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[patch] Avoid ICEing for partial defs in loop-iv.c (PR32405)
- From: Zdenek Dvorak <rakdver at kam dot mff dot cuni dot cz>
- To: gcc-patches at gcc dot gnu dot org
- Cc: zadeck at naturalbridge dot com
- Date: Wed, 20 Jun 2007 08:51:58 +0200
- Subject: [patch] Avoid ICEing for partial defs in loop-iv.c (PR32405)
Hello,
given code like
set (subreg:si REG:di) (something:si)
loop-iv gets confused and believes that DImode register is assigned
SImode value. I am not sure why this did not happen before df branch
merge, probably we produced different ud-chains -- for
set (subreg:si REG:di 0) (something:si)
set (subreg:si REG:di 4) (something:si)
use (REG:di)
we probably had ud-edges to both insns that define REG, while now we
have edge only to the later one; or something like that.
Anyway, the patch below makes us fail for partial defs. Bootstrapped &
regtested on i686, commited.
Zdenek
PR rtl-optimization/32405
* loop-iv.c (iv_get_reaching_def): Fail for partial defs.
Index: loop-iv.c
===================================================================
*** loop-iv.c (revision 125863)
--- loop-iv.c (working copy)
*************** iv_get_reaching_def (rtx insn, rtx reg,
*** 347,352 ****
--- 347,357 ----
return GRD_INVALID;
adef = DF_REF_CHAIN (use)->ref;
+
+ /* We do not handle setting only part of the register. */
+ if (adef->flags & DF_REF_READ_WRITE)
+ return GRD_INVALID;
+
def_insn = DF_REF_INSN (adef);
def_bb = DF_REF_BB (adef);
use_bb = BLOCK_FOR_INSN (insn);