Re: [Qemu-devel] [PATCH 0/2] tcg: Fix launchpad 1824853

[Philippe Mathieu-Daudé]

On 4/16/19 10:31 AM, Richard Henderson wrote:
> This is a case where we generate more than 64k code for a mere 231
> guest instructions.  This hits some assertions within TCG that we're
> not overflowing the uint16_t that we use for representing our
> unwind info.
> 
> Fix this by returning an error indication, rather than asserting.
> This lets us try again from tb_gen_code with a lower max_insns.
> 
> This should resolve the problem for x86 as a host.  There are other
> failure modes wrt out-of-range relocations that might affect the
> RISC hosts.  I'm going to leave those for a different patch set.

Very clean way to solve this. Nice cleanup in patch #1 (interesting
Nios2 case), Simple fix in patch #2. It would be fun to trigger the
assert(max_insns > 1) =)

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

> Richard Henderson (2):
>   tcg: Hoist max_insns computation to tb_gen_code
>   tcg: Restart after TB code generation overflow
> 
>  include/exec/exec-all.h       |  4 +--
>  include/exec/translator.h     |  3 +-
>  accel/tcg/translate-all.c     | 54 +++++++++++++++++++++++++++++------
>  accel/tcg/translator.c        | 15 ++--------
>  target/alpha/translate.c      |  4 +--
>  target/arm/translate.c        |  4 +--
>  target/cris/translate.c       | 10 +------
>  target/hppa/translate.c       |  5 ++--
>  target/i386/translate.c       |  4 +--
>  target/lm32/translate.c       | 10 +------
>  target/m68k/translate.c       |  4 +--
>  target/microblaze/translate.c | 10 +------
>  target/mips/translate.c       |  4 +--
>  target/moxie/translate.c      | 11 ++-----
>  target/nios2/translate.c      | 14 ++-------
>  target/openrisc/translate.c   |  4 +--
>  target/ppc/translate.c        |  4 +--
>  target/riscv/translate.c      |  4 +--
>  target/s390x/translate.c      |  4 +--
>  target/sh4/translate.c        |  4 +--
>  target/sparc/translate.c      |  4 +--
>  target/tilegx/translate.c     | 12 +-------
>  target/tricore/translate.c    | 16 ++---------
>  target/unicore32/translate.c  | 10 +------
>  target/xtensa/translate.c     |  4 +--
>  tcg/tcg.c                     |  4 +++
>  26 files changed, 93 insertions(+), 133 deletions(-)
>