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(stupid_mark_refs): If setting reg set only in this insn and not

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referenced, make REG_UNUSED note.

From-SVN: r14416
This commit is contained in:
Richard Kenner 1997-07-13 15:11:06 -04:00
parent a23ea59844
commit 79d06d29ad
1 changed files with 14 additions and 1 deletions
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15
gcc/stupid.c
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@ -1,5 +1,5 @@
/* Dummy data flow analysis for GNU compiler in nonoptimizing mode.
Copyright (C) 1987, 1991, 1994, 1995, 1996, 1997 Free Software Foundation, Inc.
Copyright (C) 1987, 91, 94, 95, 96, 1997 Free Software Foundation, Inc.
This file is part of GNU CC.
@ -514,6 +514,19 @@ stupid_mark_refs (x, insn)
if (last_setjmp_suid < reg_where_dead[regno])
regs_crosses_setjmp[regno] = 1;
/* If this register is only used in this insn and is only
set, mark it unused. We have to do this even when not
optimizing so that MD patterns which count on this
behavior (e.g., it not causing an output reload on
an insn setting CC) will operate correctly. */
if (GET_CODE (SET_DEST (x)) == REG
&&& REGNO_FIRST_UID (regno) == INSN_UID (insn)
&& REGNO_LAST_UID (regno) == INSN_UID (insn)
&& (code == CLOBBER || ! reg_mentioned_p (SET_DEST (x),
SET_SRC (x))))
REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_UNUSED,
SET_DEST (x), REG_NOTES (insn));
}
}