[PATCH][PR65818][bootstrap,hppa] Return side-effect free result in gimplify_va_arg_internal

[PATCH][PR65818][bootstrap,hppa] Return side-effect free result in gimplify_va_arg_internal

[Tom de Vries]

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Hi,

this patch fixes PR65818, and hppa bootstrap.

When compiling gcc/libiberty/vprintf-support.c, the following va_arg is compiled:
...
  (void) __builtin_va_arg(ap, double);
...

This results in the following ifn_va_arg at gimple level, with a NULL_TREE lhs:
...
   VA_ARG (&ap, 0B);
...

We start expanding the ifn_va_arg in expand_ifn_va_arg_1 by calling 
gimplify_va_arg_internal:
...
         expr = gimplify_va_arg_internal (ap, type, gimple_location (stmt),
                                          &pre, &post);
...

Subsequently, because the lhs is NULL_TREE, we skip generating the assign to the 
lhs:
...
	lhs = gimple_call_lhs (stmt);
	if (lhs != NULL_TREE)
	  {
	    gcc_assert (useless_type_conversion_p (TREE_TYPE (lhs), type));

	    if (gimple_call_num_args (stmt) == 3)
	      {
		/* We've transported the size of with WITH_SIZE_EXPR here as
		   the 3rd argument of the internal fn call.  Now reinstate
		   it.  */
		tree size = gimple_call_arg (stmt, 2);
		expr = build2 (WITH_SIZE_EXPR, TREE_TYPE (expr), expr, size);
	      }

	    /* We use gimplify_assign here, rather than gimple_build_assign,
	       because gimple_assign knows how to deal with variable-sized
	       types.  */
	    gimplify_assign (lhs, expr, &pre);
	  }
...

We assume here that any side-effects related to updating ap have been generated 
into pre/post by gimplify_va_arg_internal, and that it's safe to ignore expr.

Turns out, that's not the case for hppa. The target hook 
hppa_gimplify_va_arg_expr (called from gimplify_va_arg_internal) returns an 
expression that still contains a side-effect:
...
*(double *) (ap = ap + 4294967288 & 4294967288B)
...

This patch fixes that by gimplifying the address expression of the mem-ref 
returned by the target hook (borrowing code from gimplify_expr, case MEM_REF).

Bootstrapped and reg-tested on x86_64.

Bootstrapped and reg-tested on hppa2.0w-hp-hpux11.11.

OK for trunk?

Thanks,
- Tom


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Return side-effect free result in gimplify_va_arg_internal

2015-04-22  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/65818
	* gimplify.c (gimplify_va_arg_internal): Ensure that only side-effect
	free values are returned.
---
 gcc/gimplify.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index c68bd47..fe54e53 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -9352,7 +9352,12 @@ gimplify_va_arg_internal (tree valist, tree type, location_t loc,
   else
     gimplify_expr (&valist, pre_p, post_p, is_gimple_min_lval, fb_lvalue);
 
-  return targetm.gimplify_va_arg_expr (valist, type, pre_p, post_p);
+  tree expr = targetm.gimplify_va_arg_expr (valist, type, pre_p, post_p);
+  gcc_assert (TREE_CODE (expr) == MEM_REF);
+  if (!is_gimple_mem_ref_addr (TREE_OPERAND (expr, 0)))
+    gimplify_expr (&TREE_OPERAND (expr, 0), pre_p, post_p,
+		   is_gimple_mem_ref_addr, fb_rvalue);
+  return expr;
 }
 
 /* Gimplify __builtin_va_arg, aka VA_ARG_EXPR, which is not really a
-- 
1.9.1

Re: [PATCH][PR65818][bootstrap,hppa] Return side-effect free result in gimplify_va_arg_internal

[Richard Biener]

On Sat, Apr 25, 2015 at 2:35 PM, Tom de Vries <Tom_deVries@mentor.com> wrote:
> Hi,
>
> this patch fixes PR65818, and hppa bootstrap.
>
> When compiling gcc/libiberty/vprintf-support.c, the following va_arg is
> compiled:
> ...
>  (void) __builtin_va_arg(ap, double);
> ...
>
> This results in the following ifn_va_arg at gimple level, with a NULL_TREE
> lhs:
> ...
>   VA_ARG (&ap, 0B);
> ...
>
> We start expanding the ifn_va_arg in expand_ifn_va_arg_1 by calling
> gimplify_va_arg_internal:
> ...
>         expr = gimplify_va_arg_internal (ap, type, gimple_location (stmt),
>                                          &pre, &post);
> ...
>
> Subsequently, because the lhs is NULL_TREE, we skip generating the assign to
> the lhs:
> ...
>         lhs = gimple_call_lhs (stmt);
>         if (lhs != NULL_TREE)
>           {
>             gcc_assert (useless_type_conversion_p (TREE_TYPE (lhs), type));
>
>             if (gimple_call_num_args (stmt) == 3)
>               {
>                 /* We've transported the size of with WITH_SIZE_EXPR here as
>                    the 3rd argument of the internal fn call.  Now reinstate
>                    it.  */
>                 tree size = gimple_call_arg (stmt, 2);
>                 expr = build2 (WITH_SIZE_EXPR, TREE_TYPE (expr), expr,
> size);
>               }
>
>             /* We use gimplify_assign here, rather than gimple_build_assign,
>                because gimple_assign knows how to deal with variable-sized
>                types.  */
>             gimplify_assign (lhs, expr, &pre);
>           }
> ...
>
> We assume here that any side-effects related to updating ap have been
> generated into pre/post by gimplify_va_arg_internal, and that it's safe to
> ignore expr.
>
> Turns out, that's not the case for hppa. The target hook
> hppa_gimplify_va_arg_expr (called from gimplify_va_arg_internal) returns an
> expression that still contains a side-effect:
> ...
> *(double *) (ap = ap + 4294967288 & 4294967288B)
> ...
>
> This patch fixes that by gimplifying the address expression of the mem-ref
> returned by the target hook (borrowing code from gimplify_expr, case
> MEM_REF).
>
> Bootstrapped and reg-tested on x86_64.
>
> Bootstrapped and reg-tested on hppa2.0w-hp-hpux11.11.
>
> OK for trunk?

