[PATCH] Fix PR61657 (undefined behavior in loop-iv.c)
Markus Trippelsdorf
markus@trippelsdorf.de
Fri Aug 21 13:44:00 GMT 2015
bootstrap-ubsan shows:
loop-iv.c:2626:14: runtime error: signed integer overflow: 9223372036854775806 - -9223372036854775808 cannot be represented in type 'long int'
Fixed by moving the variables in question from signed to unsigned.
Bootstrapped and tested on ppc64le.
OK for trunk and gcc-5 branch?
Thanks.
2015-08-21 Markus Trippelsdorf <markus@trippelsdorf.de>
PR rtl-optimization/61657
* loop-iv.c (iv_number_of_iterations): Declare up and down as
unsigned. Remove superflous uint64_t cast.
diff --git a/gcc/loop-iv.c b/gcc/loop-iv.c
index 6e9cc8c..1c9a159 100644
--- a/gcc/loop-iv.c
+++ b/gcc/loop-iv.c
@@ -2330,8 +2330,8 @@ iv_number_of_iterations (struct loop *loop, rtx_insn *insn, rtx condition,
enum rtx_code cond;
machine_mode mode, comp_mode;
rtx mmin, mmax, mode_mmin, mode_mmax;
- uint64_t s, size, d, inv, max;
- int64_t up, down, inc, step_val;
+ uint64_t s, size, d, inv, max, up, down;
+ int64_t inc, step_val;
int was_sharp = false;
rtx old_niter;
bool step_is_pow2;
@@ -2621,7 +2621,7 @@ iv_number_of_iterations (struct loop *loop, rtx_insn *insn, rtx condition,
down = INTVAL (CONST_INT_P (iv0.base)
? iv0.base
: mode_mmin);
- max = (uint64_t) (up - down) / inc + 1;
+ max = (up - down) / inc + 1;
if (!desc->infinite
&& !desc->assumptions)
record_niter_bound (loop, max, false, true);
--
Markus
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