[Bug target/20331] New: Wrong code generation for the argument of the pure function in PIC

[Bug target/20331] New: Wrong code generation for the argument of the pure function in PIC

[kkojima at gcc dot gnu dot org]

The C code below

extern __attribute__((pure)) int pf (int *);
extern int bar;

int foo (void) { return pf (&bar);}

is wrongly compiled with -fPIC on sh64-elf.  The output doesn't
any references to the symbol bar:

	.section	.text..SHmedia32,"ax"
	.align 2
	.global	_foo
	.type	_foo, @function
_foo:
	addi.l	r15, -24, r15
	st.l	r15, 12, r18
	st.l	r15, 8, r14
	st.l	r15, 4, r12
	movi	(((datalabel _GLOBAL_OFFSET_TABLE_-(.LPCS0-.)) >> 16) & 65535), r12
	shori	((datalabel _GLOBAL_OFFSET_TABLE_-(.LPCS0-.)) & 65535), r12
	.LPCS0: ptrel/u	r12, tr0
	gettr	tr0, r12
	add.l	r15, r63, r14
	ld.l	r2, 0, r2
	movi	(((_pf@GOTPLT) >> 16) & 65535), r1
	shori	((_pf@GOTPLT) & 65535), r1
	ldx.l	r1, r12, r1
	ptabs	r1, tr0
	blink	tr0, r18
	add.l	r14, r63, r15
	ld.l	r15, 4, r12
	ld.l	r15, 8, r14
	ld.l	r15, 12, r18
	addi.l	r15, 24, r15
	ptabs	r18, tr0
	blink	tr0, r63
	.size	_foo, .-_foo

I confirmed that 3.4/4.0 behaves same and 3.3.6 compiler produces
the sane code.  So this is a regression from 3.3 to 3.4/4.0/4.1.

-- 
           Summary: Wrong code generation for the argument of the pure
                    function in PIC
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P2
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kkojima at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: sh64-unknown-elf


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug target/20331] Wrong code generation for the argument of the pure function in PIC

[kkojima at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |3.4.4 4.0.1 4.1.0
      Known to work|                            |3.3.6


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug target/20331] [3.4/4.0/41 Regression] Wrong code generation for the argument of the pure function in PIC

[giovannibajo at libero dot it]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Wrong code generation for   |[3.4/4.0/41 Regression]
                   |the argument of the pure    |Wrong code generation for
                   |function in PIC             |the argument of the pure
                   |                            |function in PIC


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug target/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[giovannibajo at libero dot it]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[3.4/4.0/41 Regression]     |[3.4/4.0/4.1 Regression]
                   |Wrong code generation for   |Wrong code generation for
                   |the argument of the pure    |the argument of the pure
                   |function in PIC             |function in PIC


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug target/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.1.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug target/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[kkojima at gcc dot gnu dot org]

------- Additional Comments From kkojima at gcc dot gnu dot org  2005-03-07 00:20 -------
I've traced what's going on:
  http://gcc.gnu.org/ml/gcc-patches/2005-03/msg00525.html
It includes a patch for comment.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug target/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[amylaar at gcc dot gnu dot org]

------- Additional Comments From amylaar at gcc dot gnu dot org  2005-03-08 21:58 -------
(In reply to comment #1)
> I've traced what's going on:
>   http://gcc.gnu.org/ml/gcc-patches/2005-03/msg00525.html
> It includes a patch for comment.
> 

The sh64 port is partcularily exposed in emit_libcall_block because it uses
paradoxical subregs to set up the offset part of the PIC address, but I
think your patch makes sense.  Except that this is only the tip of the iceberg.
The problem was introduced in a maga-patch to remove RTX_UNCHANGING_P; there
are a number of other places that need to be fixed up similarily.

