[Bug tree-optimization/85509] fails to promote local static to const
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85509 Andrew Pinski changed: What|Removed |Added Severity|normal |enhancement --- Comment #6 from Andrew Pinski --- For some reason CCP1 is not able to do it but CCP2 can; though CCP2 is after inlining so IPA so nothing is done with respect to inlining and such. CCP1 dump: Visiting statement: # VUSE <.MEM_13> PerformSafely.3_3 = _ZZL7RunTestvE13PerformSafelyD.2380; which is likely CONSTANT Lattice value changed to VARYING. Adding SSA edges to worklist. CCP2 dump: Visiting statement: # VUSE <.MEM_8> # PT = nonlocal escaped null PerformSafely.2_2 = _ZZ7RunTestvE13PerformSafelyD.2379; which is likely CONSTANT Lattice value changed to CONSTANT _Z7PerformIL_ZL9SumSafelyRiRKiEEbS0_S2_D.2380. Adding SSA edges to worklist. marking stmt to be not simulated again
[Bug tree-optimization/85509] fails to promote local static to const
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85509 Richard Biener changed: What|Removed |Added Keywords||missed-optimization Status|UNCONFIRMED |NEW Last reconfirmed||2018-04-24 CC||hubicka at gcc dot gnu.org, ||rguenth at gcc dot gnu.org Component|c++ |tree-optimization Summary|auto (function pointer) |fails to promote local |undermining inline |static to const |expansion with GCC but not | |LLVM| Ever confirmed|0 |1 --- Comment #2 from Richard Biener --- The issue is you fail to make PerformQuickly and PerformSafely const and GCC doesn't have local analysis to promote it so and IPA analysis is too late for that since it is also the last inlining point. Slight complication is nested functions and OMP outlining which may refer to these variables. But even the initial cgraph build should be able to figure out the const-ness, no? Workaround: make the vars const.
[Bug tree-optimization/85509] fails to promote local static to const
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85509 --- Comment #3 from ASA --- (In reply to Richard Biener from comment #2) > The issue is you fail to make PerformQuickly and PerformSafely const and GCC > doesn't have local analysis to promote it so and IPA analysis is too late > for that since it is also the last inlining point. > > Slight complication is nested functions and OMP outlining which may refer to > these variables. But even the initial cgraph build should be able to figure > out the const-ness, no? > > Workaround: make the vars const. I stated that const solves the issue in the description. If the auto variables have automatic duration (remove the keyword static), the compiler is able to inline the invocation without the const qualifier. As stated, LLVM (clang++) does inline the invocation even if it has static duration. I would expect this is likely true for any non-const static duration function pointer, not just the case when the auto type specifier is used, but I have not confirmed it.
[Bug tree-optimization/85509] fails to promote local static to const
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85509
--- Comment #4 from Richard Biener ---
(In reply to ASA from comment #3)
> (In reply to Richard Biener from comment #2)
> > The issue is you fail to make PerformQuickly and PerformSafely const and GCC
> > doesn't have local analysis to promote it so and IPA analysis is too late
> > for that since it is also the last inlining point.
> >
> > Slight complication is nested functions and OMP outlining which may refer to
> > these variables. But even the initial cgraph build should be able to figure
> > out the const-ness, no?
> >
> > Workaround: make the vars const.
>
>
> I stated that const solves the issue in the description. If the auto
> variables have automatic duration (remove the keyword static), the compiler
> is able to inline the invocation without the const qualifier. As stated,
> LLVM (clang++) does inline the invocation even if it has static duration.
>
> I would expect this is likely true for any non-const static duration
> function pointer, not just the case when the auto type specifier is used,
> but I have not confirmed it.
But it is the case for any non-const static duration function pointer.
This has nothing to do with 'auto', changing the testcase to
static inline bool
RunTest( void ) {
static bool (*PerformQuickly)(int &, const int &) = Perform< SumQuickly >;
static bool (*PerformSafely)(int &, const int &) = Perform< SumSafely >;
int i = 0;
return PerformQuickly( i, 1 ) && !PerformSafely( i, INT_MAX );
}
has no effect.
[Bug tree-optimization/85509] fails to promote local static to const
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85509
--- Comment #5 from ASA ---
> > I would expect this is likely true for any non-const static duration
> > function pointer, not just the case when the auto type specifier is used,
> > but I have not confirmed it.
>
> But it is the case for any non-const static duration function pointer.
> This has nothing to do with 'auto', changing the testcase to
>
> static inline bool
> RunTest( void ) {
> static bool (*PerformQuickly)(int &, const int &) = Perform< SumQuickly
> >;
> static bool (*PerformSafely)(int &, const int &) = Perform< SumSafely >;
> int i = 0;
> return PerformQuickly( i, 1 ) && !PerformSafely( i, INT_MAX );
> }
>
> has no effect.
Which is exactly what I stated I would have expected. Thank you for the
confirmation of that expectation, though very oddly worded.
