[llvm-dev] optimization remarks

Wed Aug 15 07:28:36 PDT 2018

Hi Eli,

On 2018-08-14 20:03, Friedman, Eli wrote:
> On 8/14/2018 6:57 AM, Jonas Paulsson via llvm-dev wrote:
>> Hi,
>>
>> I am trying to compare the loop vectorizers effectiveness for 
>> different targets relative to each other. That way, I am hoping to 
>> find loops that are not vectorized - but could be - on my target by 
>> finding other targets doing this successfully. With some luck, there 
>> might be something in the Target files that could be fixed with 
>> improved vectorization as a result...
>>
>> I would like to do this with the optimization remarks enabled: 
>> -Rpass=loop-vectorize, etc. Since cross-compiling benchmarks seems 
>> tricky to me at the moment, my idea was to first run the front end, 
>> and then run the optimizers for different targets. However, when I 
>> pass -save-temps to clang there are no remarks emitted at all any 
>> more... So in effect I can only get the remarks for the target I am 
>> on :-/
>>
>> I wonder if there is a reason for this, or if it's something that 
>> could be fixed?
>>
>
> I think it's just a bug; if you pass -### to clang, you can see how 
> -save-temps actually invokes clang four times, and -Rpass only gets 
> passed to the first invocation.
>

Strange - I see -Rpass in all the invocations... It just doesn't seem to 
have any effect with -save-temps... Am I doing something wrong?

"/home/ijonpan/llvm/build/llvm-dev-2/bin/clang" -c -o toke.o -DSPEC_CPU 
-DNDEBUG -DPERL_CORE   -O3 -march=z14      -DSPEC_CPU -DNDEBUG 
-DPERL_CORE -DSPEC_CPU_LINUX -DSPEC_CPU_BIGENDIAN -D_GNU_SOURCE 
-DSPEC_CPU_LP64 -fno-strict-aliasing -std=gnu90        toke.c 
-Rpass=loop-vectorize -save-temps  -###
clang version 8.0.0 (https://git.llvm.org/git/clang.git/ 
731b1c80ca380ee4d0e68704f8185bb523ce7b23) 
(https://git.llvm.org/git/llvm.git/ 
a3a6a7d1b9744ce5ad40394792adc25e63bc9904)
Target: s390x-ibm-linux
Thread model: posix
InstalledDir: /home/ijonpan/llvm/build/llvm-dev-2/bin
  "/home/ijonpan/llvm/build/llvm-dev-2/bin/clang-8" "-cc1" "-triple" 
"s390x-ibm-linux" "-E" "-save-temps=cwd" "-disable-free" 
"-main-file-name" "toke.c" "-mrelocation-model" "static" 
"-mthread-model" "posix" "-relaxed-aliasing" "-fmath-errno" 
"-masm-verbose" "-mconstructor-aliases" "-fuse-init-array" "-target-cpu" 
"z14" "-dwarf-column-info" "-debugger-tuning=gdb" 
"-momit-leaf-frame-pointer" "-coverage-notes-file" 
"/home/ijonpan/minispec-2006/spec-llvm/400.perlbench/build/toke.gcno" 
"-resource-dir" "/home/ijonpan/llvm/build/llvm-dev-2/lib/clang/8.0.0" 
"-D" "SPEC_CPU" "-D" "NDEBUG" "-D" "PERL_CORE" "-D" "SPEC_CPU" "-D" 
"NDEBUG" "-D" "PERL_CORE" "-D" "SPEC_CPU_LINUX" "-D" 
"SPEC_CPU_BIGENDIAN" "-D" "_GNU_SOURCE" "-D" "SPEC_CPU_LP64" 
"-internal-isystem" "/usr/local/include" "-internal-isystem" 
"/home/ijonpan/llvm/build/llvm-dev-2/lib/clang/8.0.0/include" 
"-internal-externc-isystem" "/include" "-internal-externc-isystem" 
"/usr/include" "-O3" *"-Rpass=loop-vectorize"* "-std=gnu90" 
"-fdebug-compilation-dir" 
"/home/ijonpan/minispec-2006/spec-llvm/400.perlbench/build" 
"-ferror-limit" "19" "-fmessage-length" "225" "-fno-signed-char" 
"-fobjc-runtime=gcc" "-fdiagnostics-show-option" "-fcolor-diagnostics" 
"-vectorize-loops" "-vectorize-slp" "-o" "toke.i" "-x" "c" "toke.c" 
"-faddrsig"
  "/home/ijonpan/llvm/build/llvm-dev-2/bin/clang-8" "-cc1" "-triple" 
"s390x-ibm-linux" "-emit-llvm-bc" "-emit-llvm-uselists" 
"-save-temps=cwd" "-disable-free" "-main-file-name" "toke.c" 
"-mrelocation-model" "static" "-mthread-model" "posix" 
"-relaxed-aliasing" "-fmath-errno" "-masm-verbose" 
"-mconstructor-aliases" "-fuse-init-array" "-target-cpu" "z14" 
"-dwarf-column-info" "-debugger-tuning=gdb" "-momit-leaf-frame-pointer" 
"-coverage-notes-file" 
"/home/ijonpan/minispec-2006/spec-llvm/400.perlbench/build/toke.gcno" 
"-resource-dir" "/home/ijonpan/llvm/build/llvm-dev-2/lib/clang/8.0.0" 
"-O3" *"-Rpass=loop-vectorize"* "-std=gnu90" "-fdebug-compilation-dir" 
"/home/ijonpan/minispec-2006/spec-llvm/400.perlbench/build" 
"-ferror-limit" "19" "-fmessage-length" "225" "-fno-signed-char" 
"-fobjc-runtime=gcc" "-fdiagnostics-show-option" "-fcolor-diagnostics" 
"-vectorize-loops" "-vectorize-slp" "-disable-llvm-passes" "-o" 
"toke.bc" "-x" "cpp-output" "toke.i" "-faddrsig"
  "/home/ijonpan/llvm/build/llvm-dev-2/bin/clang-8" "-cc1" "-triple" 
"s390x-ibm-linux" "-S" "-save-temps=cwd" "-disable-free" 
"-main-file-name" "toke.c" "-mrelocation-model" "static" 
"-mthread-model" "posix" "-relaxed-aliasing" "-fmath-errno" 
"-masm-verbose" "-mconstructor-aliases" "-fuse-init-array" "-target-cpu" 
"z14" "-dwarf-column-info" "-debugger-tuning=gdb" 
"-momit-leaf-frame-pointer" "-coverage-notes-file" 
"/home/ijonpan/minispec-2006/spec-llvm/400.perlbench/build/toke.gcno" 
"-resource-dir" "/home/ijonpan/llvm/build/llvm-dev-2/lib/clang/8.0.0" 
"-O3" *"-Rpass=loop-vectorize"* "-std=gnu90" "-fdebug-compilation-dir" 
"/home/ijonpan/minispec-2006/spec-llvm/400.perlbench/build" 
"-ferror-limit" "19" "-fmessage-length" "225" "-fno-signed-char" 
"-fobjc-runtime=gcc" "-fdiagnostics-show-option" "-fcolor-diagnostics" 
"-vectorize-loops" "-vectorize-slp" "-o" "toke.s" "-x" "ir" "toke.bc" 
"-faddrsig"
  "/home/ijonpan/llvm/build/llvm-dev-2/bin/clang-8" "-cc1as" "-triple" 
"s390x-ibm-linux" "-filetype" "obj" "-main-file-name" "toke.c" 
"-target-cpu" "z14" "-dwarf-version=4" "-mrelocation-model" "static" 
"-o" "toke.o" "toke.s"

