Re: RFA: PR 34415: dbr_schedule vs. uninitialised registers

[Richard Sandiford <rsandifo at nildram dot co dot uk>]

Eric Botcazou <ebotcazou@libertysurf.fr> writes:
>> Well, that would work too, but would make the register unnecessarily
>> live in cases where my patch wouldn't (i.e. between the barrier and
>> the place where the register really does become live).  I'm happy
>> to do it that way instead if you prefer though.
>
> My understanding is that resource.c was written with the flow.c way of
> doing things in mind (in particular backward propagation) so, barring
> the scrapping of resource.c itself, I think we'd better keep using a
> backward problem, i.e.  LR instead of LIVE, for resource.c.

OK, here's the patch.  Regression-tested on mipsisa64-elfoabi,
OK to install?

Richard


gcc/
	PR rtl-optimization/34415
	* df.h (DF_LR_IN, DF_LR_OUT): Update comments.
	* resource.c (mark_target_live_regs): Use DF_LR_IN rather than
	df_get_live_in.  Don't handle pseudos.

gcc/testsuite/
	PR rtl-optimization/34415
	* gcc.c-torture/execute/pr34415.c: New test.

Index: gcc/df.h
===================================================================
--- gcc/df.h	2007-12-15 10:23:43.000000000 +0000
+++ gcc/df.h	2007-12-15 10:23:46.000000000 +0000
@@ -559,9 +559,9 @@ #define DF_LIVE_BB_INFO(BB) (df_live_get
 #define DF_LIVE_IN(BB) (DF_LIVE_BB_INFO(BB)->in) 
 #define DF_LIVE_OUT(BB) (DF_LIVE_BB_INFO(BB)->out) 
 
-/* These macros are currently used by only reg-stack since it is not
-   tolerant of uninitialized variables.  This intolerance should be
-   fixed because it causes other problems.  */ 
+/* These macros are used by passes that are not tolerant of
+   uninitialized variables.  This intolerance should eventually
+   be fixed.  */
 #define DF_LR_IN(BB) (DF_LR_BB_INFO(BB)->in) 
 #define DF_LR_OUT(BB) (DF_LR_BB_INFO(BB)->out) 
 
Index: gcc/resource.c
===================================================================
--- gcc/resource.c	2007-12-15 10:23:43.000000000 +0000
+++ gcc/resource.c	2007-12-15 10:57:26.000000000 +0000
@@ -958,9 +958,8 @@ mark_target_live_regs (rtx insns, rtx ta
      TARGET.  Otherwise, we must assume everything is live.  */
   if (b != -1)
     {
-      regset regs_live = df_get_live_in (BASIC_BLOCK (b));
+      regset regs_live = DF_LR_IN (BASIC_BLOCK (b));
       rtx start_insn, stop_insn;
-      reg_set_iterator rsi;
 
       /* Compute hard regs live at start of block -- this is the real hard regs
 	 marked live, plus live pseudo regs that have been renumbered to
@@ -968,13 +967,6 @@ mark_target_live_regs (rtx insns, rtx ta
 
       REG_SET_TO_HARD_REG_SET (current_live_regs, regs_live);
 
-      EXECUTE_IF_SET_IN_REG_SET (regs_live, FIRST_PSEUDO_REGISTER, i, rsi)
-	{
-	  if (reg_renumber[i] >= 0)
-	    add_to_hard_reg_set (&current_live_regs, PSEUDO_REGNO_MODE (i),
-				reg_renumber[i]);
-	}
-
       /* Get starting and ending insn, handling the case where each might
 	 be a SEQUENCE.  */
       start_insn = (b == ENTRY_BLOCK_PTR->next_bb->index ? 
Index: gcc/testsuite/gcc.c-torture/execute/pr34415.c
===================================================================
--- /dev/null	2007-12-15 09:13:22.548096750 +0000
+++ gcc/testsuite/gcc.c-torture/execute/pr34415.c	2007-12-15 10:23:46.000000000 +0000
@@ -0,0 +1,34 @@
+const char *__attribute__((noinline))
+foo (const char *p)
+{
+  const char *end;
+  int len = 1;
+  for (;;)
+    {
+      int c = *p;
+      c = (c >= 'a' && c <= 'z' ? c - 'a' + 'A' : c);
+      if (c == 'B')
+	end = p;
+      else if (c == 'A')
+	{
+	  end = p;
+	  do
+	    p++;
+	  while (*p == '+');
+	}
+      else
+	break;
+      p++;
+      len++;
+    }
+  if (len > 2 && *p == ':')
+    p = end;
+  return p;
+}
+
+int
+main (void)
+{
+  const char *input = "Bbb:";
+  return foo (input) != input + 2;
+}