Hmm, that assert looks suspicious...

Can't you simply always do

  gimplify_expr (expr, pre_p, post_p, is_gimple_lvalue, fb_lvalue);

?

Richard.

> Thanks,
> - Tom
>

Re: [PATCH][PR65818][bootstrap,hppa] Return side-effect free result in gimplify_va_arg_internal

[Tom de Vries]

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On 27-04-15 10:17, Richard Biener wrote:
>> This patch fixes that by gimplifying the address expression of the mem-ref
>> >returned by the target hook (borrowing code from gimplify_expr, case
>> >MEM_REF).
>> >
>> >Bootstrapped and reg-tested on x86_64.
>> >
>> >Bootstrapped and reg-tested on hppa2.0w-hp-hpux11.11.
>> >
>> >OK for trunk?
> Hmm, that assert looks suspicious...
>
> Can't you simply always do
>
>    gimplify_expr (expr, pre_p, post_p, is_gimple_lvalue, fb_lvalue);

It's a bit counter-intuitive for me, using is_gimple_lvalue for something (the 
result of va_arg) we use as rvalue.

But, it seems to work (with & in front of expr).

OK if bootstrap and reg-test on x86_64 succeeds?

Thanks,
- Tom


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Return side-effect free result in gimplify_va_arg_internal

2015-04-27  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/65818
	* gimplify.c (gimplify_va_arg_internal): Ensure that only side-effect
	free values are returned.
---
 gcc/gimplify.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index c68bd47..4a68c87 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -9352,7 +9352,9 @@ gimplify_va_arg_internal (tree valist, tree type, location_t loc,
   else
     gimplify_expr (&valist, pre_p, post_p, is_gimple_min_lval, fb_lvalue);
 
-  return targetm.gimplify_va_arg_expr (valist, type, pre_p, post_p);
+  tree expr = targetm.gimplify_va_arg_expr (valist, type, pre_p, post_p);
+  gimplify_expr (&expr, pre_p, post_p, is_gimple_lvalue, fb_lvalue);
+  return expr;
 }
 
 /* Gimplify __builtin_va_arg, aka VA_ARG_EXPR, which is not really a
-- 
1.9.1

Re: [PATCH][PR65818][bootstrap,hppa] Return side-effect free result in gimplify_va_arg_internal

[Richard Biener]

On Mon, Apr 27, 2015 at 3:06 PM, Tom de Vries <Tom_deVries@mentor.com> wrote:
> On 27-04-15 10:17, Richard Biener wrote:
>>>
>>> This patch fixes that by gimplifying the address expression of the
>>> mem-ref
>>> >returned by the target hook (borrowing code from gimplify_expr, case
>>> >MEM_REF).
>>> >
>>> >Bootstrapped and reg-tested on x86_64.
>>> >
>>> >Bootstrapped and reg-tested on hppa2.0w-hp-hpux11.11.
>>> >
>>> >OK for trunk?
>>
>> Hmm, that assert looks suspicious...
>>
>> Can't you simply always do
>>
>>    gimplify_expr (expr, pre_p, post_p, is_gimple_lvalue, fb_lvalue);
>
>
> It's a bit counter-intuitive for me, using is_gimple_lvalue for something
> (the result of va_arg) we use as rvalue.

Yeah, choosing that was done because you could assert it's a MEM_REF
and tree-stdarg eventually builds a WITH_SIZE_EXPR around it.

It would possibly be easier to simply "inline" gimplify_va_arg_internal
at its use and only gimplify the assignment.  Though in that case the
original code probably worked - just in the lhs == NULL case it didn't,
which hints at a better place for the fix - in expand_ifn_va_arg_1 do

 if (lhs != NULL_TREE)
   {
...
   }
 else
   gimplify_expr (&expr, &pre, &post, is_gimple_val, fb_either);

So ... if you can re-try that one it's pre-approved.

Thanks,
Richard.

