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Generate a label for the split cold function while using -freorder-blocks-and-partition

Message ID CAAs8HmxA8W9SVEGi59SvMhbL4vNa4rmOvWN=A9Wbn8_evNjfNg@mail.gmail.com
State New
Headers show

Commit Message

Sriraman Tallam April 25, 2013, 11:42 p.m. UTC 
On Tue, Apr 23, 2013 at 9:59 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Tue, Apr 23, 2013 at 03:58:06PM -0700, Sriraman Tallam wrote:
>>   This patch generates labels for cold function parts that are split when
>> using the option -freorder-blocks-and-partition.  The cold label name
>> is generated by suffixing ".cold" to the assembler name of the hot
>> function.
>>
>>   This is useful when getting back traces from gdb when the cold function
>> part does get executed.
>>
>>         * final.c (final_scan_insn): Generate cold label name by suffixing
>>         ".cold" to function's assembler name.
>>         * gcc.dg/tree-prof/cold_partition_label.c: New test.
>
> This doesn't honor NO_DOT_IN_LABEL (and NO_DOLLAR_IN_LABEL).

Fixed, by calling clean_symbol_name

> Also, don't some function start in cold section and then switch into hot
> section?

I am not able to generate a test where this happens. However, I  fixed
this problem by generating the cold label only when the first function
block is not cold.

Patch attached, please see if this is ok.

Thanks
Sri

>
>         Jakub
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Patch

Index: final.c
===================================================================
--- final.c	(revision 198212)
+++ final.c	(working copy)
@@ -2101,6 +2101,22 @@  final_scan_insn (rtx insn, FILE *file, int optimiz
 	  targetm.asm_out.function_switched_text_sections (asm_out_file,
 							   current_function_decl,
 							   in_cold_section_p);
+	  /* Emit a label for the split cold section.  Form label name by
+	     suffixing ".cold" to the function's assembler name.  */
+	  if (in_cold_section_p)
+	    {
+	      char *cold_function_name;
+	      const char *mangled_function_name;
+	      tree asm_name = DECL_ASSEMBLER_NAME (current_function_decl);
+
+	      mangled_function_name = IDENTIFIER_POINTER (asm_name);
+	      cold_function_name = XNEWVEC (char,
+	          strlen (mangled_function_name) + strlen (".cold") + 1);
+	      sprintf (cold_function_name, "%s.cold", mangled_function_name);
+	      clean_symbol_name (cold_function_name);
+	      ASM_OUTPUT_LABEL (asm_out_file, cold_function_name);
+	      XDELETEVEC (cold_function_name);
+	    }
 	  break;
 
 	case NOTE_INSN_BASIC_BLOCK:
Index: testsuite/gcc.dg/tree-prof/cold_partition_label.c
===================================================================
--- testsuite/gcc.dg/tree-prof/cold_partition_label.c	(revision 0)
+++ testsuite/gcc.dg/tree-prof/cold_partition_label.c	(revision 0)
@@ -0,0 +1,39 @@ 
+/* Test case to check if function foo gets split and the cold function
+   gets a label.  */
+/* { dg-require-effective-target freorder } */
+/* { dg-options "-O2 -freorder-blocks-and-partition --save-temps" } */
+
+#define SIZE 10000
+
+const char *sarr[SIZE];
+const char *buf_hot;
+const char *buf_cold;
+
+__attribute__((noinline))
+void 
+foo (int path)
+{
+  int i;
+  if (path)
+    {
+      for (i = 0; i < SIZE; i++)
+	sarr[i] = buf_hot;
+    }
+  else
+    {
+      for (i = 0; i < SIZE; i++)
+	sarr[i] = buf_cold;
+    }
+}
+
+int
+main (int argc, char *argv[])
+{
+  buf_hot =  "hello";
+  buf_cold = "world";
+  foo (argc);
+  return 0;
+}
+
+/* { dg-final-use { scan-assembler "foo\.cold" } } */
+/* { dg-final-use { cleanup-saved-temps } } */