paulkirth updated this revision to Diff 540559.
paulkirth marked an inline comment as done.
paulkirth edited the summary of this revision.
paulkirth added a comment.
Revise tests + update summary
- Add driver tests for -S
- Add codegen tests for -S
- Test Unified LTO codegen
- Use -fdriver-only to test that -ffat-lto-objects isn't unused
- Test that the embedded bitcode has the correct module options set in object
files
- Check that the .llvm.lto section exists when we generate ELF
- Make sure we set any FatLTO related module flags, even for other
BackendActions(e.g., -emit-llvm), so that the IR emitted will match the IR
embedded in the object file
I realized when writing the UnifiedLTO test that the existing implementation
wouldn't actually emit the correct IR using `-emit-llvm` for FatLTO. The flags
were set correctly in the .llvm.lto section, so I slightly adjusted the way we
set flags for the FatLTO case, so that `-ffat-lto-objects -emit-llvm` will have
the same module flags. The issue was that FatLTO isn't mutually exclusive w/
the other BackendActions, so my use of `if else` wasn't correct, and stopped us
from adding any flags when we used `-emit-llvm`. I missed this, since we set the
flags the same way.
The new tests in CodeGen may be a bit overkill, but they were already helpful in
finding this subtle bug.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D146777/new/
https://reviews.llvm.org/D146777
Files:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/CodeGenOptions.def
clang/include/clang/Driver/Options.td
clang/lib/CodeGen/BackendUtil.cpp
clang/lib/Driver/Driver.cpp
clang/lib/Driver/ToolChains/Clang.cpp
clang/lib/Driver/ToolChains/CommonArgs.cpp
clang/test/CodeGen/fat-lto-objects.c
clang/test/Driver/clang_f_opts.c
clang/test/Driver/fat-lto-objects.c
Index: clang/test/Driver/fat-lto-objects.c
===================================================================
--- /dev/null
+++ clang/test/Driver/fat-lto-objects.c
@@ -0,0 +1,34 @@
+// RUN: %clang --target=x86_64-unknown-linux-gnu -flto -ffat-lto-objects -### %s -c 2>&1 | FileCheck %s -check-prefix=CHECK-CC
+// CHECK-CC: -cc1
+// CHECK-CC-SAME: -emit-obj
+// CHECK-CC-SAME: -ffat-lto-objects
+
+/// Without -flto -S will just emit normal ASM, so we don't expect -emit-{llvm,obj} or -ffat-lto-objects to be passed to cc1.
+// RUN: %clang --target=x86_64-unknown-linux-gnu -ffat-lto-objects -### %s -S 2>&1 | FileCheck %s -check-prefix=CHECK-CC-S
+// CHECK-CC-S: -cc1
+// CHECK-CC-S: -S
+// CHECK-CC-S-NOT: -emit-obj
+// CHECK-CC-S-NOT: -emit-llvm
+// CHECK-CC-S-NOT: -ffat-lto-objects
+
+/// When LTO is enabled, we expect LLVM IR output and -ffat-lto-objects to be passed to cc1.
