myhsu created this revision.
myhsu added reviewers: rsmith, bogner, xur.
Herald added subscribers: cfe-commits, wenlei, dang, dexonsmith, steven_wu,
hiraditya.
Herald added a project: clang.
myhsu requested review of this revision.
Following up https://reviews.llvm.org/D87337 . This patch add the driver
support to propogate `-fprofile-deopt-cold` and
`-fprofile-deopt-cold-percent=<percentage>` flags to codegen and the LTO plugin.
authors: myhsu, probinson, and edd
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D87338
Files:
clang/docs/ClangCommandLineReference.rst
clang/include/clang/Driver/Options.td
clang/lib/Driver/ToolChains/Clang.cpp
clang/lib/Driver/ToolChains/CommonArgs.cpp
clang/test/Driver/deopt-cold-funcs.c
clang/test/Driver/gold-lto-deopt-cold-funcs.c
Index: clang/test/Driver/gold-lto-deopt-cold-funcs.c
===================================================================
--- /dev/null
+++ clang/test/Driver/gold-lto-deopt-cold-funcs.c
@@ -0,0 +1,11 @@
+// RUN: touch %t.o
+//
+// RUN: %clang -### -fprofile-instr-use -fprofile-deopt-cold %t.o -flto 2>&1 \
+// RUN: | FileCheck --check-prefix=CHECK-BASE %s
+
+// RUN: %clang -### -fprofile-instr-use -fprofile-deopt-cold -fprofile-deopt-cold-percent=87 \
+// RUN: %t.o -flto 2>&1 \
+// RUN: | FileCheck --check-prefixes=CHECK-BASE,CHECK-PERCENT %s
+
+// CHECK-BASE: "-plugin-opt=-profile-deopt-cold=true"
+// CHECK-PERCENT: "-plugin-opt=-profile-deopt-cold-percent=87"
Index: clang/test/Driver/deopt-cold-funcs.c
===================================================================
--- /dev/null
+++ clang/test/Driver/deopt-cold-funcs.c
@@ -0,0 +1,15 @@
+// RUN: %clang -### -fprofile-instr-use -fprofile-deopt-cold -c %s 2>&1 \
+// RUN: | FileCheck --check-prefix=CHECK-BASE %s
+
+// RUN: %clang -### -fprofile-instr-use \
+// RUN: -fprofile-deopt-cold -fprofile-deopt-cold-percent=87 \
+// RUN: -c %s 2>&1 \
+// RUN: | FileCheck --check-prefixes=CHECK-BASE,CHECK-PERCENT %s
+
+// Shouldn't do anything if it's not using PGO profile
+// RUN: %clang -### -fprofile-deopt-cold -c %s 2>&1 \
+// RUN: | FileCheck --check-prefix=CHECK-NO-PGO %s
+
+// CHECK-BASE: "-mllvm" "-profile-deopt-cold=true"
+// CHECK-PERCENT: "-mllvm" "-profile-deopt-cold-percent=87"
+// CHECK-NO-PGO-NOT: "-profile-deopt-cold=true"
Index: clang/lib/Driver/ToolChains/CommonArgs.cpp
===================================================================
--- clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -516,6 +516,16 @@
llvm::sys::path::append(Path, "default.profdata");
CmdArgs.push_back(Args.MakeArgString(Twine("-plugin-opt=cs-profile-path=") +
Path));
+ // Propagate -profile-deopt-cold options
+ if (Args.hasFlag(options::OPT_fprofile_deopt_cold,
+ options::OPT_fno_profile_deopt_cold, false)) {
+ CmdArgs.push_back("-plugin-opt=-profile-deopt-cold=true");
+ Arg *A = Args.getLastArg(options::OPT_fprofile_deopt_cold_percent_EQ);
+ if (A) {
+ CmdArgs.push_back(Args.MakeArgString(
+ Twine("-plugin-opt=-profile-deopt-cold-percent=") + A->getValue()));
+ }
+ }
}
// Need this flag to turn on new pass manager via Gold plugin.
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -824,6 +824,19 @@
CmdArgs.push_back(
Args.MakeArgString(Twine("-fprofile-instrument-use-path=") + Path));
}
+ // Tell profile passes to deopt cold functions.
+ if (Args.hasFlag(options::OPT_fprofile_deopt_cold,
+ options::OPT_fno_profile_deopt_cold)) {
+ CmdArgs.push_back("-mllvm");
+ CmdArgs.push_back("-profile-deopt-cold=true");
+
+ if (Arg *A =
+ Args.getLastArg(options::OPT_fprofile_deopt_cold_percent_EQ)) {
+ CmdArgs.push_back("-mllvm");
+ CmdArgs.push_back(Args.MakeArgString(
+ Twine("-profile-deopt-cold-percent=") + A->getValue()));
+ }
+ }
}
bool EmitCovNotes = Args.hasFlag(options::OPT_ftest_coverage,
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -793,6 +793,17 @@
Alias<fdebug_compilation_dir>;
defm debug_info_for_profiling : OptInFFlag<"debug-info-for-profiling",
"Emit extra debug info to make sample profile more accurate">;
+
+// New option to deopt cold code.
+def fprofile_deopt_cold : Flag<["-"], "fprofile-deopt-cold">,
+ Group<f_Group>, Flags<[CoreOption]>,
+ HelpText<"Do not optimize functions that profiling indicates are cold">;
+def fno_profile_deopt_cold : Flag<["-"], "fno-profile-deopt-cold">,
+ Group<f_Group>, Flags<[CoreOption]>;
+def fprofile_deopt_cold_percent_EQ : Joined<["-"], "fprofile-deopt-cold-percent=">,
+ Group<f_Group>, Flags<[CoreOption]>,
+ HelpText<"Do not optimize functions whose profiling count is lower than this percentage">;
+
def fprofile_instr_generate : Flag<["-"], "fprofile-instr-generate">,
Group<f_Group>, Flags<[CoreOption]>,
HelpText<"Generate instrumented code to collect execution counts into default.profraw file (overridden by '=' form of option or LLVM_PROFILE_FILE env var)">;
Index: clang/docs/ClangCommandLineReference.rst
===================================================================
--- clang/docs/ClangCommandLineReference.rst
+++ clang/docs/ClangCommandLineReference.rst
@@ -2016,6 +2016,16 @@
Use instrumentation data for profile-guided optimization. If pathname is a directory, it reads from <pathname>/default.profdata. Otherwise, it reads from file <pathname>.
+.. option:: -fprofile-deopt-cold, -fno-profile-deopt-cold
+
+Adds ``optnone`` attributes to functions whose instrumentation-based PGO profiling counts are equal to zero (i.e. "cold").
+
+.. program:: clang1
+.. option:: -fprofile-deopt-cold-percent=<percentage>
+.. program:: clang
+
+If ``-fprofile-deopt-cold`` is specified, this allows you to choose the lower <percentage>% of functions, sorted by their profiling counts, as the cold functions to be de-optimized.
+
.. option:: -freciprocal-math, -fno-reciprocal-math
Allow division operations to be reassociated
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