[Bug target/108919] New: pure nested function may clobber its static chain pointer in windowed ABI on xtensa

[Bug target/108919] New: pure nested function may clobber its static chain pointer in windowed ABI on xtensa

[jcmvbkbc at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108919

            Bug ID: 108919
           Summary: pure nested function may clobber its static chain
                    pointer in windowed ABI on xtensa
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jcmvbkbc at gcc dot gnu.org
  Target Milestone: ---

Created attachment 54525
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54525&action=edit
test.c

The following gfortran tests fail on windowed ABI xtensa target, but pass on
call0 ABI:

gfortran.dg/character_workout_1.f90   -O[123s]  execution test
gfortran.dg/character_workout_4.f90   -O[123s]  execution test

E.g. gfortran.dg/character_workout_1.f90 -O1 ends with the message 'STOP 209'.

This happens because in these tests pure nested functions are generated for
subroutines achar_cm and achar_am and the fwprop1 pass removes static chain
pointer initialization between the calls to these functions:

.L143:  
        addi    a3, sp, 108
        movi    a4, 0xd4
        add.n   a4, sp, a4
        addi    a8, sp, -20
        s32i.n  a4, a8, 0
        movi.n  a11, 7
        mov.n   a10, a3
        call8   achar_cm.21
        movi.n  a11, 7
        mov.n   a10, a3
        call8   achar_am.15

Windowed ABI for xtensa specifies that the static chain is passed on the stack,
at offset -20 from the called function's CFA, i.e. outside the caller's stack
frame. This location may be overwritten if the called function makes function
calls that exceed certain depth.

The issue may be reproduced with the attached small test case.

[Bug target/108919] pure nested function may clobber its static chain pointer in windowed ABI on xtensa

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108919

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Max Filippov <jcmvbkbc@gcc.gnu.org>:

https://gcc.gnu.org/g:461d3c84a0e5ad045ee54631901cc953d6befa20

commit r13-6342-g461d3c84a0e5ad045ee54631901cc953d6befa20
Author: Max Filippov <jcmvbkbc@gmail.com>
Date:   Wed Feb 22 14:17:11 2023 -0800

    gcc: xtensa: fix PR target/108919

    gcc/
            PR target/108919

            * config/xtensa/xtensa-protos.h
            (xtensa_prepare_expand_call): Rename to xtensa_expand_call.
            * config/xtensa/xtensa.cc (xtensa_prepare_expand_call): Rename
            to xtensa_expand_call.
            (xtensa_expand_call): Emit the call and add a clobber expression
            for the static chain to it in case of windowed ABI.
            * config/xtensa/xtensa.md (call, call_value, sibcall)
            (sibcall_value): Call xtensa_expand_call and complete expansion
            right after that call.

    gcc/testsuite/
            * gcc.target/xtensa/pr108919.c: New test.

[Bug target/108919] pure nested function may clobber its static chain pointer in windowed ABI on xtensa

[jcmvbkbc at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108919

jcmvbkbc at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #2 from jcmvbkbc at gcc dot gnu.org ---
Fix is committed to the master.