Options for Basic Block Sections, enabled in D68063 and D73674.
This patch adds clang options:
-fbasic-block-sections={all,<filename>,labels,none} and
-funique-basic-block-section-names.
LLVM Support for basic block sections is already enabled.
+ -fbasic-block-sections={all, <file>, labels, none} : Enables/Disables basic
block sections for all or a subset of basic blocks. "labels" only enables
basic block symbols.
+ -funique-basic-block-section-names: Enables unique section names for
basic block sections, disabled by default.
Differential Revision: https://reviews.llvm.org/D68049
diff --git a/clang/docs/ClangCommandLineReference.rst b/clang/docs/ClangCommandLineReference.rst
index a10e747..4fde603 100644
--- a/clang/docs/ClangCommandLineReference.rst
+++ b/clang/docs/ClangCommandLineReference.rst
@@ -1331,6 +1331,10 @@
.. option:: -fautolink, -fno-autolink
+.. option:: -fbasic-block-sections=labels, -fbasic-block-sections=all, -fbasic-block-sections=list=<arg>, -fbasic-block-sections=none
+
+Generate labels for each basic block or place each basic block or a subset of basic blocks in its own section.
+
.. option:: -fblocks, -fno-blocks
Enable the 'blocks' language feature
diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
index ae479e0..d13d418 100644
--- a/clang/docs/UsersManual.rst
+++ b/clang/docs/UsersManual.rst
@@ -1698,6 +1698,44 @@
$ cd $P/bar && clang -c -funique-internal-linkage-names name_conflict.c
$ cd $P && clang foo/name_conflict.o && bar/name_conflict.o
+**-fbasic-block-sections=[labels, all, list=<arg>, none]**
+
+ Controls whether Clang emits a label for each basic block. Further, with
+ values "all" and "list=arg", each basic block or a subset of basic blocks
+ can be placed in its own unique section.
+
+ With the ``list=<arg>`` option, a file containing the subset of basic blocks
+ that need to placed in unique sections can be specified. The format of the
+ file is as follows. For example, ``list=spec.txt`` where ``spec.txt`` is the
+ following:
+
+ ::
+
+ !foo
+ !!2
+ !_Z3barv
+
+ will place the machine basic block with ``id 2`` in function ``foo`` in a
+ unique section. It will also place all basic blocks of functions ``bar``
+ in unique sections.
+
+ Further, section clusters can also be specified using the ``list=<arg>``
+ option. For example, ``list=spec.txt`` where ``spec.txt`` contains:
+
+ ::
+
+ !foo
+ !!1 !!3 !!5
+ !!2 !!4 !!6
+
+ will create two unique sections for function ``foo`` with the first
+ containing the odd numbered basic blocks and the second containing the
+ even numbered basic blocks.
+
+ Basic block sections allow the linker to reorder basic blocks and enables
+ link-time optimizations like whole program inter-procedural basic block
+ reordering.
+
Profile Guided Optimization
---------------------------
diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
index d202823..89a6723 100644
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -45,6 +45,9 @@
///< aliases to base ctors when possible.
CODEGENOPT(DataSections , 1, 0) ///< Set when -fdata-sections is enabled.
CODEGENOPT(UniqueSectionNames, 1, 1) ///< Set for -funique-section-names.
+CODEGENOPT(UniqueBasicBlockSectionNames, 1, 1) ///< Set for -funique-basic-block-section-names,
+ ///< Produce unique section names with
+ ///< basic block sections.
ENUM_CODEGENOPT(FramePointer, FramePointerKind, 2, FramePointerKind::None) /// frame-pointer: all,non-leaf,none
CODEGENOPT(DisableFree , 1, 0) ///< Don't free memory.
diff --git a/clang/include/clang/Basic/CodeGenOptions.h b/clang/include/clang/Basic/CodeGenOptions.h
index 9799e4d..864ccd5 100644
--- a/clang/include/clang/Basic/CodeGenOptions.h
+++ b/clang/include/clang/Basic/CodeGenOptions.h
@@ -110,6 +110,22 @@
Embed_Marker // Embed a marker as a placeholder for bitcode.
