On Thu, Jan 29, 2015 at 3:14 PM, Alan Modra <amo...@gmail.com> wrote:
> Here is the completed patch. Bootstrapped and regression tested
> powerpc64-linux. Is this OK to apply? If not now, then when gcc is
> in stage1 again?
It's ok to apply as it is a wrong-code fix. It would also be ok to backport
if needed.
Did you check whether other targets have function descriptors (seem
to remember the Itanic here at least)?
The middle-end changes are ok, I defer to David for the rs6000 changes.
I am also curious of the .029t.ealias dump from
gcc -O -fdump-tree-ealias-details-alias
on (the nonsensical)
void x(void);
int y;
int main()
{
void *p = x;
p+=y;
return *(int *)p;
}
Thanks,
Richard.
> gcc/
> PR target/64703
> * target.def (has_function_descriptors): New hook.
> * doc/tm.texi.in: Add TARGET_HAS_FUNCTION_DESCRIPTORS.
> * doc/tc.texi: Regenerate.
> * tree-ssa-alias.c (pt_solution_includes_base): New function,
> extracted from..
> (ref_maybe_used_by_call_p_1): ..here. Handle potential memory
> reference by indirect calls on targets using function descriptors.
> * config/rs6000/rs6000.c (TARGET_HAS_FUNCTION_DESCRIPTORS): Define.
> (rs6000_has_function_descriptors): New function.
> gcc/testsuite/
> * gcc.target/powerpc/pr64703.c: New.
>
> Index: gcc/target.def
> ===================================================================
> --- gcc/target.def (revision 220025)
> +++ gcc/target.def (working copy)
> @@ -2821,6 +2821,15 @@ The default value of this hook is based on target'
> bool, (void),
> default_has_ifunc_p)
>
> +/* True if target defines the address of a function as that of a
> + function descriptor. */
> +DEFHOOK
> +(has_function_descriptors,
> + "True if target has function descriptors and defines the address\n\
> +of a function as that of a function descriptor.",
> + bool, (void),
> + hook_bool_void_false)
> +
> /* True if it is OK to do sibling call optimization for the specified
> call expression EXP. DECL will be the called function, or NULL if
> this is an indirect call. */
> Index: gcc/doc/tm.texi.in
> ===================================================================
> --- gcc/doc/tm.texi.in (revision 220025)
> +++ gcc/doc/tm.texi.in (working copy)
> @@ -8175,6 +8175,8 @@ and the associated definitions of those functions.
>
> @hook TARGET_HAS_IFUNC_P
>
> +@hook TARGET_HAS_FUNCTION_DESCRIPTORS
> +
> @hook TARGET_ATOMIC_ALIGN_FOR_MODE
>
> @hook TARGET_ATOMIC_ASSIGN_EXPAND_FENV
> Index: gcc/doc/tm.texi
> ===================================================================
> --- gcc/doc/tm.texi (revision 220025)
> +++ gcc/doc/tm.texi (working copy)
> @@ -11510,6 +11510,11 @@ The support includes the assembler, linker and dyn
> The default value of this hook is based on target's libc.
> @end deftypefn
>
> +@deftypefn {Target Hook} bool TARGET_HAS_FUNCTION_DESCRIPTORS (void)
> +True if target has function descriptors and defines the address
> +of a function as that of a function descriptor.
> +@end deftypefn
> +
> @deftypefn {Target Hook} {unsigned int} TARGET_ATOMIC_ALIGN_FOR_MODE
> (machine_mode @var{mode})
> If defined, this function returns an appropriate alignment in bits for an
> atomic object of machine_mode @var{mode}. If 0 is returned then the default
> alignment for the specified mode is used.