> But, it seems to work (with & in front of expr).
>
> OK if bootstrap and reg-test on x86_64 succeeds?
>
> Thanks,
> - Tom
>

Re: [PATCH][PR65818][bootstrap,hppa] Return side-effect free result in gimplify_va_arg_internal

[Tom de Vries]

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On 27-04-15 15:40, Richard Biener wrote:
> On Mon, Apr 27, 2015 at 3:06 PM, Tom de Vries <Tom_deVries@mentor.com> wrote:
>> On 27-04-15 10:17, Richard Biener wrote:
>>>>
>>>> This patch fixes that by gimplifying the address expression of the
>>>> mem-ref
>>>>> returned by the target hook (borrowing code from gimplify_expr, case
>>>>> MEM_REF).
>>>>>
>>>>> Bootstrapped and reg-tested on x86_64.
>>>>>
>>>>> Bootstrapped and reg-tested on hppa2.0w-hp-hpux11.11.
>>>>>
>>>>> OK for trunk?
>>>
>>> Hmm, that assert looks suspicious...
>>>
>>> Can't you simply always do
>>>
>>>     gimplify_expr (expr, pre_p, post_p, is_gimple_lvalue, fb_lvalue);
>>
>>
>> It's a bit counter-intuitive for me, using is_gimple_lvalue for something
>> (the result of va_arg) we use as rvalue.
>
> Yeah, choosing that was done because you could assert it's a MEM_REF
> and tree-stdarg eventually builds a WITH_SIZE_EXPR around it.
>
> It would possibly be easier to simply "inline" gimplify_va_arg_internal
> at its use and only gimplify the assignment.  Though in that case the
> original code probably worked - just in the lhs == NULL case it didn't,
> which hints at a better place for the fix - in expand_ifn_va_arg_1 do
>
>   if (lhs != NULL_TREE)
>     {
> ...
>     }
>   else
>     gimplify_expr (&expr, &pre, &post, is_gimple_val, fb_either);
>
> So ... if you can re-try that one it's pre-approved.
>

Using that proposed patch, we run into the following problem.

Consider this testcase with ignored-result-va_arg:
...
#include <stdarg.h>

void
f2 (int i, ...)
{
   va_list ap;
   va_start (ap, i);
   va_arg (ap, long);
   va_end (ap);
}
...

after gimplify_va_arg_internal we have:
...
(gdb) call debug_generic_expr (expr)
*(long int * {ref-all}) addr.2
...

In a bit more detail:
...
(gdb) call debug_tree (expr)
  <mem_ref 0x7ffff65ea1b8
     type <integer_type 0x7ffff64a77e0 long int DI
         size <integer_cst 0x7ffff64a3ca8 constant 64>
         unit size <integer_cst 0x7ffff64a3cc0 constant 8>
         align 64 symtab 0 alias set -1 canonical type 0x7ffff64a77e0 precision 
64 min <integer_cst 0x7ffff64a3f30 -9223372036854775808> max <integer_cst 
0x7ffff64a3f48 9223372036854775807>
         pointer_to_this <pointer_type 0x7ffff65e0498>>

     arg 0 <nop_expr 0x7ffff65cbb60
         type <pointer_type 0x7ffff65e0498 type <integer_type 0x7ffff64a77e0 
long int>
             public static unsigned DI size <integer_cst 0x7ffff64a3ca8 64> unit 
size <integer_cst 0x7ffff64a3cc0 8>
             align 64 symtab 0 alias set -1 canonical type 0x7ffff65e0498>

         arg 0 <var_decl 0x7ffff65e32d0 addr.2 type <pointer_type 0x7ffff64c2150>
             used unsigned ignored DI file stdarg-1.c line 4 col 1 size 
<integer_cst 0x7ffff64a3ca8 64> unit size <integer_cst 0x7ffff64a3cc0 8>
             align 64 context <function_decl 0x7ffff65c21b0 f2>>>
     arg 1 <integer_cst 0x7ffff65e64e0 type <pointer_type 0x7ffff65e0498> 
constant 0>>
...

During 'gimplify_expr (&expr, &pre, &post, is_gimple_val, fb_either)' we ICE here:
...
8886	  gcc_assert ((*gimple_test_f) (*expr_p));
...

At this point expr is:
...
(gdb) call debug_generic_expr (*expr_p)
*addr.2
...

In more detail:
...
(gdb) call debug_tree (*expr_p)
  <mem_ref 0x7ffff65ea1e0
     type <void_type 0x7ffff64c2000 void VOID
         align 8 symtab 0 alias set -1 canonical type 0x7ffff64c2000
         pointer_to_this <pointer_type 0x7ffff64c2150>>

     arg 0 <var_decl 0x7ffff65e32d0 addr.2
         type <pointer_type 0x7ffff64c2150 type <void_type 0x7ffff64c2000 void>
             sizes-gimplified public unsigned DI
             size <integer_cst 0x7ffff64a3ca8 constant 64>
             unit size <integer_cst 0x7ffff64a3cc0 constant 8>
             align 64 symtab 0 alias set -1 canonical type 0x7ffff64c2150
             pointer_to_this <pointer_type 0x7ffff64c9bd0>>
         used unsigned ignored DI file stdarg-1.c line 4 col 1 size <integer_cst 
0x7ffff64a3ca8 64> unit size <integer_cst 0x7ffff64a3cc0 8>
         align 64 context <function_decl 0x7ffff65c21b0 f2>>
     arg 1 <integer_cst 0x7ffff64c10c0 type <pointer_type 0x7ffff64c2150> 
constant 0>>
...

