On 10/18/24 7:41 PM, Andrew Pinski wrote:
Sometimes factor_out_conditional_operation can factor out
an operation that causes a phi node to become the same element.
Other times, we want to factor out a binary operator because
it can improve code generation, an example is PR 110015 (openjpeg).
Note this includes a heuristic to decide if factoring out the operation
is profitable or not. It can be expanded to include a better live range
extend detector. Right now it has a simple one where if it is live on a
dominating path, it is considered a live or if there are a small # of
assign statements (defaults to 5), then it does not extend the live range
too much.
Bootstrapped and tested on x86_64-linux-gnu.
PR tree-optimization/112418
gcc/ChangeLog:
* tree-ssa-phiopt.cc (is_factor_profitable): New function.
(factor_out_conditional_operation): Add merge argument. Remove
arg0/arg1 arguments. Return bool instead of the new phi.
Early return for virtual ops. Call is_factor_profitable to
check if the factoring would be profitable.
(pass_phiopt::execute): Call factor_out_conditional_operation
on all phis instead of just singleton phi.
* doc/invoke.texi (--param phiopt-factor-max-stmts-live=): Document.
* params.opt (--param=phiopt-factor-max-stmts-live=): New opt.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/factor_op_phi-1.c: New test.
* gcc.dg/tree-ssa/factor_op_phi-2.c: New test.
* gcc.dg/tree-ssa/factor_op_phi-3.c: New test.
* gcc.dg/tree-ssa/factor_op_phi-4.c: New test.
Dregding up all kinds of old memories.
Not terribly happy with the new param, but a magic constant would
probably be even worse.. So I won't object to that.
OK for the trunk. I wouldn't be terribly surprised if we see light
fallout on some of the crosses, but I don't think that should inherently
block the patch, we'll just fix them up.
Jeff
