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Patch to fix a bug in LRA inheritance

Message ID 53C01D15.5000908@redhat.com
State New
Headers show

Commit Message

Vladimir Makarov July 11, 2014, 5:21 p.m. UTC 
The following patch fixes a bug in LRA inheritance found on compiling a 
big file on s390x.  Unfortunately, the bug is very hard to reproduce and 
the test is too big and can not be included.  But even if it were 
included, checking a correct code generation would be a problem too.

The bug was in undoing inheritance transformation.  Not all inheritance 
pseudo occurrences were removed which resulted in reading a garbage from 
memory.

The patch was successfully bootstrapped and tested on x86-64.

Committed to the trunk as rev. 212464.

2014-07-11  Vladimir Makarov  <vmakarov@redhat.com>

         * lra-constraints.c (remove_inheritance_pseudos): Process
         destination pseudo too.
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Patch

Index: lra-constraints.c
===================================================================
--- lra-constraints.c	(revision 212460)
+++ lra-constraints.c	(working copy)
@@ -5697,6 +5697,20 @@  remove_inheritance_pseudos (bitmap remov
 			SUBREG_REG (SET_SRC (set)) = SET_SRC (prev_set);
 		      else
 			SET_SRC (set) = SET_SRC (prev_set);
+		      /* As we are finishing with processing the insn
+			 here, check the destination too as it might
+			 inheritance pseudo for another pseudo.  */
+		      if (bitmap_bit_p (remove_pseudos, dregno)
+			  && bitmap_bit_p (&lra_inheritance_pseudos, dregno)
+			  && (restore_regno
+			      = lra_reg_info[dregno].restore_regno) >= 0)
+			{
+			  if (GET_CODE (SET_DEST (set)) == SUBREG)
+			    SUBREG_REG (SET_DEST (set))
+			      = regno_reg_rtx[restore_regno];
+			  else
+			    SET_DEST (set) = regno_reg_rtx[restore_regno];
+			}
 		      lra_push_insn_and_update_insn_regno_info (curr_insn);
 		      lra_set_used_insn_alternative_by_uid
 			(INSN_UID (curr_insn), -1);