2004-08-18  Richard Henderson  <rth@redhat.com>

        * rtl.h (MEM_READONLY_P): Replace RTX_UNCHANGING_P.
        * alias.c (true_dependence): Update to match new semantics.
        (canon_true_dependence, write_dependence_p): Likewise.
        (anti_dependence, output_dependence): Update write_dependence_p args.
        (unchanging_anti_dependence): Remove.
        * calls.c (purge_mem_unchanging_flag): Remove.
        (fixup_tail_calls): Don't call it.
        (expand_call): Don't add unchanging memory to function usage.
        * expr.c (emit_block_move_via_libcall): Likewise.
        (clear_storage_via_libcall): Don't clobber RTX_UNCHANGING_P mems.
        (get_subtarget): Don't use RTX_UNCHANGING_P.
        (expand_assignment, store_constructor, expand_expr_real_1): Likewise.
        (do_tablejump): Set MEM_READONLY_P, not RTX_UNCHANGING_P.
        * combine.c (get_last_value_validate): Use MEM_READONLY_P.
        * cse.c (insert): Don't use RTX_UNCHANGING_P.
        (cse_insn, canon_hash): Use MEM_READONLY_P.
        * emit-rtl.c (set_mem_attributes_minus_bitpos): Use MEM_READONLY_P
        instead of RTX_UNCHANGING_P.
        * explow.c (maybe_set_unchanging): Remove.
        * expr.h (maybe_set_unchanging): Remove.
        * flow.c (insn_dead_p, mark_used_regs): Use anti_dependence.
        * function.c (assign_stack_temp_for_type): Don't use RTX_UNCHANGING_P.
        (assign_parm_setup_reg, expand_function_start): Likewise.
        * integrate.c (copy_rtx_and_substitute): Likewise.
        * ra-rewrite.c (emit_colors): Likewise.
        * regmove.c (copy_src_to_dest, regmove_optimize): Likewise.
        (fixup_match_1): Likewise.
        * reload1.c (reload, alter_reg): Likewise.
        * local-alloc.c (validate_equiv_mem): Check MEM_READONLY_P,
        not RTX_UNCHANGING_P.
        (equiv_init_varies_p): Likewise.
        * loop-invariant.c (check_maybe_invariant): Likewise.
        * resource.c (mark_referenced_resources, mark_set_resources): Likewise.
        * loop.c (note_addr_stored): Likewise.
        (prescan_loop): Likewise. Don't check function usage for clobbered
        unchanging memory.
        * rtlanal.c (rtx_unstable_p): Check MEM_READONLY_P,
        not RTX_UNCHANGING_P.
        (rtx_varies_p, modified_between_p, modified_in_p): Likewise.
        * varasm.c (force_const_mem): Likewise.
        * stmt.c (expand_decl): Don't set RTX_UNCHANGING_P.
        * web.c (entry_register): Likewise.
        * tree-gimple.h (get_base_address): Move decl ...
        * tree.h: ... here.
        * doc/rtl.texi (MEM_READONLY_P): Replace RTX_UNCHANGING_P.

        * config/alpha/alpha.c (alpha_set_memflags_1): Rewrite to be
        called via for_each_rtx.  Copy MEM_SCALAR_P, MEM_NOTRAP_P too.
        (alpha_set_memflags): Update to match.

        * config/darwin.c (machopic_indirect_data_reference): Set
        MEM_READONLY_P instead of RTX_UNCHANGING_P.
        (machopic_indirect_call_target): Likewise.
        (machopic_legitimize_pic_address): Likewise.
        * config/arm/arm.c (legitimize_pic_address, arm_gen_load_multiple,
        arm_gen_store_multiple, arm_gen_movmemqi): Likewise.
        * config/arm/arm.md (load_multiple, store_multiple): Likewise.
        * config/frv/frv.md (symGOT2reg): Likewise.
        * config/i386/i386.c (legitimize_pic_address,
        legitimize_tls_address, ix86_split_to_parts): Likewise.
        * config/ia64/ia64.c (ia64_expand_tls_address): Likewise.
        * config/ia64/ia64.md (load_fptr): Likewise.
        * config/m32r/m32r.c (m32r_legitimize_pic_address): Likewise.
        * config/m68k/m68k.c (legitimize_pic_address): Likewise.
        * config/mcore/mcore.c (block_move_sequence): Likewise.
        * config/mn10300/mn10300.md (symGOT2reg): Likewise.
        * config/pa/pa.c (legitimize_pic_address): Likewise.
        * config/rs6000/rs6000.c (rs6000_legitimize_tls_address): Likewise.
        (rs6000_emit_move): Likewise.
        * config/s390/s390.c (legitimize_pic_address): Likewise.
        (legitimize_tls_address): Likewise.
        * config/s390/s390.md (casesi): Likewise.
        * config/sh/sh.c (prepare_move_operands, sh_reorg): Likewise.
        * config/sh/sh.md (symGOT2reg): Likewise.
        * config/sparc/sparc.c (legitimize_pic_address): Likewise.
        * config/v850/v850.md (casesi): Likewise.