};
+ // This field stores one of the allowed values for the option
+ // -fbasic-block-sections=. The allowed values with this option are:
+ // {"labels", "all", "list=<file>", "none"}.
+ //
+ // "labels": Only generate basic block symbols (labels) for all basic
+ // blocks, do not generate unique sections for basic blocks.
+ // Use the machine basic block id in the symbol name to
+ // associate profile info from virtual address to machine
+ // basic block.
+ // "all" : Generate basic block sections for all basic blocks.
+ // "list=<file>": Generate basic block sections for a subset of basic blocks.
+ // The functions and the machine basic block ids are specified
+ // in the file.
+ // "none": Disable sections/labels for basic blocks.
+ std::string BBSections;
+
enum class FramePointerKind {
None, // Omit all frame pointers.
NonLeaf, // Keep non-leaf frame pointers.
diff --git a/clang/include/clang/Basic/DiagnosticFrontendKinds.td b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
index 9df3e79..687c60c 100644
--- a/clang/include/clang/Basic/DiagnosticFrontendKinds.td
+++ b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -110,6 +110,9 @@
"-fconcepts-ts is deprecated - use '-std=c++20' for Concepts support">,
InGroup<Deprecated>;
+def err_fe_unable_to_load_basic_block_sections_file : Error<
+ "unable to load basic block sections function list: '%0'">;
+
def warn_fe_serialized_diag_merge_failure : Warning<
"unable to merge a subprocess's serialized diagnostics">,
InGroup<SerializedDiagnostics>;
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 0bbeeaf..3a5f756 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1988,6 +1988,11 @@
Flags<[CC1Option]>,
HelpText<"Place each function in its own section">;
def fno_function_sections : Flag<["-"], "fno-function-sections">, Group<f_Group>;
+def fbasic_block_sections_EQ : Joined<["-"], "fbasic-block-sections=">, Group<f_Group>,
+ Flags<[CC1Option, CC1AsOption]>,
+ HelpText<"Place each function's basic blocks in unique sections (ELF Only) : all | labels | none | list=<file>">,
+ DocBrief<[{Generate labels for each basic block or place each basic block or a subset of basic blocks in its own section.}]>,
+ Values<"all,labels,none,list=">;
def fdata_sections : Flag <["-"], "fdata-sections">, Group<f_Group>,
Flags<[CC1Option]>, HelpText<"Place each data in its own section">;
def fno_data_sections : Flag <["-"], "fno-data-sections">, Group<f_Group>;
@@ -2002,6 +2007,12 @@
def fno_unique_section_names : Flag <["-"], "fno-unique-section-names">,
Group<f_Group>, Flags<[CC1Option]>;
+def funique_basic_block_section_names : Flag <["-"], "funique-basic-block-section-names">,
+ Group<f_Group>, Flags<[CC1Option]>,
+ HelpText<"Use unique names for basic block sections (ELF Only)">;
+def fno_unique_basic_block_section_names : Flag <["-"], "fno-unique-basic-block-section-names">,
+ Group<f_Group>;
+
def funique_internal_linkage_names : Flag <["-"], "funique-internal-linkage-names">,
Group<f_Group>, Flags<[CC1Option]>,
HelpText<"Uniqueify Internal Linkage Symbol Names by appending the MD5 hash of the module path">;
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index fdf699c..056126d 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -430,7 +430,8 @@
}
}
-static void initTargetOptions(llvm::TargetOptions &Options,
