[Openmp-dev] Phoronix numbers for clang-omp compiler

[Alexey Bataev]

Jack,
Actually everything is quite simple. Config files for Phoronix test 
suites are using gcc by default and -O2 is provided by default in this 
config files. I think they just compiled these tests by gcc with the 
default config (which already includes -O2) while for clang they had to 
specify some custom options (like "-fopenmp -lgomp", though the second 
one is not needed), but forget to add any optimization options.

Best regards,
Alexey Bataev
=============
Software Engineer
Intel Compiler Team

04.06.2014 22:19, openmp-dev-request at cs.uiuc.edu пишет:
> Message: 4
> Date: Wed, 4 Jun 2014 14:19:49 -0400
> From: Jack Howarth<howarth.mailing.lists at gmail.com>
> To: Andrey Bokhanko<andreybokhanko at gmail.com>
> Cc:"openmp-dev at dcs-maillist2.engr.illinois.edu"
> 	<openmp-dev at dcs-maillist2.engr.illinois.edu>
> Subject: Re: [Openmp-dev] Phoronix numbers for clang-omp compiler
> Message-ID:
> 	<CADtEn-2YdnYNjg3bOcbGxJCJB87fdPyq1oAok4ZFoBTD33Y8Ag at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Andrey,
>       FSF gcc is not exactly defaulting to -O2 but certainly is higher than
> the default optimizations on clang?.
>
> % touch t.cc
> % g++-fsf-4.9 -fverbose-asm t.cc -S
> % more t.s
> # GNU C++ (GCC) version 4.9.0 (x86_64-apple-darwin11.4.2)
> #       compiled by GNU C version 4.9.0, GMP version 6.0.0, MPFR version
> 3.1.2, MPC version 1.0.2
> # GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
> # options passed:  -D__DYNAMIC__ t.cc -fPIC -mmacosx-version-min=10.7.4
> # -mtune=core2 -fverbose-asm
> # options enabled:  -Wnonportable-cfstrings -fPIC
> # -faggressive-loop-optimizations -fasynchronous-unwind-tables
> # -fauto-inc-dec -fcommon -fdelete-null-pointer-checks -fearly-inlining
> # -feliminate-unused-debug-types -fexceptions -ffunction-cse -fgcse-lm
> # -fgnu-unique -fident -finline-atomics -fira-hoist-pressure
> # -fira-share-save-slots -fira-share-spill-slots -fivopts
> # -fkeep-static-consts -fleading-underscore -fmath-errno
> # -fmerge-debug-strings -fnext-runtime -fobjc-abi-version= -fpeephole
> # -fprefetch-loop-arrays -freg-struct-return
> # -fsched-critical-path-heuristic -fsched-dep-count-heuristic
> # -fsched-group-heuristic -fsched-interblock -fsched-last-insn-heuristic
> # -fsched-rank-heuristic -fsched-spec -fsched-spec-insn-heuristic
> # -fsched-stalled-insns-dep -fshow-column -fsigned-zeros
> # -fsplit-ivs-in-unroller -fstrict-volatile-bitfields -fsync-libcalls
> # -ftrapping-math -ftree-coalesce-vars -ftree-cselim -ftree-forwprop
> # -ftree-loop-if-convert -ftree-loop-im -ftree-loop-ivcanon
> # -ftree-loop-optimize -ftree-parallelize-loops= -ftree-phiprop
> # -ftree-reassoc -ftree-scev-cprop -funit-at-a-time -funwind-tables
> # -fverbose-asm -fzero-initialized-in-bss -gstrict-dwarf
> # -m128bit-long-double -m64 -m80387 -malign-stringops -matt-stubs
> # -mconstant-cfstrings -mfancy-math-387 -mfp-ret-in-387 -mfxsr -mieee-fp
> # -mlong-double-80 -mmmx -mno-sse4 -mpush-args -mred-zone -msse -msse2
> # -msse3
>
>          .constructor
>          .destructor
>          .align 1
>          .subsections_via_symbols
>
> % g++-fsf-4.9 -fverbose-asm -O2 t.cc -S
> % more t.s
