https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87205
Martin Liška changed:
What|Removed |Added
Status|ASSIGNED|RESOLVED
Resolution|---
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87205
--- Comment #11 from Martin Liška ---
Author: marxin
Date: Wed Sep 5 11:28:49 2018
New Revision: 264124
URL: https://gcc.gnu.org/viewcvs?rev=264124&root=gcc&view=rev
Log:
Group switch cases in switch lowering (PR tree-optimization/87205).
2018
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87205
--- Comment #10 from Martin Liška ---
(In reply to Peter Dimov from comment #8)
> (In reply to Martin Liška from comment #7)
> > I'm not sure here Y are different types here and member access based on
> > the type is distinct.
>
> Yes, one could
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87205
--- Comment #9 from Peter Dimov ---
For more context, see https://godbolt.org/z/SzfpKr
```
#include
template struct variant
{
std::aligned_union_t<0, T...> storage_;
unsigned index_;
};
template
auto visit( variant& v, F f )
{
swi
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87205
--- Comment #8 from Peter Dimov ---
(In reply to Martin Liška from comment #7)
> I'm not sure here Y are different types here and member access based on
> the type is distinct.
Yes, one could argue that, I suppose. But in the `return ((Y<0>*)p)-
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87205
--- Comment #7 from Martin Liška ---
(In reply to Peter Dimov from comment #5)
> Another:
>
> ```
> struct X
> {
> int v;
> };
>
> template struct Y: X
> {
> };
>
> void f( int v );
>
> void h( unsigned ix, void* p )
> {
> switch( ix
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87205
--- Comment #6 from Martin Liška ---
> ```
> h(unsigned int, void*):
> cmp edi, 5
> jbe .L5
> .L5:
> mov rdi, rsi
> jmp f(X*)
> ```
>
> https://godbolt.org/z/2Lh_GZ
Good, my patch can handle that and can generate direct call:
_Z1hjPv:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87205
--- Comment #5 from Peter Dimov ---
Another:
```
struct X
{
int v;
};
template struct Y: X
{
};
void f( int v );
void h( unsigned ix, void* p )
{
switch( ix )
{
case 0: f( ((Y<0>*)p)->v ); break;
case 1: f( ((Y<1>*
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87205
--- Comment #4 from Peter Dimov ---
If the code is not the same the jump table is not optimized out and there's no
extra check. But it also happens with code that is not the same on the C++
side, for example:
```
struct X
{
int v;
};
templa
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87205
Martin Liška changed:
What|Removed |Added
Target Milestone|--- |9.0
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