+static void initTargetOptions(DiagnosticsEngine &Diags,
+ llvm::TargetOptions &Options,
const CodeGenOptions &CodeGenOpts,
const clang::TargetOptions &TargetOpts,
const LangOptions &LangOpts,
@@ -488,9 +489,30 @@
Options.NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
Options.UnsafeFPMath = LangOpts.UnsafeFPMath;
Options.StackAlignmentOverride = CodeGenOpts.StackAlignment;
+
+ Options.BBSections =
+ llvm::StringSwitch<llvm::BasicBlockSection>(CodeGenOpts.BBSections)
+ .Case("all", llvm::BasicBlockSection::All)
+ .Case("labels", llvm::BasicBlockSection::Labels)
+ .StartsWith("list=", llvm::BasicBlockSection::List)
+ .Case("none", llvm::BasicBlockSection::None)
+ .Default(llvm::BasicBlockSection::None);
+
+ if (Options.BBSections == llvm::BasicBlockSection::List) {
+ ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
+ MemoryBuffer::getFile(CodeGenOpts.BBSections.substr(5));
+ if (!MBOrErr)
+ Diags.Report(diag::err_fe_unable_to_load_basic_block_sections_file)
+ << MBOrErr.getError().message();
+ else
+ Options.BBSectionsFuncListBuf = std::move(*MBOrErr);
+ }
+
Options.FunctionSections = CodeGenOpts.FunctionSections;
Options.DataSections = CodeGenOpts.DataSections;
Options.UniqueSectionNames = CodeGenOpts.UniqueSectionNames;
+ Options.UniqueBasicBlockSectionNames =
+ CodeGenOpts.UniqueBasicBlockSectionNames;
Options.TLSSize = CodeGenOpts.TLSSize;
Options.EmulatedTLS = CodeGenOpts.EmulatedTLS;
Options.ExplicitEmulatedTLS = CodeGenOpts.ExplicitEmulatedTLS;
@@ -802,7 +824,7 @@
CodeGenOpt::Level OptLevel = getCGOptLevel(CodeGenOpts);
llvm::TargetOptions Options;
- initTargetOptions(Options, CodeGenOpts, TargetOpts, LangOpts, HSOpts);
+ initTargetOptions(Diags, Options, CodeGenOpts, TargetOpts, LangOpts, HSOpts);
TM.reset(TheTarget->createTargetMachine(Triple, TargetOpts.CPU, FeaturesStr,
Options, RM, CM, OptLevel));
}
@@ -1480,15 +1502,12 @@
return nullptr;
}
-static void runThinLTOBackend(ModuleSummaryIndex *CombinedIndex, Module *M,
- const HeaderSearchOptions &HeaderOpts,
- const CodeGenOptions &CGOpts,
- const clang::TargetOptions &TOpts,
- const LangOptions &LOpts,
- std::unique_ptr<raw_pwrite_stream> OS,
- std::string SampleProfile,
- std::string ProfileRemapping,
- BackendAction Action) {
+static void runThinLTOBackend(
+ DiagnosticsEngine &Diags, ModuleSummaryIndex *CombinedIndex, Module *M,
+ const HeaderSearchOptions &HeaderOpts, const CodeGenOptions &CGOpts,
+ const clang::TargetOptions &TOpts, const LangOptions &LOpts,
+ std::unique_ptr<raw_pwrite_stream> OS, std::string SampleProfile,
+ std::string ProfileRemapping, BackendAction Action) {
StringMap<DenseMap<GlobalValue::GUID, GlobalValueSummary *>>
ModuleToDefinedGVSummaries;
CombinedIndex->collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
@@ -1558,7 +1577,7 @@
Conf.RelocModel = CGOpts.RelocationModel;
Conf.CGOptLevel = getCGOptLevel(CGOpts);
Conf.OptLevel = CGOpts.OptimizationLevel;
- initTargetOptions(Conf.Options, CGOpts, TOpts, LOpts, HeaderOpts);
+ initTargetOptions(Diags, Conf.Options, CGOpts, TOpts, LOpts, HeaderOpts);
Conf.SampleProfile = std::move(SampleProfile);
Conf.PTO.LoopUnrolling = CGOpts.UnrollLoops;
// For historical reasons, loop interleaving is set to mirror setting for loop
@@ -1648,8 +1667,8 @@
// of an error).
