------- Comment #17 from Kyle dot D dot Moffett at boeing dot com 2010-06-04
17:24 -------
Created an attachment (id=20840)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20840&action=view)
Minimal test with -O1
I've managed to shrink this down to a 44-line testcase that fails with the
options listed below. The code is the same but the failure mode is different;
Specifically, I get this output:
|RESET: 252.000000 | 4294967296.000000
|RESET: 504.000000 | 4294967296.000000
|RESET: 756.000000 | 4294967296.000000
|RESET: 1008.000000 | 4294967296.000000
|RESET: 1260.000000 | 4294967296.000000
|RESET: 1512.000000 | 4294967296.000000
|RESET: 1764.000000 | 4294967296.000000
|RESET: 2016.000000 | 4294967296.000000
|RESET: 2268.000000 | 4294967296.000000
=> 2268.000000
|RESET: 2520.000000 | 4294967296.000000
|RESET: 2772.000000 | 4294967296.000000
>From the code, the second floating point value on each line should be equal to
the first float from the previous line. If I change the first "(unsigned long
long)" cast to a "(long long)" cast, the bug goes away and I see the following
(correct) output:
|RESET: 252.000000 | 0.000000
|RESET: 504.000000 | 252.000000
|RESET: 756.000000 | 504.000000
|RESET: 1008.000000 | 756.000000
|RESET: 1260.000000 | 1008.000000
|RESET: 1512.000000 | 1260.000000
|RESET: 1764.000000 | 1512.000000
|RESET: 2016.000000 | 1764.000000
|RESET: 2268.000000 | 2016.000000
=> 2268.000000
|RESET: 2520.000000 | 2268.000000
|RESET: 2772.000000 | 2520.000000
The full list of compile options:
-pipe \
-g \
-Wall \
-fmove-loop-invariants \
-fcaller-saves \
--param max-aliased-vops=100 \
--param avg-aliased-vops=1 \
--param max-fields-for-field-sensitive=0 \
--param loop-invariant-max-bbs-in-loop=1000 \
-O \
-fno-web \
-fno-rename-registers \
-fno-unroll-loops \
-fno-peel-loops \
-fno-split-ivs-in-unroller \
-fno-peephole \
-fno-dce \
-fno-dse \
-fno-unit-at-a-time \
-fno-omit-frame-pointer \
-fno-auto-inc-dec \
-fno-cprop-registers \
-fno-dce \
-fno-defer-pop \
-fno-delayed-branch \
-fno-dse \
-fno-guess-branch-probability \
-fno-if-conversion2 \
-fno-if-conversion \
-fno-inline-small-functions \
-fno-inline-functions-called-once \
-fno-early-inlining \
-fno-ipa-pure-const \
-fno-ipa-reference \
-fno-merge-constants \
-fno-split-wide-types \
-fno-tree-builtin-call-dce \
-fno-tree-ccp \
-fno-tree-ch \
-fno-tree-copyrename \
-fno-tree-dce \
-fno-tree-dominator-opts \
-fno-tree-dse \
-fno-tree-fre \
-fno-tree-sra \
-fno-tree-ter \
-fno-merge-constants \
-fno-branch-count-reg \
-fno-function-cse \
-fno-thread-jumps \
-fno-gcse \
-fno-rerun-cse-after-loop \
-fno-cse-skip-blocks \
-fno-cse-follow-jumps
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44364
