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[PATCH] Fix variable_initial_value
- From: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
- To: gcc-patches at gcc dot gnu dot org
- Date: Wed, 11 Jun 2003 21:00:48 +0200
- Subject: [PATCH] Fix variable_initial_value
Hello,
there is an error in variable_initial_value that causes it to accept
for example x + 42 as a valid initial value for x if x = x + 42 insn
is found; this may cause the number of iterations of the loop to be
determined incorrectly and a miscompilation with -funroll-loops.
I am commiting the obvious patch to fix it.
Zdenek
* cfgloopanal.c (variable_initial_value): Update the set of
altered registers correctly.
Index: cfgloopanal.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cfgloopanal.c,v
retrieving revision 1.1.6.3
diff -c -3 -p -r1.1.6.3 cfgloopanal.c
*** cfgloopanal.c 3 Jun 2003 08:24:01 -0000 1.1.6.3
--- cfgloopanal.c 11 Jun 2003 11:10:33 -0000
*************** variable_initial_value (insn, invariant_
*** 357,368 ****
{
for (; insn != bb->head; insn = PREV_INSN (insn))
{
- if (modified_between_p (var, PREV_INSN (insn), NEXT_INSN (insn)))
- break;
if (INSN_P (insn))
note_stores (PATTERN (insn),
(void (*) PARAMS ((rtx, rtx, void *))) unmark_altered,
invariant_regs);
}
if (insn != bb->head)
--- 357,368 ----
{
for (; insn != bb->head; insn = PREV_INSN (insn))
{
if (INSN_P (insn))
note_stores (PATTERN (insn),
(void (*) PARAMS ((rtx, rtx, void *))) unmark_altered,
invariant_regs);
+ if (modified_between_p (var, PREV_INSN (insn), NEXT_INSN (insn)))
+ break;
}
if (insn != bb->head)