/i386/tcg-target.c.inc        |  68 ++++++-----
>   tcg/loongarch64/tcg-target.c.inc |  66 +++++-----
>   tcg/mips/tcg-target.c.inc        |  59 +++++----
>   tcg/ppc/tcg-target.c.inc         | 193 +++++++++--------------------
>   tcg/riscv/tcg-target.c.inc       |  65 +++++++---
>   tcg/s390x/tcg-target.c.inc       |  67 +++++++----
>   tcg/sparc64/tcg-target.c.inc     | 201 ++++++++++++-------------------
>   tcg/tci/tcg-target.c.inc         |  31 +++--
>   26 files changed, 522 insertions(+), 581 deletions(-)
>