Re: [nvptx] fix some c++ tests

[Bernd Schmidt]

On 10/09/2015 07:55 AM, Thomas Schwinge wrote:

Hi Nathan!

Thanks for looking into this.  When I reported this,
,
quite a lot of testcases had been failing -- with recent GCC trunk, the
number is smaller (because of other middle end/optimization changes, I
suppose).  Yet, the problem still can be observed; grep for "%retval" in
g++.log.

On Thu, 8 Oct 2015 13:33:55 -0400, Nathan Sidwell  wrote:

I've committed this to trunk.  The C++ ABI now returns a pointer to the
passed-in artificial arg that points to the return area.  consequently
return-in-mem and type_mode(return_type) == VOIDmode are  not tautologies.



* config/nvptx/nvptx.c (nvptx_declare_function_name): Functions
may return pointer as well as in memory.
(nvptx_output_return): Likewise.


Hmm, but what I now see happening is that now there is incorrect
"%out_retval" usage (but it's not part of the function prototypes), for
example:


Does the caller end up using that extra pointer? Otherwise, just reusing 
TARGET_OMIT_STRUCT_RETURN_REG might be useful.



Bernd

[nvptx] fix some c++ tests

[Nathan Sidwell]

I've committed this to trunk.  The C++ ABI now returns a pointer to the 
passed-in artificial arg that points to the return area.  consequently 
return-in-mem and type_mode(return_type) == VOIDmode are  not tautologies.


nathan
2015-10-08  Nathan Sidwell  

	* config/nvptx/nvptx.h (struct machine_function): Add comment.
	* config/nvptx/nvptx.c (nvptx_declare_function_name): Functions
	may return pointer as well as in memory.
	(nvptx_output_return): Likewise.

Index: gcc/config/nvptx/nvptx.c
===
--- gcc/config/nvptx/nvptx.c	(revision 228617)
+++ gcc/config/nvptx/nvptx.c	(working copy)
@@ -531,13 +531,8 @@ nvptx_declare_function_name (FILE *file,
   nvptx_write_function_decl (s, name, decl);
   fprintf (file, "%s", s.str().c_str());
 
-  bool return_in_mem = false;
-  if (TYPE_MODE (result_type) != VOIDmode)
-{
-  machine_mode mode = TYPE_MODE (result_type);
-  if (!RETURN_IN_REG_P (mode))
-	return_in_mem = true;
-}
+  bool return_in_mem = (TYPE_MODE (result_type) != VOIDmode
+			&& !RETURN_IN_REG_P (TYPE_MODE (result_type)));
 
   fprintf (file, "\n{\n");
 
@@ -547,9 +542,13 @@ nvptx_declare_function_name (FILE *file,
 		   false, return_in_mem);
   if (return_in_mem)
 fprintf (file, "\t.reg.u%d %%ar1;\n", GET_MODE_BITSIZE (Pmode));
-  else if (TYPE_MODE (result_type) != VOIDmode)
+
+  /* C++11 ABI causes us to return a reference to the passed in
+ pointer for return_in_mem.  */
+  if (cfun->machine->ret_reg_mode != VOIDmode)
 {
-  machine_mode mode = arg_promotion (TYPE_MODE (result_type));
+  machine_mode mode = arg_promotion
+	((machine_mode)cfun->machine->ret_reg_mode);
   fprintf (file, "\t.reg%s %%retval;\n",
 	   nvptx_ptx_type_from_mode (mode, false));
 }
@@ -635,17 +634,13 @@ nvptx_declare_function_name (FILE *file,
 const char *
 nvptx_output_return (void)
 {
-  tree fntype = TREE_TYPE (current_function_decl);
-  tree result_type = TREE_TYPE (fntype);
-  if (TYPE_MODE (result_type) != VOIDmode)
+  machine_mode mode = (machine_mode)cfun->machine->ret_reg_mode;
+
+  if (mode != VOIDmode)
 {
-  machine_mode mode = TYPE_MODE (result_type);
-  if (RETURN_IN_REG_P (mode))
-	{
-	  mode = arg_promotion (mode);
-	  fprintf (asm_out_file, "\tst.param%s\t[%%out_retval], %%retval;\n",
-		   nvptx_ptx_type_from_mode (mode, false));
-	}
+  mode = arg_promotion (mode);
+  fprintf (asm_out_file, "\tst.param%s\t[%%out_retval], %%retval;\n",
+	   nvptx_ptx_type_from_mode (mode, false));
 }
 
   return "ret;";
Index: gcc/config/nvptx/nvptx.h
===
--- gcc/config/nvptx/nvptx.h	(revision 228617)
+++ gcc/config/nvptx/nvptx.h	(working copy)
@@ -228,7 +228,7 @@ struct GTY(()) machine_function
   bool has_call_with_varargs;
   bool has_call_with_sc;
   HOST_WIDE_INT outgoing_stdarg_size;
-  int ret_reg_mode;
+  int ret_reg_mode; /* machine_mode not defined yet. */
   int punning_buffer_size;
 };
 #endif

Re: [nvptx] fix some c++ tests

[Thomas Schwinge]

Hi Nathan!

Thanks for looking into this.  When I reported this,
,
quite a lot of testcases had been failing -- with recent GCC trunk, the
number is smaller (because of other middle end/optimization changes, I
suppose).  Yet, the problem still can be observed; grep for "%retval" in
g++.log.