> # GNU C++ (GCC) version 4.9.0 (x86_64-apple-darwin11.4.2)
> #       compiled by GNU C version 4.9.0, GMP version 6.0.0, MPFR version
> 3.1.2, MPC version 1.0.2
> # GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
> # options passed:  -D__DYNAMIC__ t.cc -fPIC -mmacosx-version-min=10.7.4
> # -mtune=core2 -O2 -fverbose-asm
> # options enabled:  -Wnonportable-cfstrings -fPIC
> # -faggressive-loop-optimizations -fasynchronous-unwind-tables
> # -fauto-inc-dec -fbranch-count-reg -fcaller-saves
> # -fcombine-stack-adjustments -fcommon -fcompare-elim -fcprop-registers
> # -fcrossjumping -fcse-follow-jumps -fdefer-pop
> # -fdelete-null-pointer-checks -fdevirtualize -fdevirtualize-speculatively
> # -fearly-inlining -feliminate-unused-debug-types -fexceptions
> # -fexpensive-optimizations -fforward-propagate -ffunction-cse -fgcse
> # -fgcse-lm -fgnu-unique -fguess-branch-probability -fhoist-adjacent-loads
> # -fident -fif-conversion -fif-conversion2 -findirect-inlining -finline
> # -finline-atomics -finline-functions-called-once -finline-small-functions
> # -fipa-cp -fipa-profile -fipa-pure-const -fipa-reference -fipa-sra
> # -fira-hoist-pressure -fira-share-save-slots -fira-share-spill-slots
> # -fisolate-erroneous-paths-dereference -fivopts -fkeep-static-consts
> # -fleading-underscore -fmath-errno -fmerge-constants -fmerge-debug-strings
> # -fmove-loop-invariants -fnext-runtime -fobjc-abi-version=
> # -fomit-frame-pointer -foptimize-sibling-calls -foptimize-strlen
> # -fpartial-inlining -fpeephole -fpeephole2 -fprefetch-loop-arrays -free
> # -freg-struct-return -freorder-blocks -freorder-blocks-and-partition
> # -freorder-functions -frerun-cse-after-loop
> # -fsched-critical-path-heuristic -fsched-dep-count-heuristic
> # -fsched-group-heuristic -fsched-interblock -fsched-last-insn-heuristic
> # -fsched-rank-heuristic -fsched-spec -fsched-spec-insn-heuristic
> # -fsched-stalled-insns-dep -fschedule-insns2 -fshow-column -fshrink-wrap
> # -fsigned-zeros -fsplit-ivs-in-unroller -fsplit-wide-types
> # -fstrict-aliasing -fstrict-overflow -fstrict-volatile-bitfields
> # -fsync-libcalls -fthread-jumps -ftoplevel-reorder -ftrapping-math
> # -ftree-bit-ccp -ftree-builtin-call-dce -ftree-ccp -ftree-ch
> # -ftree-coalesce-vars -ftree-copy-prop -ftree-copyrename -ftree-cselim
> # -ftree-dce -ftree-dominator-opts -ftree-dse -ftree-forwprop -ftree-fre
> # -ftree-loop-if-convert -ftree-loop-im -ftree-loop-ivcanon
> # -ftree-loop-optimize -ftree-parallelize-loops= -ftree-phiprop -ftree-pre
> # -ftree-pta -ftree-reassoc -ftree-scev-cprop -ftree-sink -ftree-slsr
> # -ftree-sra -ftree-switch-conversion -ftree-tail-merge -ftree-ter
> # -ftree-vrp -funit-at-a-time -funwind-tables -fverbose-asm
> # -fzero-initialized-in-bss -gstrict-dwarf -m128bit-long-double -m64
> # -m80387 -malign-stringops -matt-stubs -mconstant-cfstrings
> # -mfancy-math-387 -mfp-ret-in-387 -mfxsr -mieee-fp -mlong-double-80 -mmmx
> # -mno-sse4 -mpush-args -mred-zone -msse -msse2 -msse3 -mvzeroupper
>
>          .constructor
>          .destructor
>          .align 1
>          .subsections_via_symbols
>
> You might consider filing an enhancement request for clang 3.5 to have the
> default behavior without optimization flags bumped up to -O1.
>           Jack