I noticed while improving forwprop, that fold_stmt sometimes would return true
even if there was no change that happened. These fixes 3 of those places.
In the first one we had:
```
tmp = a ? b : c
if (tmp != 0)
```
And match and simplify would return the same thing but that was just because of
the order of patterns in match.pd.
The second one is that we would return true when simplifying:
```
if (0 != 0)
```
and
```
if (1 != 0)
```
as we would do constant folding on the comparison and then change it back to.
This has an early out so
that we don't even waste time going through constant folding.
The 3rd and final one of this branch is related to the first one where we had:
```
if (bool != 0)
```
and the comparison would simplify back to `bool` which then gets placed back
into the GIMPLE_COND as `bool != 0`.
So we need to reject it while placing it back into the GIMPLE_COND if the
variable didn't change.
There is a 4th patch which I am working on dealing with trapping math and
comparisons. I am trying to figure out the
best way of implementing it.
Thanks,
Andrew Pinski
Andrew Pinski (3):
match: Move `(cmp (cond @0 @1 @2) @3)` simplification after the bool
compare simplifcation
gimple-fold: Return early for GIMPLE_COND with true/false
gimple-fold: Don't replace `bool_var != 0` with `bool_var` inside
GIMPLE_COND
gcc/gimple-fold.cc | 25 ++++++++++++++++++++-----
gcc/match.pd | 31 +++++++++++++++++--------------
2 files changed, 37 insertions(+), 19 deletions(-)
--
2.43.0