+// RUN: %clang --target=x86_64-unknown-linux-gnu -flto -ffat-lto-objects -### %s -S 2>&1 | FileCheck %s -check-prefix=CHECK-CC-S-LTO
+// RUN: %clang --target=x86_64-unknown-linux-gnu -flto -ffat-lto-objects -### %s -S -emit-llvm 2>&1 | FileCheck %s -check-prefix=CHECK-CC-S-LTO
+// CHECK-CC-S-LTO: -cc1
+// CHECK-CC-S-LTO-SAME: -emit-llvm
+// CHECK-CC-S-LTO-SAME: -ffat-lto-objects
+
+/// Make sure we don't have a warning for -ffat-lto-objects being unused
+// RUN: %clang --target=x86_64-unknown-linux-gnu -ffat-lto-objects -fdriver-only -Werror -v %s -c 2>&1 | FileCheck %s -check-prefix=CHECK-CC-NOLTO
+// CHECK-CC-NOLTO: -cc1
+// CHECK-CC-NOLTO-SAME: -emit-obj
+// CHECK-CC-NOLTO-NOT: -ffat-lto-objects
+
+/// We need to pass an additional flag (--fat-lto-objects) to lld when linking w/ -flto -ffat-lto-objects
+/// But it should not be there when LTO is disabled w/ -fno-lto
+// RUN: %clang --target=x86_64-unknown-linux-gnu --sysroot=%S/Inputs/basic_cross_linux_tree %s \
+// RUN: -fuse-ld=lld -flto -ffat-lto-objects -### 2>&1 | FileCheck --check-prefix=LTO %s
+// RUN: %clang --target=x86_64-unknown-linux-gnu --sysroot=%S/Inputs/basic_cross_linux_tree %s \
+// RUN: -fuse-ld=lld -fno-lto -ffat-lto-objects -### 2>&1 | FileCheck --check-prefix=NOLTO %s
+// LTO: "--fat-lto-objects"
+// NOLTO-NOT: "--fat-lto-objects"
Index: clang/test/Driver/clang_f_opts.c
===================================================================
--- clang/test/Driver/clang_f_opts.c
+++ clang/test/Driver/clang_f_opts.c
@@ -424,7 +424,6 @@
// CHECK-WARNING-DAG: optimization flag '-fwhole-program' is not supported
// CHECK-WARNING-DAG: optimization flag '-fcaller-saves' is not supported
// CHECK-WARNING-DAG: optimization flag '-freorder-blocks' is not supported
-// CHECK-WARNING-DAG: optimization flag '-ffat-lto-objects' is not supported
// CHECK-WARNING-DAG: optimization flag '-fmerge-constants' is not supported
// CHECK-WARNING-DAG: optimization flag '-finline-small-functions' is not supported
// CHECK-WARNING-DAG: optimization flag '-ftree-dce' is not supported
Index: clang/test/CodeGen/fat-lto-objects.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/fat-lto-objects.c
@@ -0,0 +1,57 @@
+// REQUIRES: x86-registered-target
+
+// RUN: %clang -cc1 -triple x86_64-unknown-linux-gnu -flto=full -ffat-lto-objects -fsplit-lto-unit -emit-llvm < %s | FileCheck %s --check-prefixes=FULL,SPLIT
+// RUN: %clang -cc1 -triple x86_64-unknown-linux-gnu -flto=full -ffat-lto-objects -emit-llvm < %s | FileCheck %s --check-prefixes=FULL,SPLIT
+
+// RUN: %clang -cc1 -triple x86_64-unknown-linux-gnu -flto=thin -fsplit-lto-unit -ffat-lto-objects -emit-llvm < %s | FileCheck %s --check-prefixes=THIN,SPLIT
+// RUN: %clang -cc1 -triple x86_64-unknown-linux-gnu -flto=thin -ffat-lto-objects -emit-llvm < %s | FileCheck %s --check-prefixes=THIN,NOSPLIT
+
+// RUN: %clang -cc1 -triple x86_64-unknown-linux-gnu -flto=full -ffat-lto-objects -fsplit-lto-unit -emit-obj < %s -o %t.full.split.o
