[Committed][PR64895] Use actual_call_used_reg_set to find conflicting regs

[Committed][PR64895] Use actual_call_used_reg_set to find conflicting regs

[Tom de Vries]

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Hi,

This patch fixes PR64895, related to the gcc.target/i386/fuse-caller-save*.c 
failures for -m32 -fpic.

Bootstrapped and reg-tested on x86_64 for unix/ and unix/-m32.
Build and reg-tested on x86_64 for unix/fpic and unix/fpic/-m32.

Approved here ( https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64895#c7 ):
...
The patch looks ok to me.  Tom, could you prepare the patch (check it mostly for 
x86-64 bootstrap and testsuite) and commit it to the trunk.  I approve it.
...

Thanks,
- Tom

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2015-03-12  Tom de Vries  <tom@codesourcery.com>

	PR rtl-optimization/64895
	* lra-lives.c (check_pseudos_live_through_calls): Use
	actual_call_used_reg_set instead of call_used_reg_set, if available.

diff --git a/gcc/lra-lives.c b/gcc/lra-lives.c
index 9dfffb6..5d759ca 100644
--- a/gcc/lra-lives.c
+++ b/gcc/lra-lives.c
@@ -636,8 +636,12 @@ check_pseudos_live_through_calls (int regno)
   if (! sparseset_bit_p (pseudos_live_through_calls, regno))
     return;
   sparseset_clear_bit (pseudos_live_through_calls, regno);
+  bool actual_call_used_reg_set_available_p
+    = !hard_reg_set_empty_p (lra_reg_info[regno].actual_call_used_reg_set);
   IOR_HARD_REG_SET (lra_reg_info[regno].conflict_hard_regs,
-		    call_used_reg_set);
+		    (actual_call_used_reg_set_available_p
+		     ? lra_reg_info[regno].actual_call_used_reg_set
+		     : call_used_reg_set));
 
   for (hr = 0; hr < FIRST_PSEUDO_REGISTER; hr++)
     if (HARD_REGNO_CALL_PART_CLOBBERED (hr, PSEUDO_REGNO_MODE (regno)))
-- 
1.9.1