[Bug rtl-optimization/14319] incorrect optimization of union of structs with common initial sequences

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=14319 --- Comment #18 from James Kuyper Jr. --- (In reply to Vincent Lefèvre from comment #17) > (In reply to Tim Rentsch from comment #10) > > Four: Despite the last observation, the "one special guarantee" clause > > (and hence also DR 257) is clea

[Bug c/65892] gcc fails to implement N685 aliasing of union members

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65892 --- Comment #59 from James Kuyper Jr. --- (In reply to Davin McCall from comment #56) > (In reply to James Kuyper Jr. from comment #55) > > The problem is, you're using a statement that the access must occur via a > > union, with the implication

[Bug c/65892] gcc fails to implement N685 aliasing of union members

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65892 --- Comment #55 from James Kuyper Jr. --- > ou need, at a minimum, to modify "accesses via" to > "accesses directly via", in order to convey your intended meaning. (In reply to Davin McCall from comment #54) > (In reply to James Kuyper Jr. from

[Bug c/65892] gcc fails to implement N685 aliasing of union members

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65892 --- Comment #53 from James Kuyper Jr. --- (In reply to Davin McCall from comment #52) > (In reply to James Kuyper Jr. from comment #48) > > > The "one special guarantee" clause appears in the section describing union > > > member access via the

[Bug c/65892] gcc fails to implement N685 aliasing of union members

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65892 --- Comment #51 from James Kuyper Jr. --- (In reply to Andrew Haley from comment #49) > (In reply to James Kuyper Jr. from comment #46) > > (In reply to Andrew Haley from comment #42) > > ... > > > In order to use type-based alias analysis in an

[Bug c/65892] gcc fails to implement N685 aliasing of union members

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65892 --- Comment #48 from James Kuyper Jr. --- (In reply to Davin McCall from comment #44) > > Well, perhaps not, but this is the language specification. > > The "one special guarantee" clause appears in the section describing union > member access

[Bug c/65892] gcc fails to implement N685 aliasing of union members

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65892 --- Comment #46 from James Kuyper Jr. --- (In reply to Andrew Haley from comment #42) ... > In order to use type-based alias analysis in any LTO framework it's > necessary to save type information, and this is just more type > information. ...