if (CombinedIndex) {
if (!CombinedIndex->skipModuleByDistributedBackend()) {
- runThinLTOBackend(CombinedIndex.get(), M, HeaderOpts, CGOpts, TOpts,
- LOpts, std::move(OS), CGOpts.SampleProfileFile,
+ runThinLTOBackend(Diags, CombinedIndex.get(), M, HeaderOpts, CGOpts,
+ TOpts, LOpts, std::move(OS), CGOpts.SampleProfileFile,
CGOpts.ProfileRemappingFile, Action);
return;
}
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index dd83caf..4dfc41c 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4205,10 +4205,13 @@
options::OPT_fno_function_sections,
options::OPT_fdata_sections,
options::OPT_fno_data_sections,
+ options::OPT_fbasic_block_sections_EQ,
options::OPT_funique_internal_linkage_names,
options::OPT_fno_unique_internal_linkage_names,
options::OPT_funique_section_names,
options::OPT_fno_unique_section_names,
+ options::OPT_funique_basic_block_section_names,
+ options::OPT_fno_unique_basic_block_section_names,
options::OPT_mrestrict_it,
options::OPT_mno_restrict_it,
options::OPT_mstackrealign,
@@ -4826,6 +4829,16 @@
CmdArgs.push_back("-ffunction-sections");
}
+ if (Arg *A = Args.getLastArg(options::OPT_fbasic_block_sections_EQ)) {
+ StringRef Val = A->getValue();
+ if (Val != "all" && Val != "labels" && Val != "none" &&
+ !(Val.startswith("list=") && llvm::sys::fs::exists(Val.substr(5))))
+ D.Diag(diag::err_drv_invalid_value)
+ << A->getAsString(Args) << A->getValue();
+ else
+ A->render(Args, CmdArgs);
+ }
+
if (Args.hasFlag(options::OPT_fdata_sections, options::OPT_fno_data_sections,
UseSeparateSections)) {
CmdArgs.push_back("-fdata-sections");
@@ -4839,6 +4852,10 @@
options::OPT_fno_unique_internal_linkage_names, false))
CmdArgs.push_back("-funique-internal-linkage-names");
+ if (Args.hasFlag(options::OPT_funique_basic_block_section_names,
+ options::OPT_fno_unique_basic_block_section_names, false))
+ CmdArgs.push_back("-funique-basic-block-section-names");
+
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 ce038d7..6f11eca 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -937,10 +937,19 @@
Opts.TrapFuncName = std::string(Args.getLastArgValue(OPT_ftrap_function_EQ));
Opts.UseInitArray = !Args.hasArg(OPT_fno_use_init_array);
- Opts.FunctionSections = Args.hasArg(OPT_ffunction_sections);
+ Opts.BBSections =
+ std::string(Args.getLastArgValue(OPT_fbasic_block_sections_EQ, "none"));
+
+ // Basic Block Sections implies Function Sections.
+ Opts.FunctionSections =
+ Args.hasArg(OPT_ffunction_sections) ||
+ (Opts.BBSections != "none" && Opts.BBSections != "labels");
+
Opts.DataSections = Args.hasArg(OPT_fdata_sections);
Opts.StackSizeSection = Args.hasArg(OPT_fstack_size_section);
Opts.UniqueSectionNames = !Args.hasArg(OPT_fno_unique_section_names);
+ Opts.UniqueBasicBlockSectionNames =
+ Args.hasArg(OPT_funique_basic_block_section_names);
Opts.UniqueInternalLinkageNames =
Args.hasArg(OPT_funique_internal_linkage_names);
diff --git a/clang/test/CodeGen/Inputs/basic-block-sections.funcnames b/clang/test/CodeGen/Inputs/basic-block-sections.funcnames
new file mode 100644
index 0000000..329cea9
--- /dev/null
+++ b/clang/test/CodeGen/Inputs/basic-block-sections.funcnames
@@ -0,0 +1 @@
+!world
diff --git a/clang/test/CodeGen/basic-block-sections.c b/clang/test/CodeGen/basic-block-sections.c
new file mode 100644
index 0000000..6cdea79
--- /dev/null