The memref is now VOID type. And that's not a gimple_val:
...
(gdb) p is_gimple_val (*expr_p)
$1 = false
...

Attached patch uses is_gimple_lvalue, but in expand_ifn_va_arg_1.

I'll bootstrap and reg-test on x86_64 and commit, unless further comments of course.

Thanks,
- Tom

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Evaluate side-effects in expand_ifn_va_arg_1

2015-04-27  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/65818
	* tree-stdarg.c (expand_ifn_va_arg_1): Ensure that side-effects are
	evaluated.
---
 gcc/tree-stdarg.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/gcc/tree-stdarg.c b/gcc/tree-stdarg.c
index 16a9e2c..1356374 100644
--- a/gcc/tree-stdarg.c
+++ b/gcc/tree-stdarg.c
@@ -1078,6 +1078,8 @@ expand_ifn_va_arg_1 (function *fun)
 	       types.  */
 	    gimplify_assign (lhs, expr, &pre);
 	  }
+	else
+	  gimplify_expr (&expr, &pre, &post, is_gimple_lvalue, fb_lvalue);
 
 	pop_gimplify_context (NULL);
 
-- 
1.9.1

Re: [PATCH][PR65818][bootstrap,hppa] Return side-effect free result in gimplify_va_arg_internal

[Richard Biener]

On Mon, Apr 27, 2015 at 5:04 PM, Tom de Vries <Tom_deVries@mentor.com> wrote:
> On 27-04-15 15:40, Richard Biener wrote:
>>
>> On Mon, Apr 27, 2015 at 3:06 PM, Tom de Vries <Tom_deVries@mentor.com>
>> wrote:
>>>
>>> On 27-04-15 10:17, Richard Biener wrote:
>>>>>
>>>>>
>>>>> This patch fixes that by gimplifying the address expression of the
>>>>> mem-ref
>>>>>>
>>>>>> returned by the target hook (borrowing code from gimplify_expr, case
>>>>>> MEM_REF).
>>>>>>
>>>>>> Bootstrapped and reg-tested on x86_64.
>>>>>>
>>>>>> Bootstrapped and reg-tested on hppa2.0w-hp-hpux11.11.
>>>>>>
>>>>>> OK for trunk?
>>>>
>>>>
>>>> Hmm, that assert looks suspicious...
>>>>
>>>> Can't you simply always do
>>>>
>>>>     gimplify_expr (expr, pre_p, post_p, is_gimple_lvalue, fb_lvalue);
>>>
>>>
>>>
>>> It's a bit counter-intuitive for me, using is_gimple_lvalue for something
>>> (the result of va_arg) we use as rvalue.
>>
>>
>> Yeah, choosing that was done because you could assert it's a MEM_REF
>> and tree-stdarg eventually builds a WITH_SIZE_EXPR around it.
>>
>> It would possibly be easier to simply "inline" gimplify_va_arg_internal
>> at its use and only gimplify the assignment.  Though in that case the
>> original code probably worked - just in the lhs == NULL case it didn't,
>> which hints at a better place for the fix - in expand_ifn_va_arg_1 do
>>
>>   if (lhs != NULL_TREE)
>>     {
>> ...
>>     }
>>   else
>>     gimplify_expr (&expr, &pre, &post, is_gimple_val, fb_either);
>>
>> So ... if you can re-try that one it's pre-approved.
>>
>
> Using that proposed patch, we run into the following problem.
>
> Consider this testcase with ignored-result-va_arg:
> ...
> #include <stdarg.h>
>
> void
> f2 (int i, ...)
> {
>   va_list ap;
>   va_start (ap, i);
>   va_arg (ap, long);
>   va_end (ap);
> }
> ...
>
> after gimplify_va_arg_internal we have:
> ...
> (gdb) call debug_generic_expr (expr)
> *(long int * {ref-all}) addr.2
> ...
>
> In a bit more detail:
> ...
> (gdb) call debug_tree (expr)
>  <mem_ref 0x7ffff65ea1b8
>     type <integer_type 0x7ffff64a77e0 long int DI
>         size <integer_cst 0x7ffff64a3ca8 constant 64>
>         unit size <integer_cst 0x7ffff64a3cc0 constant 8>
>         align 64 symtab 0 alias set -1 canonical type 0x7ffff64a77e0
> precision 64 min <integer_cst 0x7ffff64a3f30 -9223372036854775808> max
> <integer_cst 0x7ffff64a3f48 9223372036854775807>
>         pointer_to_this <pointer_type 0x7ffff65e0498>>
>
>     arg 0 <nop_expr 0x7ffff65cbb60
>         type <pointer_type 0x7ffff65e0498 type <integer_type 0x7ffff64a77e0
> long int>
>             public static unsigned DI size <integer_cst 0x7ffff64a3ca8 64>
> unit size <integer_cst 0x7ffff64a3cc0 8>
>             align 64 symtab 0 alias set -1 canonical type 0x7ffff65e0498>
>
>         arg 0 <var_decl 0x7ffff65e32d0 addr.2 type <pointer_type
> 0x7ffff64c2150>
>             used unsigned ignored DI file stdarg-1.c line 4 col 1 size
> <integer_cst 0x7ffff64a3ca8 64> unit size <integer_cst 0x7ffff64a3cc0 8>
>             align 64 context <function_decl 0x7ffff65c21b0 f2>>>
>     arg 1 <integer_cst 0x7ffff65e64e0 type <pointer_type 0x7ffff65e0498>
> constant 0>>
> ...
>
> During 'gimplify_expr (&expr, &pre, &post, is_gimple_val, fb_either)' we ICE
> here:
> ...
> 8886      gcc_assert ((*gimple_test_f) (*expr_p));
> ...
>
> At this point expr is:
> ...
> (gdb) call debug_generic_expr (*expr_p)
> *addr.2
> ...
>
> In more detail:
> ...
> (gdb) call debug_tree (*expr_p)
>  <mem_ref 0x7ffff65ea1e0
>     type <void_type 0x7ffff64c2000 void VOID
>         align 8 symtab 0 alias set -1 canonical type 0x7ffff64c2000
>         pointer_to_this <pointer_type 0x7ffff64c2150>>
>
>     arg 0 <var_decl 0x7ffff65e32d0 addr.2
>         type <pointer_type 0x7ffff64c2150 type <void_type 0x7ffff64c2000
> void>
>             sizes-gimplified public unsigned DI
>             size <integer_cst 0x7ffff64a3ca8 constant 64>
>             unit size <integer_cst 0x7ffff64a3cc0 constant 8>
>             align 64 symtab 0 alias set -1 canonical type 0x7ffff64c2150
>             pointer_to_this <pointer_type 0x7ffff64c9bd0>>
>         used unsigned ignored DI file stdarg-1.c line 4 col 1 size
> <integer_cst 0x7ffff64a3ca8 64> unit size <integer_cst 0x7ffff64a3cc0 8>
>         align 64 context <function_decl 0x7ffff65c21b0 f2>>
>     arg 1 <integer_cst 0x7ffff64c10c0 type <pointer_type 0x7ffff64c2150>
> constant 0>>
> ...
>
> The memref is now VOID type. And that's not a gimple_val:
> ...
> (gdb) p is_gimple_val (*expr_p)
> $1 = false
> ...

