Author: Ellis Hoag Date: 2025-01-10T13:19:33-08:00 New Revision: 91892e8fa3830ed6590eda0bc62e2a2ea8df8872
URL: https://github.com/llvm/llvm-project/commit/91892e8fa3830ed6590eda0bc62e2a2ea8df8872 DIFF: https://github.com/llvm/llvm-project/commit/91892e8fa3830ed6590eda0bc62e2a2ea8df8872.diff LOG: [InstrProf] Add frontend temporal profiling flag (#122385) As discussed in https://github.com/llvm/llvm-project/pull/121514 add the frontend flag `-ftemporal-profile` to enable temporal profiling (https://discourse.llvm.org/t/rfc-temporal-profiling-extension-for-irpgo/68068) as a replacement for `-forder-file-instrumentation` (https://discourse.llvm.org/t/deprecate-forder-file-instrumentation-in-favor-of-temporal-profiling/83903) Added: clang/test/Driver/fprofile-generate-temporal.c Modified: clang/docs/UsersManual.rst clang/include/clang/Driver/Options.td clang/lib/Driver/ToolChains/Clang.cpp clang/test/Driver/clang_f_opts.c Removed: ################################################################################ diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst index 8af9f5be644a02..f58fca465c5494 100644 --- a/clang/docs/UsersManual.rst +++ b/clang/docs/UsersManual.rst @@ -3035,6 +3035,38 @@ indexed format, regardeless whether it is produced by frontend or the IR pass. overhead. ``prefer-atomic`` will be transformed to ``atomic`` when supported by the target, or ``single`` otherwise. +.. option:: -ftemporal-profile + + Enables the temporal profiling extension for IRPGO to improve startup time by + reducing ``.text`` section page faults. To do this, we instrument function + timestamps to measure when each function is called for the first time and use + this data to generate a function order to improve startup. + + The profile is generated as normal. + + .. code-block:: console + + $ clang++ -O2 -fprofile-generate -ftemporal-profile code.cc -o code + $ ./code + $ llvm-profdata merge -o code.profdata yyy/zzz + + Using the resulting profile, we can generate a function order to pass to the + linker via `--symbol-ordering-file` for ELF or `-order_file` for Mach-O. + + .. code-block:: console + + $ llvm-profdata order code.profdata -o code.orderfile + $ clang++ -O2 -Wl,--symbol-ordering-file=code.orderfile code.cc -o code + + Or the profile can be passed to LLD directly. + + .. code-block:: console + + $ clang++ -O2 -fuse-ld=lld -Wl,--irpgo-profile=code.profdata,--bp-startup-sort=function code.cc -o code + + For more information, please read the RFC: + https://discourse.llvm.org/t/rfc-temporal-profiling-extension-for-irpgo/68068 + Fine Tuning Profile Collection ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td index 41a7e8c3728066..80360216c9503a 100644 --- a/clang/include/clang/Driver/Options.td +++ b/clang/include/clang/Driver/Options.td @@ -1796,6 +1796,9 @@ def fprofile_generate_cold_function_coverage : Flag<["-"], "fprofile-generate-co def fprofile_generate_cold_function_coverage_EQ : Joined<["-"], "fprofile-generate-cold-function-coverage=">, Group<f_Group>, Visibility<[ClangOption, CLOption]>, MetaVarName<"<directory>">, HelpText<"Generate instrumented code to collect coverage info for cold functions into <directory>/default.profraw (overridden by LLVM_PROFILE_FILE env var)">; +def ftemporal_profile : Flag<["-"], "ftemporal-profile">, + Group<f_Group>, Visibility<[ClangOption, CLOption]>, + HelpText<"Generate instrumented code to collect temporal information">; def fprofile_instr_generate : Flag<["-"], "fprofile-instr-generate">, Group<f_Group>, Visibility<[ClangOption, CLOption]>, HelpText<"Generate instrumented code to collect execution counts into default.profraw file (overridden by '=' form of option or LLVM_PROFILE_FILE