mirror_qemu/accel/tcg
Markus Armbruster 668f62ec62 error: Eliminate error_propagate() with Coccinelle, part 1
When all we do with an Error we receive into a local variable is
propagating to somewhere else, we can just as well receive it there
right away.  Convert

    if (!foo(..., &err)) {
        ...
        error_propagate(errp, err);
        ...
        return ...
    }

to

    if (!foo(..., errp)) {
        ...
        ...
        return ...
    }

where nothing else needs @err.  Coccinelle script:

    @rule1 forall@
    identifier fun, err, errp, lbl;
    expression list args, args2;
    binary operator op;
    constant c1, c2;
    symbol false;
    @@
         if (
    (
    -        fun(args, &err, args2)
    +        fun(args, errp, args2)
    |
    -        !fun(args, &err, args2)
    +        !fun(args, errp, args2)
    |
    -        fun(args, &err, args2) op c1
    +        fun(args, errp, args2) op c1
    )
            )
         {
             ... when != err
                 when != lbl:
                 when strict
    -        error_propagate(errp, err);
             ... when != err
    (
             return;
    |
             return c2;
    |
             return false;
    )
         }

    @rule2 forall@
    identifier fun, err, errp, lbl;
    expression list args, args2;
    expression var;
    binary operator op;
    constant c1, c2;
    symbol false;
    @@
    -    var = fun(args, &err, args2);
    +    var = fun(args, errp, args2);
         ... when != err
         if (
    (
             var
    |
             !var
    |
             var op c1
    )
            )
         {
             ... when != err
                 when != lbl:
                 when strict
    -        error_propagate(errp, err);
             ... when != err
    (
             return;
    |
             return c2;
    |
             return false;
    |
             return var;
    )
         }

    @depends on rule1 || rule2@
    identifier err;
    @@
    -    Error *err = NULL;
         ... when != err

Not exactly elegant, I'm afraid.

The "when != lbl:" is necessary to avoid transforming

         if (fun(args, &err)) {
             goto out
         }
         ...
     out:
         error_propagate(errp, err);

even though other paths to label out still need the error_propagate().
For an actual example, see sclp_realize().

Without the "when strict", Coccinelle transforms vfio_msix_setup(),
incorrectly.  I don't know what exactly "when strict" does, only that
it helps here.

The match of return is narrower than what I want, but I can't figure
out how to express "return where the operand doesn't use @err".  For
an example where it's too narrow, see vfio_intx_enable().

Silently fails to convert hw/arm/armsse.c, because Coccinelle gets
confused by ARMSSE being used both as typedef and function-like macro
there.  Converted manually.

Line breaks tidied up manually.  One nested declaration of @local_err
deleted manually.  Preexisting unwanted blank line dropped in
hw/riscv/sifive_e.c.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200707160613.848843-35-armbru@redhat.com>
2020-07-10 15:18:08 +02:00
..
Makefile.objs plugin-gen: add module for TCG-related code 2019-10-28 15:12:38 +00:00
atomic_common.inc.c tcg: let plugins instrument virtual memory accesses 2019-10-28 15:12:38 +00:00
atomic_template.h trace: Remove trace_mem_build_info_no_se_[bl]e 2020-01-15 15:13:09 -10:00
cpu-exec-common.c qemu-common: Move tcg_enabled() etc. to sysemu/tcg.h 2019-06-11 20:22:09 +02:00
cpu-exec.c accel/tcg: fix race in cpu_exec_step_atomic (bug 1863025) 2020-02-28 10:58:41 -08:00
cputlb.c cputlb: destroy CPUTLB with tlb_destroy 2020-06-16 14:49:05 +01:00
plugin-gen.c plugin-gen: add module for TCG-related code 2019-10-28 15:12:38 +00:00
plugin-helpers.h plugin-gen: add module for TCG-related code 2019-10-28 15:12:38 +00:00
tcg-all.c error: Eliminate error_propagate() with Coccinelle, part 1 2020-07-10 15:18:08 +02:00
tcg-runtime-gvec.c tcg: Implement gvec support for rotate by vector 2020-06-02 08:42:37 -07:00
tcg-runtime.c tcg: Search includes from the project root source directory 2020-01-15 15:13:10 -10:00
tcg-runtime.h tcg: Implement gvec support for rotate by vector 2020-06-02 08:42:37 -07:00
trace-events accel/tcg: don't disable exec_tb trace events 2020-05-15 15:25:16 +01:00
translate-all.c osdep: Make MIN/MAX evaluate arguments only once 2020-06-26 09:39:39 -04:00
translate-all.h cputlb: Pass retaddr to tb_check_watchpoint 2019-09-25 10:56:28 -07:00
translator.c qemu_log_lock/unlock now preserves the qemu_logfile handle. 2019-12-18 20:18:02 +00:00
user-exec-stub.c hw/core: Move cpu.c, cpu.h from qom/ to hw/core/ 2019-08-21 13:24:01 +02:00
user-exec.c accel/tcg: Provide a NetBSD specific aarch64 cpu_signal_handler 2020-06-02 08:42:37 -07:00