        * config/ia64/ia64.c (gen_thread_pointer): Don't set RTX_UNCHANGING_P.
        * config/iq2000/iq2000.c (save_restore_insns): Likewise.
        * config/mips/mips.c (mips_restore_gp): Likewise.
        (mips_save_restore_reg, mips16_gp_pseudo_reg): Likewise.
        * config/sh/sh.c (sh_reorg): Likewise.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |amylaar at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-03-08 21:58:34
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug target/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[kkojima at gcc dot gnu dot org]

------- Additional Comments From kkojima at gcc dot gnu dot org  2005-03-09 23:58 -------
I'm taking a look at the uses of MEM_READONLY_P, though I'm not
sure which one has the similar issue.  It looks that modified_in_p
has the same problem with modified_between_p.
BTW, it's better to change the component of this PR, isn't it?
rtl-optimization?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug rtl-optimization/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[giovannibajo at libero dot it]

------- Additional Comments From giovannibajo at libero dot it  2005-03-10 00:12 -------
CC'ing RTH since he's the one who removed RTX_UNCHANGING.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rth at gcc dot gnu dot org
          Component|target                      |rtl-optimization


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug rtl-optimization/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[amylaar at gcc dot gnu dot org]

------- Additional Comments From amylaar at gcc dot gnu dot org  2005-03-10 04:24 -------
(In reply to comment #3)
> I'm taking a look at the uses of MEM_READONLY_P, though I'm not
> sure which one has the similar issue.  It looks that modified_in_p
> has the same problem with modified_between_p.

Yes, that's also the one I spotted first.  But it's simple to find more:
grep tells us alias.c has some MEM_READONLY_P.  Bingo, the first hit is
another instance: true_dependence does:

  if (MEM_READONLY_P (x))
    return 0;

without checking if x contains a MEM that is dependent (possible if the
target supports memory-indirect addressing, e.g. m68020)



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug rtl-optimization/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-03-10 13:57 -------
I'll agree that modified_{in,between}_p need to check the address for changes,
since that controls the ultimate value that is accessed.

I do not agree that alias.c needs to check the address for changes.  In that
case we're trying to determine if assigning a value to one memory reference
can possibly change the value of another memory reference.  Which is false for
*all* read-only memory.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug rtl-optimization/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[joern dot rennecke at st dot com]

------- Additional Comments From joern dot rennecke at st dot com  2005-03-10 18:18 -------
Subject: Re:  [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

rth at gcc dot gnu dot org wrote:

>------- Additional Comments From rth at gcc dot gnu dot org  2005-03-10 13:57 -------
>I'll agree that modified_{in,between}_p need to check the address for changes,
>since that controls the ultimate value that is accessed.
>
>I do not agree that alias.c needs to check the address for changes.  In that
>case we're trying to determine if assigning a value to one memory reference
>can possibly change the value of another memory reference.  Which is false for
>*all* read-only memory.
>
>  
>
After looking a bit more at true_dependence and friends, I think you are 
right; the callers have
checked or will be checking the address.  And apart from the dependency 
functions in alias.c,
I could find only modified_{in,between}_p using MEM_READONLY_P to 
indicate that the
entire MEM doesn't change.



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug rtl-optimization/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-03-11 03:14 -------
Subject: Bug 20331

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	kkojima@gcc.gnu.org	2005-03-11 03:14:45

Modified files:
	gcc            : ChangeLog rtlanal.c 

Log message:
	PR rtl-optimization/20331
	* rtlanal.c (modified_between_p): Check its address first for MEM.
	(modified_in_p): Likewise.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.7780&r2=2.7781
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/rtlanal.c.diff?cvsroot=gcc&r1=1.211&r2=1.212



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug rtl-optimization/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-03-31 23:21 -------
Is this fixed now that a patch has been applied?

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug rtl-optimization/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[kkojima at gcc dot gnu dot org]

------- Additional Comments From kkojima at gcc dot gnu dot org  2005-03-31 23:57 -------
On 4.1, yes.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug rtl-optimization/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-04-01 00:00 -------
It's marked as a 4.0 regression.  Do you plan on applying the patch there?
If not, we should simply close the bug.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug rtl-optimization/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[kkojima at gcc dot gnu dot org]

------- Additional Comments From kkojima at gcc dot gnu dot org  2005-04-01 00:51 -------
It causes the failure only for sh64 target and can be found only
at 4.x java runtime for that target on which 4.0 jave doesn't
work without many other patches.  So there would be no reason to
apply it to 4.0 and it'd be enough to close this PR.



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331

[Bug rtl-optimization/20331] [3.4/4.0/4.1 Regression] Wrong code generation for the argument of the pure function in PIC

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-04-01 01:17 -------
Fine.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20331