+++ b/clang/test/CodeGen/basic-block-sections.c
@@ -0,0 +1,47 @@
+// REQUIRES: x86-registered-target
+
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -S -o - < %s | FileCheck %s --check-prefix=PLAIN
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -S -fbasic-block-sections=all -fbasic-block-sections=none -o - < %s | FileCheck %s --check-prefix=PLAIN
+
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -S -fbasic-block-sections=labels -o - < %s | FileCheck %s --check-prefix=BB_LABELS
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -S -fbasic-block-sections=all -o - < %s | FileCheck %s --check-prefix=BB_WORLD --check-prefix=BB_ALL
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -S -fbasic-block-sections=list=%S/Inputs/basic-block-sections.funcnames -o - < %s | FileCheck %s --check-prefix=BB_WORLD --check-prefix=BB_LIST
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -S -fbasic-block-sections=all -funique-basic-block-section-names -o - < %s | FileCheck %s --check-prefix=UNIQUE
+
+int world(int a) {
+ if (a > 10)
+ return 10;
+ else if (a > 5)
+ return 5;
+ else
+ return 0;
+}
+
+int another(int a) {
+ if (a > 10)
+ return 20;
+ return 0;
+}
+
+// PLAIN-NOT: section
+// PLAIN: world:
+//
+// BB_LABELS-NOT: section
+// BB_LABELS: world:
+// BB_LABELS: a.BB.world:
+// BB_LABELS: aa.BB.world:
+// BB_LABELS: a.BB.another:
+//
+// BB_WORLD: .section .text.world,"ax",@progbits{{$}}
+// BB_WORLD: world:
+// BB_WORLD: .section .text.world,"ax",@progbits,unique
+// BB_WORLD: world.1:
+// BB_WORLD: .section .text.another,"ax",@progbits
+// BB_ALL: .section .text.another,"ax",@progbits,unique
+// BB_ALL: another.1:
+// BB_LIST-NOT: .section .text.another,"ax",@progbits,unique
+// BB_LIST: another:
+// BB_LIST-NOT: another.1:
+//
+// UNIQUE: .section .text.world.world.1,
+// UNIQUE: .section .text.another.another.1,
diff --git a/clang/test/Driver/fbasic-block-sections.c b/clang/test/Driver/fbasic-block-sections.c
new file mode 100644
index 0000000..2ff98c9
--- /dev/null
+++ b/clang/test/Driver/fbasic-block-sections.c
@@ -0,0 +1,9 @@
+// RUN: %clang -### -fbasic-block-sections=none %s -S 2>&1 | FileCheck -check-prefix=CHECK-OPT-NONE %s
+// RUN: %clang -### -fbasic-block-sections=all %s -S 2>&1 | FileCheck -check-prefix=CHECK-OPT-ALL %s
+// RUN: %clang -### -fbasic-block-sections=list=%s %s -S 2>&1 | FileCheck -check-prefix=CHECK-OPT-LIST %s
+// RUN: %clang -### -fbasic-block-sections=labels %s -S 2>&1 | FileCheck -check-prefix=CHECK-OPT-LABELS %s
+//
+// CHECK-OPT-NONE: "-fbasic-block-sections=none"
+// CHECK-OPT-ALL: "-fbasic-block-sections=all"
+// CHECK-OPT-LIST: "-fbasic-block-sections={{[^ ]*}}fbasic-block-sections.c"
+// CHECK-OPT-LABELS: "-fbasic-block-sections=labels"
diff --git a/clang/test/Driver/funique-basic-block-section-names.c b/clang/test/Driver/funique-basic-block-section-names.c
new file mode 100644
index 0000000..56f26b0
--- /dev/null
+++ b/clang/test/Driver/funique-basic-block-section-names.c
@@ -0,0 +1,4 @@
+// RUN: %clang -### -funique-basic-block-section-names %s -S 2>&1 | FileCheck -check-prefix=CHECK-OPT %s
+// RUN: %clang -### -funique-basic-block-section-names -fno-unique-basic-block-section-names %s -S 2>&1 | FileCheck -check-prefix=CHECK-NOOPT %s
+// CHECK-OPT: "-funique-basic-block-section-names"
+// CHECK-NOOPT-NOT: "-funique-basic-block-section-names"