search for: high_mask

...recently. To abstract the relevant parts, it looked something like this: >>> >>> template <typename T> >>> int do_something(T mask, bool cond) { >>> if (mask & 2) >>> return 1; >>> >>> if (cond) { >>> T high_mask = mask >> 48; >>> if (high_mask > 5) >>> do_something_1(high_mask); >>> else if (high_mask > 3) >>> do_something_2(); >>> } >>> >>> return 0; >>> } >>> >>> This function e...

...was >> working on recently. To abstract the relevant parts, it looked >> something like this: >> >> template <typename T> >> int do_something(T mask, bool cond) { >> if (mask & 2) >> return 1; >> >> if (cond) { >> T high_mask = mask >> 48; >> if (high_mask > 5) >> do_something_1(high_mask); >> else if (high_mask > 3) >> do_something_2(); >> } >> >> return 0; >> } >> >> This function ended up being instantiated on different ty...

...ant parts, it looked something like this: >>>> >>>> template <typename T> >>>> int do_something(T mask, bool cond) { >>>> if (mask & 2) >>>> return 1; >>>> >>>> if (cond) { >>>> T high_mask = mask >> 48; >>>> if (high_mask > 5) >>>> do_something_1(high_mask); >>>> else if (high_mask > 3) >>>> do_something_2(); >>>> } >>>> >>>> return 0; >>>> } >>&g...

...ined behavior. Peter Lawrence. For reference here’s your second version with the plain “else” rather than “else if" void do_something_1(int); void do_something_2(); template <typename T> int do_something(T mask, bool cond) { if (mask & 2) return 42; if (cond) { T high_mask = mask >> 48; if (high_mask > 5) do_something_1(high_mask); else do_something_2(); } return 0; } char foo(); bool alwaysfalse(); char f = do_something<char>(foo(), alwaysfalse()); > On Jun 29, 2017, at 2:49 PM, Mehdi AMINI <joker.eph at gmail.com...

...omment on SPEC, but this does remind me of code I was working on recently. To abstract the relevant parts, it looked something like this: > > template <typename T> > int do_something(T mask, bool cond) { > if (mask & 2) > return 1; > > if (cond) { > T high_mask = mask >> 48; > if (high_mask > 5) > do_something_1(high_mask); > else if (high_mask > 3) > do_something_2(); > } > > return 0; > } > > This function ended up being instantiated on different types T (e.g. unsigned char, unsigned in...

...recently. To abstract the relevant parts, it looked something like this: >>> >>> template <typename T> >>> int do_something(T mask, bool cond) { >>> if (mask & 2) >>> return 1; >>> >>> if (cond) { >>> T high_mask = mask >> 48; >>> if (high_mask > 5) >>> do_something_1(high_mask); >>> else if (high_mask > 3) >>> do_something_2(); >>> } >>> >>> return 0; >>> } >>> Hal, yes, there are...

...again incorrect: there is no UB in the program, there is nothing the static analyzer should report. Hal’s example starts with this template > template <typename T> > int do_something(T mask, bool cond) { > if (mask & 2) > return 42; > > if (cond) { > T high_mask = mask >> 48; // UB if sizeof(T) < 8, and cond true > if (high_mask > 5) > do_something_1(high_mask); > else > do_something_2(); > } > > return 0; > } Which is then instantiated with T = char, and where it is impossible f...

...there is nothing the static analyzer should report. > > > Hal’s example starts with this template > >> template <typename T> >> int do_something(T mask, bool cond) { >> if (mask & 2) >> return 42; >> >> if (cond) { >> T high_mask = mask >> 48; // UB if sizeof(T) < 8, and cond true >> if (high_mask > 5) >> do_something_1(high_mask); >> else >> do_something_2(); >> } >> >> return 0; >> } > > > Which is then instantia...

...report. >> >> >> Hal’s example starts with this template >> >>> template <typename T> >>> int do_something(T mask, bool cond) { >>> if (mask & 2) >>> return 42; >>> >>> if (cond) { >>> T high_mask = mask >> 48; // UB if sizeof(T) < 8, and cond true >>> if (high_mask > 5) >>> do_something_1(high_mask); >>> else >>> do_something_2(); >>> } >>> >>> return 0; >>> } >>...

Chandler, where we disagree is in whether the current project is moving the issue forward. It is not. It is making the compiler more complex for no additional value. The current project is not based in evidence, I have asked for any SPEC benchmark that shows performance gain by the compiler taking advantage of “undefined behavior” and no one can show that. The current project

...> Hal’s example starts with this template >>> >>>> template <typename T> >>>> int do_something(T mask, bool cond) { >>>> if (mask & 2) >>>> return 42; >>>> >>>> if (cond) { >>>> T high_mask = mask >> 48; // UB if sizeof(T) < 8, and cond true >>>> if (high_mask > 5) >>>> do_something_1(high_mask); >>>> else >>>> do_something_2(); >>>> } >>>> >>>> retur...

Mehdi, Hal’s transformation only kicks in in the *presence* of UB, and it does not matter how that UB got there, whether by function inlining or without function inlining. The problem with Hal’s argument is that the compiler does not have a built in ouija board with which it can conjure up the spirit of the author of the source code and find out if the UB was intentional with the

...t; Hal’s example starts with this template >>>> >>>> template <typename T> >>>> int do_something(T mask, bool cond) { >>>> if (mask & 2) >>>> return 42; >>>> >>>> if (cond) { >>>> T high_mask = mask >> 48; // UB if sizeof(T) < 8, >>>> and cond true >>>> if (high_mask > 5) >>>> do_something_1(high_mask); >>>> else >>>> do_something_2(); >>>> } >>>> >>...

...his template >>>> >>>>> template <typename T> >>>>> int do_something(T mask, bool cond) { >>>>> if (mask & 2) >>>>> return 42; >>>>> >>>>> if (cond) { >>>>> T high_mask = mask >> 48; // UB if sizeof(T) < 8, and cond true >>>>> if (high_mask > 5) >>>>> do_something_1(high_mask); >>>>> else >>>>> do_something_2(); >>>>> } >>>>>...