+// RUN: llvm-readelf -S %t.full.split.o | FileCheck %s --check-prefixes=ELF
+// RUN: llvm-objcopy --dump-section=.llvm.lto=%t.full.split.bc %t.full.split.o
+// RUN: llvm-dis %t.full.split.bc -o - | FileCheck %s --check-prefixes=FULL,SPLIT,NOUNIFIED
+
+// RUN: %clang -cc1 -triple x86_64-unknown-linux-gnu -flto=full -ffat-lto-objects -emit-obj < %s -o %t.full.nosplit.o
+// RUN: llvm-readelf -S %t.full.nosplit.o | FileCheck %s --check-prefixes=ELF
+// RUN: llvm-objcopy --dump-section=.llvm.lto=%t.full.nosplit.bc %t.full.nosplit.o
+// RUN: llvm-dis %t.full.nosplit.bc -o - | FileCheck %s --check-prefixes=FULL,NOSPLIT,NOUNIFIED
+
+// RUN: %clang -cc1 -triple x86_64-unknown-linux-gnu -flto=thin -fsplit-lto-unit -ffat-lto-objects -emit-obj < %s -o %t.thin.split.o
+// RUN: llvm-readelf -S %t.thin.split.o | FileCheck %s --check-prefixes=ELF
+// RUN: llvm-objcopy --dump-section=.llvm.lto=%t.thin.split.bc %t.thin.split.o
+// RUN: llvm-dis %t.thin.split.bc -o - | FileCheck %s --check-prefixes=THIN,SPLIT,NOUNIFIED
+
+// RUN: %clang -cc1 -triple x86_64-unknown-linux-gnu -flto=thin -ffat-lto-objects -emit-obj < %s -o %t.thin.nosplit.o
+// RUN: llvm-readelf -S %t.thin.nosplit.o | FileCheck %s --check-prefixes=ELF
+// RUN: llvm-objcopy --dump-section=.llvm.lto=%t.thin.nosplit.bc %t.thin.nosplit.o
+// RUN: llvm-dis %t.thin.nosplit.bc -o - | FileCheck %s --check-prefixes=THIN,NOSPLIT,NOUNIFIED
+
+// RUN: %clang -cc1 -triple x86_64-unknown-linux-gnu -flto=thin -funified-lto -ffat-lto-objects -emit-obj < %s -o %t.unified.o
+// RUN: llvm-readelf -S %t.unified.o | FileCheck %s --check-prefixes=ELF
+// RUN: llvm-objcopy --dump-section=.llvm.lto=%t.unified.bc %t.unified.o
+// RUN: llvm-dis %t.unified.bc -o - | FileCheck %s --check-prefixes=THIN,NOSPLIT,UNIFIED
+
+// RUN: %clang -cc1 -triple x86_64-unknown-linux-gnu -flto=full -ffat-lto-objects -fsplit-lto-unit -S < %s -o - \
+// RUN: | FileCheck %s --check-prefixes=ASM
+
+/// Check that the ThinLTO metadata is only set false for full LTO.
+// FULL: ![[#]] = !{i32 1, !"ThinLTO", i32 0}
+// THIN-NOT: ![[#]] = !{i32 1, !"ThinLTO", i32 0}
+
+/// Be sure we enable split LTO units correctly under -ffat-lto-objects.
+// SPLIT: ![[#]] = !{i32 1, !"EnableSplitLTOUnit", i32 1}
+// NOSPLIT: ![[#]] = !{i32 1, !"EnableSplitLTOUnit", i32 0}
+
+// UNIFIED: ![[#]] = !{i32 1, !"UnifiedLTO", i32 1}
+// NOUNIFIED-NOT: ![[#]] = !{i32 1, !"UnifiedLTO", i32 1}
+
+// ELF: .llvm.lto
+
+// ASM: .section .llvm.lto,"e",@progbits
+// ASM-NEXT: .Lllvm.embedded.object:
+// ASM-NEXT: .asciz "BC
+// ASM-NEXT: .size .Lllvm.embedded.object
+
+int test(void) {
+ return 0xabcd;
+}
Index: clang/lib/Driver/ToolChains/CommonArgs.cpp
===================================================================
--- clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -617,6 +617,11 @@
PluginName + Suffix,
Plugin);
CmdArgs.push_back(Args.MakeArgString(Twine(PluginPrefix) + Plugin));
+ } else {