On which target?  I can't seem to reproduce on x86_64 or i?86.  I also
can't see how this
could happen.

Richard.

> Attached patch uses is_gimple_lvalue, but in expand_ifn_va_arg_1.
>
> I'll bootstrap and reg-test on x86_64 and commit, unless further comments of
> course.
>
> Thanks,
> - Tom

Re: [PATCH][PR65818][bootstrap,hppa] Return side-effect free result in gimplify_va_arg_internal

[Tom de Vries]

[-- Attachment #1: Type: text/plain, Size: 5191 bytes --]

On 28-04-15 12:34, Richard Biener wrote:
> On Mon, Apr 27, 2015 at 5:04 PM, Tom de Vries <Tom_deVries@mentor.com> wrote:
>> On 27-04-15 15:40, Richard Biener wrote:
>>>
>>> On Mon, Apr 27, 2015 at 3:06 PM, Tom de Vries <Tom_deVries@mentor.com>
>>> wrote:
>>>>
>>>> On 27-04-15 10:17, Richard Biener wrote:
>>>>>>
>>>>>>
>>>>>> This patch fixes that by gimplifying the address expression of the
>>>>>> mem-ref
>>>>>>>
>>>>>>> returned by the target hook (borrowing code from gimplify_expr, case
>>>>>>> MEM_REF).
>>>>>>>
>>>>>>> Bootstrapped and reg-tested on x86_64.
>>>>>>>
>>>>>>> Bootstrapped and reg-tested on hppa2.0w-hp-hpux11.11.
>>>>>>>
>>>>>>> OK for trunk?
>>>>>
>>>>>
>>>>> Hmm, that assert looks suspicious...
>>>>>
>>>>> Can't you simply always do
>>>>>
>>>>>      gimplify_expr (expr, pre_p, post_p, is_gimple_lvalue, fb_lvalue);
>>>>
>>>>
>>>>
>>>> It's a bit counter-intuitive for me, using is_gimple_lvalue for something
>>>> (the result of va_arg) we use as rvalue.
>>>
>>>
>>> Yeah, choosing that was done because you could assert it's a MEM_REF
>>> and tree-stdarg eventually builds a WITH_SIZE_EXPR around it.
>>>
>>> It would possibly be easier to simply "inline" gimplify_va_arg_internal
>>> at its use and only gimplify the assignment.  Though in that case the
>>> original code probably worked - just in the lhs == NULL case it didn't,
>>> which hints at a better place for the fix - in expand_ifn_va_arg_1 do
>>>
>>>    if (lhs != NULL_TREE)
>>>      {
>>> ...
>>>      }
>>>    else
>>>      gimplify_expr (&expr, &pre, &post, is_gimple_val, fb_either);
>>>
>>> So ... if you can re-try that one it's pre-approved.
>>>
>>
>> Using that proposed patch, we run into the following problem.
>>
>> Consider this testcase with ignored-result-va_arg:
>> ...
>> #include <stdarg.h>
>>
>> void
>> f2 (int i, ...)
>> {
>>    va_list ap;
>>    va_start (ap, i);
>>    va_arg (ap, long);
>>    va_end (ap);
>> }
>> ...
>>
>> after gimplify_va_arg_internal we have:
>> ...
>> (gdb) call debug_generic_expr (expr)
>> *(long int * {ref-all}) addr.2
>> ...
>>
>> In a bit more detail:
>> ...
>> (gdb) call debug_tree (expr)
>>   <mem_ref 0x7ffff65ea1b8
>>      type <integer_type 0x7ffff64a77e0 long int DI
>>          size <integer_cst 0x7ffff64a3ca8 constant 64>
>>          unit size <integer_cst 0x7ffff64a3cc0 constant 8>
>>          align 64 symtab 0 alias set -1 canonical type 0x7ffff64a77e0
>> precision 64 min <integer_cst 0x7ffff64a3f30 -9223372036854775808> max
>> <integer_cst 0x7ffff64a3f48 9223372036854775807>
>>          pointer_to_this <pointer_type 0x7ffff65e0498>>
>>
>>      arg 0 <nop_expr 0x7ffff65cbb60
>>          type <pointer_type 0x7ffff65e0498 type <integer_type 0x7ffff64a77e0
>> long int>
>>              public static unsigned DI size <integer_cst 0x7ffff64a3ca8 64>
>> unit size <integer_cst 0x7ffff64a3cc0 8>
>>              align 64 symtab 0 alias set -1 canonical type 0x7ffff65e0498>
>>
>>          arg 0 <var_decl 0x7ffff65e32d0 addr.2 type <pointer_type
>> 0x7ffff64c2150>
>>              used unsigned ignored DI file stdarg-1.c line 4 col 1 size
>> <integer_cst 0x7ffff64a3ca8 64> unit size <integer_cst 0x7ffff64a3cc0 8>
>>              align 64 context <function_decl 0x7ffff65c21b0 f2>>>
>>      arg 1 <integer_cst 0x7ffff65e64e0 type <pointer_type 0x7ffff65e0498>
>> constant 0>>
>> ...
>>
>> During 'gimplify_expr (&expr, &pre, &post, is_gimple_val, fb_either)' we ICE
>> here:
>> ...
>> 8886      gcc_assert ((*gimple_test_f) (*expr_p));
>> ...
>>
>> At this point expr is:
>> ...
>> (gdb) call debug_generic_expr (*expr_p)
>> *addr.2
>> ...
>>
>> In more detail:
>> ...
>> (gdb) call debug_tree (*expr_p)
>>   <mem_ref 0x7ffff65ea1e0
>>      type <void_type 0x7ffff64c2000 void VOID
>>          align 8 symtab 0 alias set -1 canonical type 0x7ffff64c2000
>>          pointer_to_this <pointer_type 0x7ffff64c2150>>
>>
>>      arg 0 <var_decl 0x7ffff65e32d0 addr.2
>>          type <pointer_type 0x7ffff64c2150 type <void_type 0x7ffff64c2000
>> void>
>>              sizes-gimplified public unsigned DI
>>              size <integer_cst 0x7ffff64a3ca8 constant 64>
>>              unit size <integer_cst 0x7ffff64a3cc0 constant 8>
>>              align 64 symtab 0 alias set -1 canonical type 0x7ffff64c2150
>>              pointer_to_this <pointer_type 0x7ffff64c9bd0>>
>>          used unsigned ignored DI file stdarg-1.c line 4 col 1 size
>> <integer_cst 0x7ffff64a3ca8 64> unit size <integer_cst 0x7ffff64a3cc0 8>
>>          align 64 context <function_decl 0x7ffff65c21b0 f2>>
>>      arg 1 <integer_cst 0x7ffff64c10c0 type <pointer_type 0x7ffff64c2150>
>> constant 0>>
>> ...
>>
>> The memref is now VOID type. And that's not a gimple_val:
>> ...
>> (gdb) p is_gimple_val (*expr_p)
>> $1 = false
>> ...
>
> On which target?  I can't seem to reproduce on x86_64 or i?86.  I also
> can't see how this
> could happen.
>

Reproduced using attached patch on top of r222537, for target x86_64, with and 
without -m32.

