tejohnson created this revision.
tejohnson added a reviewer: mehdi_amini.
tejohnson added a subscriber: cfe-commits.
Herald added a subscriber: mehdi_amini.
Currently, a linker option must be used to control the backend
parallelism of ThinLTO or full LTO (where it only applies to
parallel code gen). The linker option varies depending on the
linker (e.g. gold vs ld64). Add a new clang option -flto-jobs=N
to control this.
I've added in the wiring to pass this to the gold plugin. I also
added in the logic to pass this down in the form I understand that
ld64 uses on MacOS, for the darwin target.
https://reviews.llvm.org/D24826
Files:
include/clang/Driver/Options.td
lib/Driver/Tools.cpp
test/Driver/lto-jobs.c
Index: test/Driver/lto-jobs.c
===================================================================
--- /dev/null
+++ test/Driver/lto-jobs.c
@@ -0,0 +1,11 @@
+// Confirm that -flto-jobs=N is passed to linker
+
+// RUN: %clang -target x86_64-unknown-linux -### %s -flto=thin -flto-jobs=5 2> %t
+// RUN: FileCheck -check-prefix=CHECK-LINK-THIN-JOBS-ACTION < %t %s
+//
+// CHECK-LINK-THIN-JOBS-ACTION: "-plugin-opt=jobs=5"
+
+// RUN: %clang -target x86_64-apple-darwin13.3.0 -### %s -flto=thin -flto-jobs=5 2> %t
+// RUN: FileCheck -check-prefix=CHECK-LINK-THIN-JOBS2-ACTION < %t %s
+//
+// CHECK-LINK-THIN-JOBS2-ACTION: "-mllvm" "-threads=5"
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -1998,8 +1998,19 @@
}
}
+static unsigned getLTOParallelism(const ArgList &Args, const Driver &D) {
+ unsigned Parallelism = 0;
+ Arg *LtoJobsArg = Args.getLastArg(options::OPT_flto_jobs_EQ);
+ if (LtoJobsArg &&
+ StringRef(LtoJobsArg->getValue()).getAsInteger(10, Parallelism))
+ D.Diag(diag::err_drv_invalid_int_value) << LtoJobsArg->getAsString(Args)
+ << LtoJobsArg->getValue();
+ return Parallelism;
+}
+
static void AddGoldPlugin(const ToolChain &ToolChain, const ArgList &Args,
- ArgStringList &CmdArgs, bool IsThinLTO) {
+ ArgStringList &CmdArgs, bool IsThinLTO,
+ const Driver &D) {
// Tell the linker to load the plugin. This has to come before AddLinkerInputs
// as gold requires -plugin to come before any -plugin-opt that -Wl might
// forward.
@@ -2032,6 +2043,10 @@
if (IsThinLTO)
CmdArgs.push_back("-plugin-opt=thinlto");
+ if (unsigned Parallelism = getLTOParallelism(Args, D))
+ CmdArgs.push_back(Args.MakeArgString(Twine("-plugin-opt=jobs=") +
+ std::to_string(Parallelism)));
+
// If an explicit debugger tuning argument appeared, pass it along.
if (Arg *A = Args.getLastArg(options::OPT_gTune_Group,
options::OPT_ggdbN_Group)) {
@@ -7639,7 +7654,7 @@
options::OPT_t, options::OPT_Z_Flag, options::OPT_r});
if (D.isUsingLTO())
- AddGoldPlugin(ToolChain, Args, CmdArgs, D.getLTOMode() == LTOK_Thin);
+ AddGoldPlugin(ToolChain, Args, CmdArgs, D.getLTOMode() == LTOK_Thin, D);
AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs);
@@ -8060,6 +8075,13 @@
getMachOToolChain().addProfileRTLibs(Args, CmdArgs);
+ if (unsigned Parallelism =
+ getLTOParallelism(Args, getToolChain().getDriver())) {
+ CmdArgs.push_back("-mllvm");
+ CmdArgs.push_back(
+ Args.MakeArgString(Twine("-threads=") + std::to_string(Parallelism)));
+ }
+
if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
if (getToolChain().getDriver().CCCIsCXX())
getToolChain().AddCXXStdlibLibArgs(Args, CmdArgs);
@@ -8790,7 +8812,7 @@
Args.AddAllArgs(CmdArgs, options::OPT_r);
if (D.isUsingLTO())
- AddGoldPlugin(ToolChain, Args, CmdArgs, D.getLTOMode() == LTOK_Thin);
+ AddGoldPlugin(ToolChain, Args, CmdArgs, D.getLTOMode() == LTOK_Thin, D);
bool NeedsSanitizerDeps = addSanitizerRuntimes(ToolChain, Args, CmdArgs);
AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs);
@@ -9623,7 +9645,7 @@
ToolChain.AddFilePathLibArgs(Args, CmdArgs);
if (D.isUsingLTO())
- AddGoldPlugin(ToolChain, Args, CmdArgs, D.getLTOMode() == LTOK_Thin);
+ AddGoldPlugin(ToolChain, Args, CmdArgs, D.getLTOMode() == LTOK_Thin, D);
if (Args.hasArg(options::OPT_Z_Xlinker__no_demangle))
CmdArgs.push_back("--no-demangle");
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -812,6 +812,11 @@
HelpText<"Enable LTO in 'full' mode">;
def fno_lto : Flag<["-"], "fno-lto">, Group<f_Group>,
HelpText<"Disable LTO mode (default)">;
+def flto_jobs_EQ : Joined<["-"], "flto-jobs=">,
+ Flags<[CC1Option]>, Group<f_Group>,
+ HelpText<"Controls the backend parallelism of -flto=thin (default "
+ "std::thread::hardware_concurrency) or the code generation "
+ "parallelism of -flto=full (default 1)">;
def fthinlto_index_EQ : Joined<["-"], "fthinlto-index=">,
Flags<[CC1Option]>, Group<f_Group>,
HelpText<"Perform ThinLTO importing using provided function summary index">;
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