[Bug middle-end/66334] New: cleanup block fails to initialize EBX

["hjl.tools at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66334

            Bug ID: 66334
           Summary: cleanup block fails to initialize EBX
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
                CC: ubizjak at gmail dot com
  Target Milestone: ---
            Target: i?86-linux

[hjl@gnu-tools-1 tmp]$ cat x.i
extern int foo (int);
extern void exit (int __status) __attribute__ ((__nothrow__ )) __attribute__
((__noreturn__));
struct __pthread_cleanup_frame
{
  void (*__cancel_routine) (void *);
  void *__cancel_arg;
  int __do_it;
  int __cancel_type;
};
extern __inline void
__pthread_cleanup_routine (struct __pthread_cleanup_frame *__frame)
{
  if (__frame->__do_it)
    __frame->__cancel_routine (__frame->__cancel_arg);
}
static int cl_called;

static void
cl (void *arg)
{
  ++cl_called;
}


void *
tf_usleep (void *arg)
{

  do { struct __pthread_cleanup_frame __clframe __attribute__ ((__cleanup__
(__pthread_cleanup_routine))) = { .__cancel_routine = (cl), .__cancel_arg = (
 ((void *)0)), .__do_it = 1 };;

  foo (arg == ((void *)0) ? (0x7fffffffL * 2UL + 1UL) : 0);