Thanks,
- Tom

> Richard.
>
>> Attached patch uses is_gimple_lvalue, but in expand_ifn_va_arg_1.
>>
>> I'll bootstrap and reg-test on x86_64 and commit, unless further comments of
>> course.
>>
>> Thanks,
>> - Tom


[-- Attachment #2: 0001-Reproduce-ICE-in-gimplify_expr-gcc_assert-gimple_tes.patch --]
[-- Type: text/x-patch, Size: 875 bytes --]

Reproduce ICE in 'gimplify_expr:
  gcc_assert ((*gimple_test_f) (*expr_p))'

diff --git a/gcc/testsuite/gcc.dg/reproduce.c b/gcc/testsuite/gcc.dg/reproduce.c
new file mode 100644
index 0000000..c0c8e0b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/reproduce.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+#include <stdarg.h>
+
+void
+f2 (int i, ...)
+{
+  va_list ap;
+  va_start (ap, i);
+  va_arg (ap, long);
+  va_end (ap);
+}
diff --git a/gcc/tree-stdarg.c b/gcc/tree-stdarg.c
index 1356374..829cbc1 100644
--- a/gcc/tree-stdarg.c
+++ b/gcc/tree-stdarg.c
@@ -1079,7 +1079,7 @@ expand_ifn_va_arg_1 (function *fun)
 	    gimplify_assign (lhs, expr, &pre);
 	  }
 	else
-	  gimplify_expr (&expr, &pre, &post, is_gimple_lvalue, fb_lvalue);
+	  gimplify_expr (&expr, &pre, &post, is_gimple_val, fb_either);
 
 	pop_gimplify_context (NULL);
 
-- 
1.9.1

Re: [PATCH][PR65818][bootstrap,hppa] Return side-effect free result in gimplify_va_arg_internal

[Richard Biener]

On Tue, Apr 28, 2015 at 10:29 PM, Tom de Vries <Tom_deVries@mentor.com> wrote:
> On 28-04-15 12:34, Richard Biener wrote:
>>
>> On Mon, Apr 27, 2015 at 5:04 PM, Tom de Vries <Tom_deVries@mentor.com>
>> wrote:
>>>
>>> On 27-04-15 15:40, Richard Biener wrote:
>>>>
>>>>
>>>> On Mon, Apr 27, 2015 at 3:06 PM, Tom de Vries <Tom_deVries@mentor.com>
>>>> wrote:
>>>>>
>>>>>
>>>>> On 27-04-15 10:17, Richard Biener wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> This patch fixes that by gimplifying the address expression of the
>>>>>>> mem-ref
>>>>>>>>
>>>>>>>>
>>>>>>>> returned by the target hook (borrowing code from gimplify_expr, case
>>>>>>>> MEM_REF).
>>>>>>>>
>>>>>>>> Bootstrapped and reg-tested on x86_64.
>>>>>>>>
>>>>>>>> Bootstrapped and reg-tested on hppa2.0w-hp-hpux11.11.
>>>>>>>>
>>>>>>>> OK for trunk?
>>>>>>
>>>>>>
>>>>>>
>>>>>> Hmm, that assert looks suspicious...
>>>>>>
>>>>>> Can't you simply always do
>>>>>>
>>>>>>      gimplify_expr (expr, pre_p, post_p, is_gimple_lvalue, fb_lvalue);
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> It's a bit counter-intuitive for me, using is_gimple_lvalue for
>>>>> something
>>>>> (the result of va_arg) we use as rvalue.
>>>>
>>>>
>>>>
>>>> Yeah, choosing that was done because you could assert it's a MEM_REF
>>>> and tree-stdarg eventually builds a WITH_SIZE_EXPR around it.
>>>>
>>>> It would possibly be easier to simply "inline" gimplify_va_arg_internal
>>>> at its use and only gimplify the assignment.  Though in that case the
>>>> original code probably worked - just in the lhs == NULL case it didn't,
>>>> which hints at a better place for the fix - in expand_ifn_va_arg_1 do
>>>>
>>>>    if (lhs != NULL_TREE)
>>>>      {
>>>> ...
>>>>      }
>>>>    else
>>>>      gimplify_expr (&expr, &pre, &post, is_gimple_val, fb_either);
>>>>
>>>> So ... if you can re-try that one it's pre-approved.
>>>>
>>>
>>> Using that proposed patch, we run into the following problem.
>>>
>>> Consider this testcase with ignored-result-va_arg:
