On 9/12/26 1:24 AM, Andrea Pinski wrote:
This adds a simplification for `x+umax(x,1)` to `umax(x*2, 1)` when `x*2`
is known not to overflow. This shows up with std::vector::push_back
after the patch which adds `x+minmax(a,b)` simplification; it is also
a special case of that patch for `umax and 1`. This gives a small
code generation improvement with std::vector::push_back because we
trade an add after the umax with a shift beforehand.
Bootstrapped and tested on x86_64-linux-gnu.
PR tree-optimization/127103
gcc/ChangeLog:
* match.pd (`x+umax(x,1)`): New pattern.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/max1-plus-1.c: New test.
Signed-off-by: Andrea Pinski <[email protected]>
Not objecting, more a general question. It seems like this is just
trading one form for another. We haven't dropped the number of
expression evaluations nor have we reduced the height of the dependency
tree. So this feels more likely a canonicalizatino pattern or a pattern
designed to change forms to make other optimizations more effective. Is
that a fair characterization?
Jeff