> @end deftypefn
> Index: gcc/tree-ssa-alias.c
> ===================================================================
> --- gcc/tree-ssa-alias.c (revision 220025)
> +++ gcc/tree-ssa-alias.c (working copy)
> @@ -1532,6 +1532,25 @@ refs_output_dependent_p (tree store1, tree store2)
> return refs_may_alias_p_1 (&r1, &r2, false);
> }
>
> +/* Return true if the points-to solution *PT includes the object BASE. */
> +
> +static bool
> +pt_solution_includes_base (struct pt_solution *pt, tree base)
> +{
> + if (DECL_P (base))
> + return pt_solution_includes (pt, base);
> +
> + if ((TREE_CODE (base) == MEM_REF
> + || TREE_CODE (base) == TARGET_MEM_REF)
> + && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
> + {
> + struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
> + if (pi)
> + return pt_solutions_intersect (pt, &pi->pt);
> + }
> + return true;
> +}
> +
> /* If the call CALL may use the memory reference REF return true,
> otherwise return false. */
>
> @@ -1542,6 +1561,22 @@ ref_maybe_used_by_call_p_1 (gcall *call, ao_ref *r
> unsigned i;
> int flags = gimple_call_flags (call);
>
> + callee = gimple_call_fn (call);
> + if (callee && TREE_CODE (callee) == SSA_NAME
> + && targetm.has_function_descriptors ())
> + {
> + /* Handle indirect call. When a target defines the address of a
> + function as that of a function descriptor, then dereferencing
> + a function pointer implicitly references memory. */
> + struct ptr_info_def *pi = SSA_NAME_PTR_INFO (callee);
> + if (pi)
> + {
> + base = ao_ref_base (ref);
> + if (pt_solution_includes_base (&pi->pt, base))
> + return true;
> + }
> + }
> +
> /* Const functions without a static chain do not implicitly use memory. */
> if (!gimple_call_chain (call)
> && (flags & (ECF_CONST|ECF_NOVOPS)))
> @@ -1564,7 +1599,7 @@ ref_maybe_used_by_call_p_1 (gcall *call, ao_ref *r
> && !is_global_var (base))
> goto process_args;
>
> - callee = gimple_call_fndecl (call);
> + callee = gimple_call_addr_fndecl (callee);
>
> /* Handle those builtin functions explicitly that do not act as
> escape points. See tree-ssa-structalias.c:find_func_aliases
> @@ -1803,23 +1838,7 @@ ref_maybe_used_by_call_p_1 (gcall *call, ao_ref *r
> }
>
> /* Check if the base variable is call-used. */
> - if (DECL_P (base))
> - {
> - if (pt_solution_includes (gimple_call_use_set (call), base))
> - return true;
> - }
> - else if ((TREE_CODE (base) == MEM_REF
> - || TREE_CODE (base) == TARGET_MEM_REF)
> - && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
> - {
> - struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
> - if (!pi)
> - return true;
> -
> - if (pt_solutions_intersect (gimple_call_use_set (call), &pi->pt))
> - return true;
> - }
> - else
> + if (pt_solution_includes_base (gimple_call_use_set (call), base))
> return true;
>
> /* Inspect call arguments for passed-by-value aliases. */
> Index: gcc/config/rs6000/rs6000.c
> ===================================================================
> --- gcc/config/rs6000/rs6000.c (revision 220025)
> +++ gcc/config/rs6000/rs6000.c (working copy)
> @@ -1490,6 +1490,9 @@ static const struct attribute_spec rs6000_attribut
> #undef TARGET_ASM_CAN_OUTPUT_MI_THUNK
> #define TARGET_ASM_CAN_OUTPUT_MI_THUNK
> hook_bool_const_tree_hwi_hwi_const_tree_true
>
> +#undef TARGET_HAS_FUNCTION_DESCRIPTORS
> +#define TARGET_HAS_FUNCTION_DESCRIPTORS rs6000_has_function_descriptors
> +
> #undef TARGET_FUNCTION_OK_FOR_SIBCALL
> #define TARGET_FUNCTION_OK_FOR_SIBCALL rs6000_function_ok_for_sibcall
>
> @@ -22099,6 +22102,14 @@ rs6000_return_addr (int count, rtx frame)
> return get_hard_reg_initial_val (Pmode, LR_REGNO);
> }
>
> +/* Return true if we use function descriptors. */
> +
> +static bool
> +rs6000_has_function_descriptors (void)
> +{
> + return DEFAULT_ABI == ABI_AIX;
> +}
> +
> /* Say whether a function is a candidate for sibcall handling or not. */
>
> static bool
> Index: gcc/testsuite/gcc.target/powerpc/pr64703.c
> ===================================================================
> --- gcc/testsuite/gcc.target/powerpc/pr64703.c (revision 0)
> +++ gcc/testsuite/gcc.target/powerpc/pr64703.c (working copy)
> @@ -0,0 +1,36 @@
> +/* { dg-do compile { target { powerpc*-*-* && lp64 } } } */
> +/* { dg-skip-if "" { powerpc*-*-darwin* } { "*" } { "" } } */
> +/* { dg-options "-O2 -mabi=elfv1" } */
> +/* { dg-final { scan-assembler "std .\*,112\\(1\\)" } } */
> +/* { dg-final { scan-assembler "std .\*,120\\(1\\)" } } */
> +/* { dg-final { scan-assembler "std .\*,128\\(1\\)" } } */
> +/* { dg-final { scan-assembler "addi .\*,1,112" } } */
> +
> +/* Testcase taken from glibc, powerpc64 dl-machine.h. */
> +
> +typedef struct {
> + unsigned long fd_func;
> + unsigned long fd_toc;
> + unsigned long fd_aux;
> +} Elf64_FuncDesc;
> +
> +extern unsigned long dl_hwcap;
> +
> +unsigned long
> +resolve_ifunc (unsigned long value, unsigned long adjust)
> +{
> + Elf64_FuncDesc opd;
> +
> + if (adjust)
> + {
> + Elf64_FuncDesc *func = (Elf64_FuncDesc *) value;
> + opd.fd_func = func->fd_func + adjust;
> + opd.fd_toc = func->fd_toc + adjust;
> + opd.fd_aux = func->fd_aux;
> + value = (unsigned long) &opd;
> + }
> +#if 0
> + __asm__ ("#%0" : : "r" (value));
> +#endif
> + return ((unsigned long (*) (unsigned long)) value) (dl_hwcap);
> +}
>
> --
> Alan Modra
> Australia Development Lab, IBM