>>> ...
>>> #include <stdarg.h>
>>>
>>> void
>>> f2 (int i, ...)
>>> {
>>>    va_list ap;
>>>    va_start (ap, i);
>>>    va_arg (ap, long);
>>>    va_end (ap);
>>> }
>>> ...
>>>
>>> after gimplify_va_arg_internal we have:
>>> ...
>>> (gdb) call debug_generic_expr (expr)
>>> *(long int * {ref-all}) addr.2
>>> ...
>>>
>>> In a bit more detail:
>>> ...
>>> (gdb) call debug_tree (expr)
>>>   <mem_ref 0x7ffff65ea1b8
>>>      type <integer_type 0x7ffff64a77e0 long int DI
>>>          size <integer_cst 0x7ffff64a3ca8 constant 64>
>>>          unit size <integer_cst 0x7ffff64a3cc0 constant 8>
>>>          align 64 symtab 0 alias set -1 canonical type 0x7ffff64a77e0
>>> precision 64 min <integer_cst 0x7ffff64a3f30 -9223372036854775808> max
>>> <integer_cst 0x7ffff64a3f48 9223372036854775807>
>>>          pointer_to_this <pointer_type 0x7ffff65e0498>>
>>>
>>>      arg 0 <nop_expr 0x7ffff65cbb60
>>>          type <pointer_type 0x7ffff65e0498 type <integer_type
>>> 0x7ffff64a77e0
>>> long int>
>>>              public static unsigned DI size <integer_cst 0x7ffff64a3ca8
>>> 64>
>>> unit size <integer_cst 0x7ffff64a3cc0 8>
>>>              align 64 symtab 0 alias set -1 canonical type
>>> 0x7ffff65e0498>
>>>
>>>          arg 0 <var_decl 0x7ffff65e32d0 addr.2 type <pointer_type
>>> 0x7ffff64c2150>
>>>              used unsigned ignored DI file stdarg-1.c line 4 col 1 size
>>> <integer_cst 0x7ffff64a3ca8 64> unit size <integer_cst 0x7ffff64a3cc0 8>
>>>              align 64 context <function_decl 0x7ffff65c21b0 f2>>>
>>>      arg 1 <integer_cst 0x7ffff65e64e0 type <pointer_type 0x7ffff65e0498>
>>> constant 0>>
>>> ...
>>>
>>> During 'gimplify_expr (&expr, &pre, &post, is_gimple_val, fb_either)' we
>>> ICE
>>> here:
>>> ...
>>> 8886      gcc_assert ((*gimple_test_f) (*expr_p));
>>> ...
>>>
>>> At this point expr is:
>>> ...
>>> (gdb) call debug_generic_expr (*expr_p)
>>> *addr.2
>>> ...
>>>
>>> In more detail:
>>> ...
>>> (gdb) call debug_tree (*expr_p)
>>>   <mem_ref 0x7ffff65ea1e0
>>>      type <void_type 0x7ffff64c2000 void VOID
>>>          align 8 symtab 0 alias set -1 canonical type 0x7ffff64c2000
>>>          pointer_to_this <pointer_type 0x7ffff64c2150>>
>>>
>>>      arg 0 <var_decl 0x7ffff65e32d0 addr.2
>>>          type <pointer_type 0x7ffff64c2150 type <void_type 0x7ffff64c2000
>>> void>
>>>              sizes-gimplified public unsigned DI
>>>              size <integer_cst 0x7ffff64a3ca8 constant 64>
>>>              unit size <integer_cst 0x7ffff64a3cc0 constant 8>
>>>              align 64 symtab 0 alias set -1 canonical type 0x7ffff64c2150
>>>              pointer_to_this <pointer_type 0x7ffff64c9bd0>>
>>>          used unsigned ignored DI file stdarg-1.c line 4 col 1 size
>>> <integer_cst 0x7ffff64a3ca8 64> unit size <integer_cst 0x7ffff64a3cc0 8>
>>>          align 64 context <function_decl 0x7ffff65c21b0 f2>>
>>>      arg 1 <integer_cst 0x7ffff64c10c0 type <pointer_type 0x7ffff64c2150>
>>> constant 0>>
>>> ...
>>>
>>> The memref is now VOID type. And that's not a gimple_val:
>>> ...
>>> (gdb) p is_gimple_val (*expr_p)
>>> $1 = false
>>> ...
>>
>>
>> On which target?  I can't seem to reproduce on x86_64 or i?86.  I also
>> can't see how this
>> could happen.
>>
>
> Reproduced using attached patch on top of r222537, for target x86_64, with
> and without -m32.

