https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83349
Bug ID: 83349 Summary: Missed optimization in math expression: aggressive optimization with std::pow Product: gcc Version: 8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: zamazan4ik at tut dot by Target Milestone: --- gcc(trunk) with '--std=c++17 -O3 -march=native -ffast-math' flags for this code: #include <cmath> double test(double a, double x) { return pow(a, x) * a * a * a * a; } generates this assembly: test(double, double): sub rsp, 24 vmovsd QWORD PTR [rsp+8], xmm0 call __pow_finite vmovsd xmm2, QWORD PTR [rsp+8] vmulsd xmm2, xmm2, xmm2 vmulsd xmm2, xmm2, xmm2 vmulsd xmm0, xmm2, xmm0 add rsp, 24 ret As you can see, me can simplify it by adding 4 to 'x' variable and after call std::pow.