[clang] f1a3ab9 - [clang] Add a command line flag for the Machine Function Splitter.
Snehasish Kumar via cfe-commits
cfe-commits at lists.llvm.org
Tue Sep 15 12:43:28 PDT 2020
Author: Snehasish Kumar
Date: 2020-09-15T12:41:58-07:00
New Revision: f1a3ab904439a63b21ba1c4521765c46630687c6
URL: https://github.com/llvm/llvm-project/commit/f1a3ab904439a63b21ba1c4521765c46630687c6
DIFF: https://github.com/llvm/llvm-project/commit/f1a3ab904439a63b21ba1c4521765c46630687c6.diff
LOG: [clang] Add a command line flag for the Machine Function Splitter.
This patch adds a command line flag for the machine function splitter
(added in rG94faadaca4e1).
-fsplit-machine-functions
Split machine functions using profile information (x86 ELF). On
other targets an error is emitted. If profile information is not
provided a warning is emitted notifying the user that profile
information is required.
Differential Revision: https://reviews.llvm.org/D87047
Added:
clang/test/Driver/fsplit-machine-functions.c
Modified:
clang/include/clang/Basic/CodeGenOptions.def
clang/include/clang/Driver/Options.td
clang/lib/CodeGen/BackendUtil.cpp
clang/lib/Driver/ToolChains/Clang.cpp
clang/lib/Frontend/CompilerInvocation.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
index feb4ed01f6e8..b5da2a9cde1a 100644
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -162,6 +162,7 @@ CODEGENOPT(NoImplicitFloat , 1, 0) ///< Set when -mno-implicit-float is enable
CODEGENOPT(NullPointerIsValid , 1, 0) ///< Assume Null pointer deference is defined.
CODEGENOPT(CorrectlyRoundedDivSqrt, 1, 0) ///< -cl-fp32-correctly-rounded-divide-sqrt
CODEGENOPT(UniqueInternalLinkageNames, 1, 0) ///< Internal Linkage symbols get unique names.
+CODEGENOPT(SplitMachineFunctions, 1, 0) ///< Split machine functions using profile information.
/// When false, this attempts to generate code as if the result of an
/// overflowing conversion matches the overflowing behavior of a target's native
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index f196c1b72d27..5b39ea513b24 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1996,6 +1996,9 @@ defm unique_internal_linkage_names : OptInFFlag<"unique-internal-linkage-names",
defm unique_section_names : OptOutFFlag<"unique-section-names",
"", "Don't use unique names for text and data sections">;
+defm split_machine_functions: OptInFFlag<"split-machine-functions",
+ "Enable", "Disable", " late function splitting using profile information (x86 ELF)">;
+
defm strict_return : OptOutFFlag<"strict-return", "",
"Don't treat control flow paths that fall off the end of a non-void function as unreachable">;
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 472d86ea2e36..5fc80d4fae71 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -514,6 +514,7 @@ static void initTargetOptions(DiagnosticsEngine &Diags,
Options.BBSectionsFuncListBuf = std::move(*MBOrErr);
}
+ Options.EnableMachineFunctionSplitter = CodeGenOpts.SplitMachineFunctions;
Options.FunctionSections = CodeGenOpts.FunctionSections;
Options.DataSections = CodeGenOpts.DataSections;
Options.UniqueSectionNames = CodeGenOpts.UniqueSectionNames;
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 40659ebb1395..51056960761d 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4911,6 +4911,26 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
options::OPT_fno_unique_basic_block_section_names, false))
CmdArgs.push_back("-funique-basic-block-section-names");
+ if (Arg *A = Args.getLastArg(options::OPT_fsplit_machine_functions,
+ options::OPT_fno_split_machine_functions)) {
+ // This codegen pass is only available on x86-elf targets.
+ if (Triple.isX86() && Triple.isOSBinFormatELF()) {
+ if (A->getOption().matches(options::OPT_fsplit_machine_functions)) {
+ // If the flag is enabled but no profile information is available then
+ // emit a warning.
+ if (getLastProfileUseArg(Args) || getLastProfileSampleUseArg(Args)) {
+ A->render(Args, CmdArgs);
+ } else {
+ D.Diag(diag::warn_drv_diagnostics_hotness_requires_pgo)
+ << A->getAsString(Args);
+ }
+ }
+ } else {
+ D.Diag(diag::err_drv_unsupported_opt_for_target)
+ << A->getAsString(Args) << TripleStr;
+ }
+ }
+
Args.AddLastArg(CmdArgs, options::OPT_finstrument_functions,
options::OPT_finstrument_functions_after_inlining,
options::OPT_finstrument_function_entry_bare);
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 8393ebe9c07a..a88a91182307 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -998,6 +998,8 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
Opts.UniqueInternalLinkageNames =
Args.hasArg(OPT_funique_internal_linkage_names);
+ Opts.SplitMachineFunctions = Args.hasArg(OPT_fsplit_machine_functions);
+
Opts.MergeFunctions = Args.hasArg(OPT_fmerge_functions);
Opts.NoUseJumpTables = Args.hasArg(OPT_fno_jump_tables);
diff --git a/clang/test/Driver/fsplit-machine-functions.c b/clang/test/Driver/fsplit-machine-functions.c
new file mode 100644
index 000000000000..e126e4d41edb
--- /dev/null
+++ b/clang/test/Driver/fsplit-machine-functions.c
@@ -0,0 +1,9 @@
+// RUN: %clang -### -target x86_64 -fprofile-use=default.profdata -fsplit-machine-functions %s -c 2>&1 | FileCheck -check-prefix=CHECK-OPT %s
+// RUN: %clang -### -target x86_64 -fprofile-use=default.profdata -fsplit-machine-functions -fno-split-machine-functions %s -c 2>&1 | FileCheck -check-prefix=CHECK-NOOPT %s
+// RUN: %clang -### -target x86_64 -fsplit-machine-functions %s 2>&1 | FileCheck -check-prefix=CHECK-WARN %s
+// RUN: not %clang -c -target arm-unknown-linux -fsplit-machine-functions %s 2>&1 | FileCheck -check-prefix=CHECK-TRIPLE %s
+
+// CHECK-OPT: "-fsplit-machine-functions"
+// CHECK-NOOPT-NOT: "-fsplit-machine-functions"
+// CHECK-WARN: warning: argument '-fsplit-machine-functions' requires profile-guided optimization information
+// CHECK-TRIPLE: error: unsupported option '-fsplit-machine-functions' for target
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