https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103585
--- Comment #7 from Jan Hubicka <hubicka at gcc dot gnu.org> --- Created attachment 51952 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51952&action=edit Patch to teach modref about global memory This patch extends modref so we eliminate the dead part of array descriptors. This is done by making difference between accesses to global memory and to unknown memory accesses. The first is less evil since it can not access things that does not escape and it is possible to arrange unanalyzed functions to access only global memory (since everything reaching them escapes). With the patch I now get Performance counter stats for './a.out-badmod': 27,448.82 msec task-clock # 0.999 CPUs utilized 334 context-switches # 12.168 /sec 10 cpu-migrations # 0.364 /sec 70 page-faults # 2.550 /sec 109,079,862,444 cycles # 3.974 GHz 130,234,675 stalled-cycles-frontend # 0.12% frontend cycles idle 80,559,978,185 stalled-cycles-backend # 73.85% backend cycles idle 230,337,342,608 instructions # 2.11 insn per cycle # 0.35 stalled cycles per insn 9,808,852,327 branches # 357.351 M/sec 24,742,926 branch-misses # 0.25% of all branches 27.468971377 seconds time elapsed 27.445934000 seconds user 0.003999000 seconds sys so 56% slowdown is now only 22% which is quite nice improvement. The call of perdida now looks as follows: <bb 70> [local count: 109362591]: _818 = (unsigned long) _44; _817 = _818 + ivtmp.1050_1737; _246 = (real(kind=8) *) _817; parm.326.data = _246; _811 = (unsigned long) _33; _810 = _811 + ivtmp.1050_1737; _247 = (real(kind=8) *) _810; parm.327.data = _247; _712 = (unsigned long) _56; _711 = _712 + ivtmp.1050_1737; _248 = (real(kind=8) *) _711; parm.328.data = _248; _612 = (unsigned long) _20; _574 = _612 + ivtmp.1050_1737; _249 = (real(kind=8) *) _574; parm.329.data = _249; _573 = (unsigned long) _67; _572 = _573 + ivtmp.1050_1737; _250 = (real(kind=8) *) _572; parm.330.data = _250; _251 = (real(kind=8) *) ivtmp.1049_1740; _252 = (real(kind=8) *) ivtmp.1048_1753; _253 = (real(kind=8) *) ivtmp.1047_1762; perdida.constprop (&dt, &lambda, &mu, &yield_stress, &r_infinity, &b, &x_infinity, &gamma, &eta, &plastic_strain_threshold, &parm.326, &parm.327, &parm.328, &parm.329, _253, &parm.330, _252, _251, &failure_threshold, &crack_closure_parameter); parm.326 ={v} {CLOBBER}; parm.327 ={v} {CLOBBER}; parm.328 ={v} {CLOBBER}; parm.329 ={v} {CLOBBER}; parm.330 ={v} {CLOBBER}; and compiles to: movq 48(%rsp), %rax movq %r10, 24(%rsp) addq %rbp, %rax movq %rax, 720(%rsp) movq 32(%rsp), %rax addq %rbp, %rax movq %rax, 816(%rsp) movq 64(%rsp), %rax addq %rbp, %rax movq %rax, 912(%rsp) movq 40(%rsp), %rax addq %rbp, %rax movq %rax, 1008(%rsp) movq 72(%rsp), %rax addq %rbp, %rax addq $72, %rbp movq %rax, 1104(%rsp) leaq 352(%rsp), %rax pushq %rax .cfi_def_cfa_offset 1720 leaq 384(%rsp), %rax pushq %rax .cfi_def_cfa_offset 1728 pushq %r13 .cfi_def_cfa_offset 1736 addq $8, %r13 pushq %r12 .cfi_def_cfa_offset 1744 addq $8, %r12 leaq 1136(%rsp), %rax pushq %rax .cfi_def_cfa_offset 1752 pushq %r14 .cfi_def_cfa_offset 1760 addq $8, %r14 leaq 1056(%rsp), %rax pushq %rax .cfi_def_cfa_offset 1768 leaq 968(%rsp), %rax pushq %rax .cfi_def_cfa_offset 1776 leaq 880(%rsp), %rax pushq %rax .cfi_def_cfa_offset 1784 leaq 792(%rsp), %rax pushq %rax .cfi_def_cfa_offset 1792 leaq 488(%rsp), %rax pushq %rax .cfi_def_cfa_offset 1800 leaq 456(%rsp), %rax pushq %rax .cfi_def_cfa_offset 1808 leaq 480(%rsp), %rax pushq %rax .cfi_def_cfa_offset 1816 leaq 568(%rsp), %rax pushq %rax .cfi_def_cfa_offset 1824 leaq 440(%rsp), %r9 leaq 528(%rsp), %r8 leaq 584(%rsp), %rcx leaq 512(%rsp), %rdx leaq 504(%rsp), %rsi leaq 472(%rsp), %rdi call __perdida_m_MOD_perdida.constprop.0