env var)">; @@ -1891,7 +1894,7 @@ defm pseudo_probe_for_profiling : BoolFOption<"pseudo-probe-for-profiling", " pseudo probes for sample profiling">>; def forder_file_instrumentation : Flag<["-"], "forder-file-instrumentation">, Group<f_Group>, Visibility<[ClangOption, CC1Option, CLOption]>, - HelpText<"Generate instrumented code to collect order file into default.profraw file (overridden by '=' form of option or LLVM_PROFILE_FILE env var). Deprecated, please use temporal profiling.">; + HelpText<"Generate instrumented code to collect order file into default.profraw file (overridden by '=' form of option or LLVM_PROFILE_FILE env var). Deprecated, please use -ftemporal-profile">; def fprofile_list_EQ : Joined<["-"], "fprofile-list=">, Group<f_Group>, Visibility<[ClangOption, CC1Option, CLOption]>, HelpText<"Filename defining the list of functions/files to instrument. " diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index f81691f8aeaf95..33f08cf28feca1 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -662,6 +662,14 @@ static void addPGOAndCoverageFlags(const ToolChain &TC, Compilation &C, CmdArgs.push_back("--pgo-function-entry-coverage"); } + if (auto *A = Args.getLastArg(options::OPT_ftemporal_profile)) { + if (!PGOGenerateArg && !CSPGOGenerateArg) + D.Diag(clang::diag::err_drv_argument_only_allowed_with) + << A->getSpelling() << "-fprofile-generate or -fcs-profile-generate"; + CmdArgs.push_back("-mllvm"); + CmdArgs.push_back("--pgo-temporal-instrumentation"); + } + Arg *PGOGenArg = nullptr; if (PGOGenerateArg) { assert(!CSPGOGenerateArg); @@ -8054,7 +8062,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA, Args.getLastArg(options::OPT_forder_file_instrumentation)) { D.Diag(diag::warn_drv_deprecated_arg) << A->getAsString(Args) << /*hasReplacement=*/true - << "-mllvm -pgo-temporal-instrumentation"; + << "-ftemporal-profile"; CmdArgs.push_back("-forder-file-instrumentation"); // Enable order file instrumentation when ThinLTO is not on. When ThinLTO is // on, we need to pass these flags as linker flags and that will be handled diff --git a/clang/test/Driver/clang_f_opts.c b/clang/test/Driver/clang_f_opts.c index 2b72068eae1eeb..38f25898c95568 100644 --- a/clang/test/Driver/clang_f_opts.c +++ b/clang/test/Driver/clang_f_opts.c @@ -424,7 +424,7 @@ // CHECK-WARNING-DAG: optimization flag '-fno-devirtualize-speculatively' is not supported // CHECK-WARNING-DAG: the flag '-fslp-vectorize-aggressive' has been deprecated and will be ignored // CHECK-WARNING-DAG: the flag '-fno-slp-vectorize-aggressive' has been deprecated and will be ignored -// CHECK-WARNING-DAG: argument '-forder-file-instrumentation' is deprecated, use '-mllvm -pgo-temporal-instrumentation' instead +// CHECK-WARNING-DAG: argument '-forder-file-instrumentation' is deprecated, use '-ftemporal-profile' instead // Test that we mute the warning on these // RUN: %clang -### -finline-limit=1000 -Wno-invalid-command-line-argument \ diff --git a/clang/test/Driver/fprofile-generate-temporal.c b/clang/test/Driver/fprofile-generate-temporal.c new file mode 100644 index 00000000000000..8661dc6f8f2626 --- /dev/null +++ b/clang/test/Driver/fprofile-generate-temporal.c @@ -0,0 +1,7 @@ +// RUN: %clang -### -c -fprofile-generate -ftemporal-profile %s 2>&1 | FileCheck %s +// RUN: %clang -### -c -fcs-profile-generate -ftemporal-profile %s 2>&1 | FileCheck %s +// RUN: not %clang -### -c -ftemporal-profile %s 2>&1 | FileCheck %s --check-prefix=ERR + +// CHECK: "-mllvm" "--pgo-temporal-instrumentation" + +// ERR: error: invalid argument '-ftemporal-profile' only allowed with '-fprofile-generate or -fcs-profile-generate' _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
