Re: -fuse-caller-save - Collect register usage information

[Tom de Vries]

On 19-06-14 07:13, Richard Henderson wrote:
On 05/19/2014 07:30 AM, Tom de Vries wrote:
>+  for (insn = get_insns (); insn != NULL_RTX; insn = next_insn (insn))
>+    {
>+      HARD_REG_SET insn_used_regs;
>+
>+      if (!NONDEBUG_INSN_P (insn))
>+   continue;
>+
>+      find_all_hard_reg_sets (insn, &insn_used_regs, false);
>+
>+      if (CALL_P (insn)
>+     && !get_call_reg_set_usage (insn, &insn_used_regs, call_used_reg_set))
>+   {
>+     CLEAR_HARD_REG_SET (node->function_used_regs);
>+     return;
>+   }
>+
>+      IOR_HARD_REG_SET (node->function_used_regs, insn_used_regs);
>+    }
As an aside, wouldn't it work out better if we collect into a local variable
instead of writing to memory here in node->function_used_regs each time?

Richard,

Agreed. This patch implements that. I'll bootstrap and reg-test on x86_64 and 
commit as obvious.

Thanks,
- Tom


2014-06-19  Tom de Vries  <t...@codesourcery.com>

	* final.c (collect_fn_hard_reg_usage): Add and use variable
	function_used_regs.

diff --git a/gcc/final.c b/gcc/final.c
index 4f08073..e39930d 100644
--- a/gcc/final.c
+++ b/gcc/final.c
@@ -4760,13 +4760,13 @@ collect_fn_hard_reg_usage (void)
   int i;
 #endif
   struct cgraph_rtl_info *node;
+  HARD_REG_SET function_used_regs;
 
   /* ??? To be removed when all the ports have been fixed.  */
   if (!targetm.call_fusage_contains_non_callee_clobbers)
     return;
 
-  node = cgraph_rtl_info (current_function_decl);
-  gcc_assert (node != NULL);
+  CLEAR_HARD_REG_SET (function_used_regs);
 
   for (insn = get_insns (); insn != NULL_RTX; insn = next_insn (insn))
     {
@@ -4779,25 +4779,26 @@ collect_fn_hard_reg_usage (void)
 
       if (CALL_P (insn)
 	  && !get_call_reg_set_usage (insn, &insn_used_regs, call_used_reg_set))
-	{
-	  CLEAR_HARD_REG_SET (node->function_used_regs);
-	  return;
-	}
+	return;
 
-      IOR_HARD_REG_SET (node->function_used_regs, insn_used_regs);
+      IOR_HARD_REG_SET (function_used_regs, insn_used_regs);
     }
 
   /* Be conservative - mark fixed and global registers as used.  */
-  IOR_HARD_REG_SET (node->function_used_regs, fixed_reg_set);
+  IOR_HARD_REG_SET (function_used_regs, fixed_reg_set);
 
 #ifdef STACK_REGS
   /* Handle STACK_REGS conservatively, since the df-framework does not
      provide accurate information for them.  */
 
   for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
-    SET_HARD_REG_BIT (node->function_used_regs, i);
+    SET_HARD_REG_BIT (function_used_regs, i);
 #endif
 
+  node = cgraph_rtl_info (current_function_decl);
+  gcc_assert (node != NULL);
+
+  COPY_HARD_REG_SET (node->function_used_regs, function_used_regs);
   node->function_used_regs_valid = 1;
 }
 
-- 
1.9.1