+ // Tell LLD to find and use .llvm.lto section in regular relocatable object
+ // files
+ if (Args.hasArg(options::OPT_ffat_lto_objects))
+ CmdArgs.push_back("--fat-lto-objects");
}
const char *PluginOptPrefix = IsOSAIX ? "-bplugin_opt:" : "-plugin-opt=";
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -7354,6 +7354,22 @@
if (SplitLTOUnit)
CmdArgs.push_back("-fsplit-lto-unit");
+ if (Arg *A = Args.getLastArg(options::OPT_ffat_lto_objects,
+ options::OPT_fno_fat_lto_objects)) {
+ if (IsUsingLTO && A->getOption().matches(options::OPT_ffat_lto_objects)) {
+ assert(LTOMode == LTOK_Full || LTOMode == LTOK_Thin);
+ if (!Triple.isOSBinFormatELF()) {
+ D.Diag(diag::err_drv_unsupported_opt_for_target)
+ << A->getAsString(Args) << TC.getTripleString();
+ }
+ CmdArgs.push_back(Args.MakeArgString(
+ Twine("-flto=") + (LTOMode == LTOK_Thin ? "thin" : "full")));
+ CmdArgs.push_back("-flto-unit");
+ CmdArgs.push_back("-ffat-lto-objects");
+ A->render(Args, CmdArgs);
+ }
+ }
+
if (Arg *A = Args.getLastArg(options::OPT_fglobal_isel,
options::OPT_fno_global_isel)) {
CmdArgs.push_back("-mllvm");
Index: clang/lib/Driver/Driver.cpp
===================================================================
--- clang/lib/Driver/Driver.cpp
+++ clang/lib/Driver/Driver.cpp
@@ -4729,8 +4729,13 @@
}
case phases::Backend: {
if (isUsingLTO() && TargetDeviceOffloadKind == Action::OFK_None) {
- types::ID Output =
- Args.hasArg(options::OPT_S) ? types::TY_LTO_IR : types::TY_LTO_BC;
+ types::ID Output;
+ if (Args.hasArg(options::OPT_S))
+ Output = types::TY_LTO_IR;
+ else if (Args.hasArg(options::OPT_ffat_lto_objects))
+ Output = types::TY_PP_Asm;
+ else
+ Output = types::TY_LTO_BC;
return C.MakeAction<BackendJobAction>(Input, Output);
}
if (isUsingLTO(/* IsOffload */ true) &&
Index: clang/lib/CodeGen/BackendUtil.cpp
===================================================================
--- clang/lib/CodeGen/BackendUtil.cpp
+++ clang/lib/CodeGen/BackendUtil.cpp
@@ -55,6 +55,7 @@
#include "llvm/Target/TargetOptions.h"
#include "llvm/TargetParser/SubtargetFeature.h"
#include "llvm/TargetParser/Triple.h"
+#include "llvm/Transforms/IPO/EmbedBitcodePass.h"
#include "llvm/Transforms/IPO/LowerTypeTests.h"
#include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
#include "llvm/Transforms/InstCombine/InstCombine.h"
@@ -1015,7 +1016,12 @@
});
}
- if (IsThinLTO || (IsLTO && CodeGenOpts.UnifiedLTO)) {
+ bool IsThinOrUnifiedLTO = IsThinLTO || (IsLTO && CodeGenOpts.UnifiedLTO);
+ if (CodeGenOpts.FatLTO) {
+ MPM = PB.buildFatLTODefaultPipeline(Level, IsThinOrUnifiedLTO,
+ IsThinOrUnifiedLTO ||
+ shouldEmitRegularLTOSummary());
+ } else if (IsThinOrUnifiedLTO) {
MPM = PB.buildThinLTOPreLinkDefaultPipeline(Level);
} else if (IsLTO) {
MPM = PB.buildLTOPreLinkDefaultPipeline(Level);
@@ -1071,6 +1077,21 @@
EmitLTOSummary));
}
}
+ if (CodeGenOpts.FatLTO) {
+ // Set module flags, like EnableSplitLTOUnit and UnifiedLTO, since FatLTO
+ // uses a different action than Backend_EmitBC or Backend_EmitLL.