Ok, I see now.  The gimplifier seems to be confused with fb_lvalue.
all is_gimple_addressable ()s are already is_gimple_lvalue so

Index: gcc/gimplify.c
===================================================================
--- gcc/gimplify.c      (revision 222537)
+++ gcc/gimplify.c      (working copy)
@@ -8844,15 +8844,9 @@ gimplify_expr (tree *expr_p, gimple_seq
      rvalue.  */
   if ((fallback & fb_lvalue)
       && gimple_seq_empty_p (internal_post)
-      && is_gimple_addressable (*expr_p))
-    {
-      /* An lvalue will do.  Take the address of the expression, store it
-        in a temporary, and replace the expression with an INDIRECT_REF of
-        that temporary.  */
-      tmp = build_fold_addr_expr_loc (input_location, *expr_p);
-      gimplify_expr (&tmp, pre_p, post_p, is_gimple_reg, fb_rvalue);
-      *expr_p = build_simple_mem_ref (tmp);
-    }
+      && is_gimple_lvalue (*expr_p))
+    /* An lvalue will do and we already have one.  */
+    ;
   else if ((fallback & fb_rvalue) && is_gimple_reg_rhs_or_call (*expr_p))
     {
       /* An rvalue will do.  Assign the gimplified expression into a

should be enough for that case.  OTOH is_gimple_val will not be true
after this, so we'd still ICE later.  Which means fb_lvalue doesn't make
sense for is_gimple_val.

So your patch looks ok.

Richard.

> Thanks,
> - Tom
>
>
>> Richard.
>>
>>> Attached patch uses is_gimple_lvalue, but in expand_ifn_va_arg_1.
>>>
>>> I'll bootstrap and reg-test on x86_64 and commit, unless further comments
>>> of
>>> course.
>>>
>>> Thanks,
>>> - Tom
>
>