  __clframe.__do_it = (0); } while (0);

  exit (1);
}
[hjl@gnu-tools-1 tmp]$ /usr/gcc-6.0.0-pie/bin/gcc -fexceptions
-fasynchronous-unwind-tables -m32 -S -O2 /tmp/x.i     -fpic
[hjl@gnu-tools-1 tmp]$ cat x.s
        .file   "x.i"
        .section        .text.unlikely,"ax",@progbits
.LCOLDB0:
        .text
.LHOTB0:
        .p2align 4,,15
        .type   cl, @function
cl:
.LFB1:
        .cfi_startproc
        call    __x86.get_pc_thunk.ax
        addl    $_GLOBAL_OFFSET_TABLE_, %eax
        addl    $1, cl_called@GOTOFF(%eax)
        ret
        .cfi_endproc
.LFE1:
        .size   cl, .-cl
        .section        .text.unlikely
.LCOLDE0:
        .text
.LHOTE0:
        .section        .text.unlikely
.LCOLDB1:
        .text
.LHOTB1:
        .p2align 4,,15
        .globl  __pthread_cleanup_routine
        .type   __pthread_cleanup_routine, @function
__pthread_cleanup_routine:
.LFB0:
        .cfi_startproc
        movl    4(%esp), %eax
        movl    8(%eax), %edx
        testl   %edx, %edx
        jne     .L5
        rep ret
        .p2align 4,,10
        .p2align 3
.L5:
        movl    4(%eax), %edx
        movl    %edx, 4(%esp)
        jmp     *(%eax)
        .cfi_endproc
.LFE0:
        .size   __pthread_cleanup_routine, .-__pthread_cleanup_routine
        .section        .text.unlikely
.LCOLDE1:
        .text
.LHOTE1:
        .section        .text.unlikely
.LCOLDB2:
        .text
.LHOTB2:
        .p2align 4,,15
        .globl  tf_usleep
        .type   tf_usleep, @function
tf_usleep:
.LFB2:
        .cfi_startproc
        .cfi_personality 0x9b,DW.ref.__gcc_personality_v0
        .cfi_lsda 0x1b,.LLSDA2
        pushl   %ebp
        .cfi_def_cfa_offset 8
        .cfi_offset 5, -8
        xorl    %eax, %eax
        movl    %esp, %ebp
        .cfi_def_cfa_register 5
        pushl   %esi
        pushl   %ebx
        .cfi_offset 6, -12
        .cfi_offset 3, -16
        movl    8(%ebp), %edx
        subl    $12, %esp
        call    __x86.get_pc_thunk.bx
        addl    $_GLOBAL_OFFSET_TABLE_, %ebx
        testl   %edx, %edx
        sete    %al
        negl    %eax
        pushl   %eax
.LEHB0:
        .cfi_escape 0x2e,0x10
        call    foo@PLT
.LEHE0:
        movl    $1, (%esp)
        call    exit@PLT
.L8:
        subl    $12, %esp
        movl    %eax, %esi
        pushl   $0
        call    cl
        movl    %esi, (%esp)
.LEHB1:
        call    _Unwind_Resume@PLT
.LEHE1:
        .cfi_endproc
.LFE2:
        .globl  __gcc_personality_v0
        .section        .gcc_except_table,"a",@progbits
.LLSDA2:
        .byte   0xff
        .byte   0xff
        .byte   0x1
        .uleb128 .LLSDACSE2-.LLSDACSB2
.LLSDACSB2:
        .uleb128 .LEHB0-.LFB2
        .uleb128 .LEHE0-.LEHB0
        .uleb128 .L8-.LFB2
        .uleb128 0
        .uleb128 .LEHB1-.LFB2
        .uleb128 .LEHE1-.LEHB1
        .uleb128 0
        .uleb128 0
.LLSDACSE2:
        .text
        .size   tf_usleep, .-tf_usleep
        .section        .text.unlikely
.LCOLDE2:
        .text
.LHOTE2:
        .local  cl_called
        .comm   cl_called,4,4
        .section       
.text.__x86.get_pc_thunk.ax,"axG",@progbits,__x86.get_pc_thunk.ax,comdat
        .globl  __x86.get_pc_thunk.ax
        .hidden __x86.get_pc_thunk.ax
        .type   __x86.get_pc_thunk.ax, @function
__x86.get_pc_thunk.ax:
.LFB4:
        .cfi_startproc
        movl    (%esp), %eax
        ret
        .cfi_endproc
.LFE4:
        .section       
.text.__x86.get_pc_thunk.bx,"axG",@progbits,__x86.get_pc_thunk.bx,comdat
        .globl  __x86.get_pc_thunk.bx
        .hidden __x86.get_pc_thunk.bx
        .type   __x86.get_pc_thunk.bx, @function
__x86.get_pc_thunk.bx:
.LFB5:
        .cfi_startproc
        movl    (%esp), %ebx
        ret
        .cfi_endproc
.LFE5:
        .hidden DW.ref.__gcc_personality_v0
        .weak   DW.ref.__gcc_personality_v0
        .section       
.data.DW.ref.__gcc_personality_v0,"awG",@progbits,DW.ref.__gcc_personality_v0,comdat
        .align 4
        .type   DW.ref.__gcc_personality_v0, @object
        .size   DW.ref.__gcc_personality_v0, 4
DW.ref.__gcc_personality_v0:
        .long   __gcc_personality_v0
        .ident  "GCC: (GNU) 6.0.0 20150528 (experimental)"
        .section        .note.GNU-stack,"",@progbits
[hjl@gnu-tools-1 tmp]$ 

The problem is

.L8:
        subl    $12, %esp
        movl    %eax, %esi
        pushl   $0
        call    cl
        movl    %esi, (%esp)
.LEHB1:
        call    _Unwind_Resume@PLT
.LEHE1:

This cleanup block is called via

        .section        .gcc_except_table,"a",@progbits
.LLSDA2:
        .byte   0xff
        .byte   0xff
        .byte   0x1
        .uleb128 .LLSDACSE2-.LLSDACSB2
.LLSDACSB2:
        .uleb128 .LEHB0-.LFB2
        .uleb128 .LEHE0-.LEHB0
        .uleb128 .L8-.LFB2
        .uleb128 0
        .uleb128 .LEHB1-.LFB2
        .uleb128 .LEHE1-.LEHB1
        .uleb128 0
        .uleb128 0
.LLSDACSE2:

When the cleanup block is entered, EBX isn't valid.  In PIC, the cleanup
block must initialize EBX before branching to PLT.