+ bool IsThinOrUnifiedLTO =
+ CodeGenOpts.PrepareForThinLTO ||
+ (CodeGenOpts.PrepareForLTO && CodeGenOpts.UnifiedLTO);
+ if (!TheModule->getModuleFlag("ThinLTO"))
+ TheModule->addModuleFlag(Module::Error, "ThinLTO",
+ uint32_t(IsThinOrUnifiedLTO));
+ if (!TheModule->getModuleFlag("EnableSplitLTOUnit"))
+ TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
+ uint32_t(CodeGenOpts.EnableSplitLTOUnit));
+ if (CodeGenOpts.UnifiedLTO && !TheModule->getModuleFlag("UnifiedLTO"))
+ TheModule->addModuleFlag(Module::Error, "UnifiedLTO", uint32_t(1));
+ }
// Now that we have all of the passes ready, run them.
{
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -2366,6 +2366,11 @@
Flags<[CoreOption, CC1Option]>, Group<f_Group>,
HelpText<"Write minimized bitcode to <file> for the ThinLTO thin link only">,
MarshallingInfoString<CodeGenOpts<"ThinLinkBitcodeFile">>;
+defm fat_lto_objects : BoolFOption<"fat-lto-objects",
+ CodeGenOpts<"FatLTO">, DefaultFalse,
+ PosFlag<SetTrue, [CC1Option], "Enable">,
+ NegFlag<SetFalse, [CC1Option], "Disable">,
+ BothFlags<[CC1Option], " fat LTO object support">>;
def fmacro_backtrace_limit_EQ : Joined<["-"], "fmacro-backtrace-limit=">,
Group<f_Group>, Flags<[NoXarchOption, CC1Option, CoreOption]>,
HelpText<"Set the maximum number of entries to print in a macro expansion backtrace (0 = no limit)">,
@@ -5136,7 +5141,6 @@
defm reorder_blocks : BooleanFFlag<"reorder-blocks">, Group<clang_ignored_gcc_optimization_f_Group>;
defm branch_count_reg : BooleanFFlag<"branch-count-reg">, Group<clang_ignored_gcc_optimization_f_Group>;
defm default_inline : BooleanFFlag<"default-inline">, Group<clang_ignored_gcc_optimization_f_Group>;
-defm fat_lto_objects : BooleanFFlag<"fat-lto-objects">, Group<clang_ignored_gcc_optimization_f_Group>;
defm float_store : BooleanFFlag<"float-store">, Group<clang_ignored_gcc_optimization_f_Group>;
defm friend_injection : BooleanFFlag<"friend-injection">, Group<clang_ignored_f_Group>;
defm function_attribute_list : BooleanFFlag<"function-attribute-list">, Group<clang_ignored_f_Group>;
Index: clang/include/clang/Basic/CodeGenOptions.def
===================================================================
--- clang/include/clang/Basic/CodeGenOptions.def
+++ clang/include/clang/Basic/CodeGenOptions.def
@@ -164,6 +164,7 @@
///< compile step.
CODEGENOPT(LTOUnit, 1, 0) ///< Emit IR to support LTO unit features (CFI, whole
///< program vtable opt).
+CODEGENOPT(FatLTO, 1, 0) ///< Set when -ffat-lto-objects is enabled.
CODEGENOPT(EnableSplitLTOUnit, 1, 0) ///< Enable LTO unit splitting to support
/// CFI and traditional whole program
/// devirtualization that require whole
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -267,6 +267,10 @@
directory (``/tmp`` on \*NIX systems, if none of the environment variables
TMPDIR, TMP, and TEMP are specified).
+- ``-ffat-lto-objects`` can now be used to emit object files with both object
+ code and LLVM bitcode. Previously this flag was ignored for GCC compatibility.
+ (`See patch <https://reviews.llvm.org/D146777>`_).
+
Removed Compiler Flags
-------------------------
- The deprecated flag `-fmodules-ts` is removed. Please use ``-std=c++20``
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