https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70840
Bug ID: 70840
Summary: revisit reassoc handling of pow / powi, amend match.pd
for powi
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
Target Milestone: ---
Currently reassoc builds powi from repeated multiplications guarded with
-funsafe-math-optimizations where later expansion of powi is safe for
fp-contract != off.
The acceptable_pow_call cases are globally guarded with
flag_unsafe_math_optimizations as well but POWI is always safe
and only POW has to be guarded with flag_unsafe_math_optimizations.
match.pd has quite some patterns involving POW but none involving POWI.
At least for flag_unsafe_math_optimizations POWI can be treated as POW
and whether we emit POW or POWI does not matter for
flag_unsafe_math_optimziations.
