search for: do_something_2

...ith undefined behavior. So I am puzzled, That’s why I’m still asking for a more concrete example showing how We can optimize based on undefined 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()...

...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 int, unsigned long, etc.) and, dynamically, cond was always false when T was char...

...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 int, unsigned long, etc.) and, dynamically, >> cond was always false when T was char. The question is: Can the &g...

...{ >>> 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 int, unsigned long, etc.) and, dynamically, cond was always false when T was char. The question is: Can t...

...{ >>> 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 times when it is expedient to suppress or ignore warnings, but I don’t believe this is one of them, a suggestion could have been made to change the source code along the lines of...

...t; 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 int, unsigned long, etc.) and, dynamically, cond was always false when T was char. The question is: Can the compiler eliminate all of the code predicated...

...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 for either a static analyzer or a compiler to figure out and prove that ‘cond’ is always false. Hence a static analyzer issues a warning about the shift, while llvm gives no warning an...

...{ >> 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 for either a static analyzer or a > compiler to figure out and prove that ‘cond’ is always false. > > Hence a static analyzer issues a warn...

...>>> 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 for either a static analyzer or a >> compiler to figure out and prove that ‘cond’ is always false. >> &g...

...>>>> >>>> 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 for either a static analyzer or a >>> compiler to figure out and prove that...

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

...>>>> 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 for either a static analyzer or a >>>> compiler to figure out...

...t;>>> 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 for either a static analyzer or a >>>> co...

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

I''m trying desperately to get visuall effects callbacks working in rjs templates to no avail What I''m trying to do is fade an image, change the div with the image to a new image, and then fade the new image back in. How would I go about this in RJS Here''s a simple line from my rjs that I can''t get to work. It is not using callbacks so the