On Thu, 8 Oct 2015 13:33:55 -0400, Nathan Sidwell  wrote:
> I've committed this to trunk.  The C++ ABI now returns a pointer to the 
> passed-in artificial arg that points to the return area.  consequently 
> return-in-mem and type_mode(return_type) == VOIDmode are  not tautologies.

>   * config/nvptx/nvptx.c (nvptx_declare_function_name): Functions
>   may return pointer as well as in memory.
>   (nvptx_output_return): Likewise.

Hmm, but what I now see happening is that now there is incorrect
"%out_retval" usage (but it's not part of the function prototypes), for
example:

$ build-gcc/gcc/xg++ -Bbuild-gcc/gcc/ 
source-gcc/gcc/testsuite/g++.dg/ipa/ipa-icf-6.C -std=gnu++98 -O3 -o 
ipa-icf-6.exe -S

Diff before/after your change:

$ diff -U4 O/ipa-icf-6.exe ipa-icf-6.exe
--- O/ipa-icf-6.exe 2015-10-06 18:30:21.581187448 +0200
+++ ipa-icf-6.exe   2015-10-09 07:49:23.894893180 +0200
@@ -10,8 +10,9 @@
 .visible .func _Z5test21A(.param.u64 %in_ar1, .param.u64 %in_ar2)
 {
.reg.u64 %ar2;
.reg.u64 %ar1;
+   .reg.u64 %retval;
.reg.u64 %hr10;
.reg.u64 %r25;
.reg.u64 %r26;
.reg.u64 %r27;
@@ -28,8 +29,9 @@
}
 $L2:
st.u64  [%r25+8], %r25;
mov.u64 %retval, %r25;
+   st.param.u64[%out_retval], %retval;
ret;
}
 // BEGIN FUNCTION DECL: _ZL7test_mePF1AS_E
 .func _ZL7test_mePF1AS_E(.param.u64 %in_ar1);
@@ -78,8 +80,9 @@
 .visible .func _Z5test11A(.param.u64 %in_ar1, .param.u64 %in_ar2)
 {
.reg.u64 %ar2;
.reg.u64 %ar1;
+   .reg.u64 %retval;
.reg.u64 %hr10;
.reg.u64 %r25;
.reg.u64 %r26;
.reg.u64 %r27;
@@ -96,8 +99,9 @@
}
 $L6:
st.u64  [%r25+8], %r25;
mov.u64 %retval, %r25;
+   st.param.u64[%out_retval], %retval;
ret;
}
 // BEGIN GLOBAL FUNCTION DECL: main
 .visible .func (.param.u32 %out_retval)main(.param.u32 %argc, .param.u64 
%argv);

(I have not yet made an attempt at trying to understand the problem.)


For reference:

> Index: gcc/config/nvptx/nvptx.c
> ===
> --- gcc/config/nvptx/nvptx.c  (revision 228617)
> +++ gcc/config/nvptx/nvptx.c  (working copy)
> @@ -531,13 +531,8 @@ nvptx_declare_function_name (FILE *file,
>nvptx_write_function_decl (s, name, decl);
>fprintf (file, "%s", s.str().c_str());
>  
> -  bool return_in_mem = false;
> -  if (TYPE_MODE (result_type) != VOIDmode)
> -{
> -  machine_mode mode = TYPE_MODE (result_type);
> -  if (!RETURN_IN_REG_P (mode))
> - return_in_mem = true;
> -}
> +  bool return_in_mem = (TYPE_MODE (result_type) != VOIDmode
> + && !RETURN_IN_REG_P (TYPE_MODE (result_type)));
>  
>fprintf (file, "\n{\n");
>  
> @@ -547,9 +542,13 @@ nvptx_declare_function_name (FILE *file,
>  false, return_in_mem);
>if (return_in_mem)
>  fprintf (file, "\t.reg.u%d %%ar1;\n", GET_MODE_BITSIZE (Pmode));
> -  else if (TYPE_MODE (result_type) != VOIDmode)
> +
> +  /* C++11 ABI causes us to return a reference to the passed in
> + pointer for return_in_mem.  */
> +  if (cfun->machine->ret_reg_mode != VOIDmode)
>  {
> -  machine_mode mode = arg_promotion (TYPE_MODE (result_type));
> +  machine_mode mode = arg_promotion
> + ((machine_mode)cfun->machine->ret_reg_mode);
>fprintf (file, "\t.reg%s %%retval;\n",
>  nvptx_ptx_type_from_mode (mode, false));
>  }
> @@ -635,17 +634,13 @@ nvptx_declare_function_name (FILE *file,
>  const char *
>  nvptx_output_return (void)
>  {
> -  tree fntype = TREE_TYPE (current_function_decl);
> -  tree result_type = TREE_TYPE (fntype);
> -  if (TYPE_MODE (result_type) != VOIDmode)
> +  machine_mode mode = (machine_mode)cfun->machine->ret_reg_mode;
> +
> +  if (mode != VOIDmode)
>  {
> -  machine_mode mode = TYPE_MODE (result_type);
> -  if (RETURN_IN_REG_P (mode))
> - {
> -   mode = arg_promotion (mode);
> -   fprintf (asm_out_file, "\tst.param%s\t[%%out_retval], %%retval;\n",
> -nvptx_ptx_type_from_mode (mode, false));
> - }
> +  mode = arg_promotion (mode);
> +  fprintf (asm_out_file, "\tst.param%s\t[%%out_retval], %%retval;\n",
> +nvptx_ptx_type_from_mode (mode, false));
>  }
>  
>return "ret;";
> Index: gcc/config/nvptx/nvptx.h
> ===
> --- gcc/config/nvptx/nvptx.h