-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 03/24/11 17:57, Andrew MacLeod wrote: > My fault for not being specific about it... I tend to just use data race > as a catch all for all these types of things when talking about them > with Aldy. > > the testcase should have for (x=0; x< limit; x++) sum[x] = global; > rather than x<5, so that its not a known loop count. > > The hoisted load is then not allowed as it become a speculative load of > 'global' on the main path which would not otherwise have been there. > When the value of limit < 0, this can cause a load race detection on > systems with either a software or hardware data race detector. We generally don't allow this kind of code motion anyway -- though it's more because we haven't built any kind of analysis to determine that this kind of speculative load is often profitable and can't result in a fault.
However, having a switch we can throw to avoid this behaviour (assuming we add this kind of speculative code motion one day) is, IMHO, a good thing. Jeff -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJNlHzgAAoJEBRtltQi2kC7h24H/1TJ9gdSKfPwjtiKQL7BLraO yAwvJJJihacO3xM2pkVZIXRVlHwFyqzU03x0ygExMOex3QMuLMByBbpxsk3uQV7t 30xF5MDEdXEmQ7L1jWI7gYXbKZk5lnJhDQKewPePdUbcVzJj3H71SQGP2uWCLMUE 7ToPioN2w3DazoWdnYC/Jqi5JwBLnKpcxkGXQPYbCvqII8W5Xkmlh743Zq5RF7ax q1nAkRmKdsgIq0SJJNF0GVxdzfOQkt1q7yzR7W74PCG1h6Yam6DNsePSbswDSu46 0gxkqnlGb6dkgx1iCHAS0PtNDAurGVCAOd5rijH1yib7C+P48XLmoF10Y13v82I= =D+1J -----END PGP SIGNATURE-----