"/home/ijonpan/llvm/build/llvm-dev-2/bin/clang" -c -o toke.o -DSPEC_CPU 
-DNDEBUG -DPERL_CORE   -O3 -march=z14 -DSPEC_CPU -DNDEBUG -DPERL_CORE 
-DSPEC_CPU_LINUX -DSPEC_CPU_BIGENDIAN -D_GNU_SOURCE -DSPEC_CPU_LP64 
-fno-strict-aliasing -std=gnu90        toke.c -Rpass=loop-vectorize
toke.c:1483:4: remark: vectorized loop (vectorization width: 4, 
interleaved count: 1) [-Rpass=loop-vectorize]
                         for (c = (U8 *) SvPVX(sv); c < (U8 *)d; c++) {
                         ^
toke.c:1291:7: remark: vectorized loop (vectorization width: 16, 
interleaved count: 1) [-Rpass=loop-vectorize]
                     for (i = min; i <= max; i++)
                     ^
toke.c:1345:3: remark: vectorized loop (vectorization width: 16, 
interleaved count: 1) [-Rpass=loop-vectorize]
                 while (s < regparse)

"/home/ijonpan/llvm/build/llvm-dev-2/bin/clang" -c -o toke.o -DSPEC_CPU 
-DNDEBUG -DPERL_CORE   -O3 -march=z14 -DSPEC_CPU -DNDEBUG -DPERL_CORE 
-DSPEC_CPU_LINUX -DSPEC_CPU_BIGENDIAN -D_GNU_SOURCE -DSPEC_CPU_LP64 
-fno-strict-aliasing -std=gnu90        toke.c -Rpass=loop-vectorize  
-save-temps
(no output)

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