mtrofin created this revision.
mtrofin added reviewers: tejohnson, zapster.
Herald added subscribers: llvm-commits, cfe-commits, dexonsmith, steven_wu,
hiraditya, inglorion.
Herald added a reviewer: alexshap.
Herald added projects: clang, LLVM.
mtrofin requested review of this revision.
This will embed bitcode after ThinLTO merge, but before optimizations.
In the case the thinlto backend is called from clang, the .llvmcmd
section is also produced. Doing so in the case where the caller is the
linker doesn't yet have a motivation, and would require plumbing through
command line args.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D87636
Files:
clang/lib/CodeGen/BackendUtil.cpp
clang/test/CodeGen/Inputs/start-lib1.ll
clang/test/CodeGen/Inputs/start-lib2.ll
clang/test/CodeGen/thinlto_embed_bitcode.ll
llvm/include/llvm/LTO/LTOBackend.h
llvm/lib/LTO/LTOBackend.cpp
llvm/test/LTO/X86/Inputs/start-lib1.ll
llvm/test/LTO/X86/embed-bitcode.ll
Index: llvm/test/LTO/X86/embed-bitcode.ll
===================================================================
--- llvm/test/LTO/X86/embed-bitcode.ll
+++ llvm/test/LTO/X86/embed-bitcode.ll
@@ -11,13 +11,14 @@
; RUN: llvm-lto2 run -r %t1.o,_start,px -r %t2.o,foo,px -r %t3.o,bar,px -r %t2.o,bar,lx -lto-embed-bitcode=optimized -o %t3 %t1.o %t2.o %t3.o
; RUN: llvm-readelf -S %t3.0 | FileCheck %s --check-prefix=CHECK-ELF
; RUN: llvm-objcopy --dump-section=.llvmbc=%t-embedded.bc %t3.0 /dev/null
-; RUN: llvm-dis %t-embedded.bc -o - | FileCheck %s --check-prefix=CHECK-LL
+; RUN: llvm-dis %t-embedded.bc -o - | FileCheck %s --check-prefixes=CHECK-LL,CHECK-OPT
; CHECK-ELF: .text PROGBITS 0000000000000000 [[#%x,OFF:]] [[#%x,SIZE:]] 00 AX 0
; CHECK-ELF-NEXT: .llvmbc PROGBITS 0000000000000000 [[#%x,OFF:]] [[#%x,SIZE:]] 00 0
; CHECK-LL: @_start
; CHECK-LL: @foo
+; CHECK-OPT-NEXT: ret void
; CHECK-LL: @bar
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
Index: llvm/lib/LTO/LTOBackend.cpp
===================================================================
--- llvm/lib/LTO/LTOBackend.cpp
+++ llvm/lib/LTO/LTOBackend.cpp
@@ -50,17 +50,23 @@
using namespace llvm;
using namespace lto;
+#define DEBUG_TYPE "lto-backend"
+
enum class LTOBitcodeEmbedding {
DoNotEmbed = 0,
EmbedOptimized = 1,
+ EmbedPostThinLTOMerge = 2
};
static cl::opt<LTOBitcodeEmbedding> EmbedBitcode(
"lto-embed-bitcode", cl::init(LTOBitcodeEmbedding::DoNotEmbed),
- cl::values(clEnumValN(LTOBitcodeEmbedding::DoNotEmbed, "none",
- "Do not embed"),
- clEnumValN(LTOBitcodeEmbedding::EmbedOptimized, "optimized",
- "Embed after all optimization passes")),
+ cl::values(
+ clEnumValN(LTOBitcodeEmbedding::DoNotEmbed, "none", "Do not embed"),
+ clEnumValN(LTOBitcodeEmbedding::EmbedOptimized, "optimized",
+ "Embed after all optimization passes"),
+ clEnumValN(LTOBitcodeEmbedding::EmbedPostThinLTOMerge,
+ "post-thinlto-merge",
+ "Embed post thinlto merge, but before optimizations")),
cl::desc("Embed LLVM bitcode in object files produced by LTO"));
LLVM_ATTRIBUTE_NORETURN static void reportOpenError(StringRef Path, Twine Msg) {
@@ -531,7 +537,8 @@
Module &Mod, const ModuleSummaryIndex &CombinedIndex,
const FunctionImporter::ImportMapTy &ImportList,
const GVSummaryMapTy &DefinedGlobals,
- MapVector<StringRef, BitcodeModule> &ModuleMap) {
+ MapVector<StringRef, BitcodeModule> &ModuleMap,
+ const std::vector<uint8_t> *CmdArgs) {
Expected<const Target *> TOrErr = initAndLookupTarget(Conf, Mod);
if (!TOrErr)
return TOrErr.takeError();
@@ -598,6 +605,23 @@
if (Conf.PostImportModuleHook && !Conf.PostImportModuleHook(Task, Mod))
return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
+ if (EmbedBitcode == LTOBitcodeEmbedding::EmbedPostThinLTOMerge) {
+ // FIXME: the motivation for capturing post-merge bitcode and command line
+ // is replicating the compilation environment from bitcode, without needing
+ // to understand the dependencies (the functions to be imported). This
+ // assumes a clang - based invocation, case in which we have the command
+ // line.
+ // It's not very clear how the above motivation would map in the
+ // linker-based case, so we currently don't plumb the command line args in
+ // that case.
+ if (CmdArgs == nullptr)
+ LLVM_DEBUG(
+ dbgs() << "Post-ThinLTO merge bitcode embedding was requested, but "
+ "command line arguments are not available");
+ llvm::EmbedBitcodeInModule(Mod, llvm::MemoryBufferRef(),
+ /*EmbedBitcode*/ true,
+ /*EmbedMarker*/ false, CmdArgs);
+ }
if (!opt(Conf, TM.get(), Task, Mod, /*IsThinLTO=*/true,
/*ExportSummary=*/nullptr, /*ImportSummary=*/&CombinedIndex))
return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
Index: llvm/include/llvm/LTO/LTOBackend.h
===================================================================
--- llvm/include/llvm/LTO/LTOBackend.h
+++ llvm/include/llvm/LTO/LTOBackend.h
@@ -44,7 +44,8 @@
Module &M, const ModuleSummaryIndex &CombinedIndex,
const FunctionImporter::ImportMapTy &ImportList,
const GVSummaryMapTy &DefinedGlobals,
- MapVector<StringRef, BitcodeModule> &ModuleMap);
+ MapVector<StringRef, BitcodeModule> &ModuleMap,
+ const std::vector<uint8_t> *CmdArgs = nullptr);
Error finalizeOptimizationRemarks(
std::unique_ptr<ToolOutputFile> DiagOutputFile);
Index: clang/test/CodeGen/thinlto_embed_bitcode.ll
===================================================================
--- /dev/null
+++ clang/test/CodeGen/thinlto_embed_bitcode.ll
@@ -0,0 +1,30 @@
+; REQUIRES: x86-registered-target
+
+; check the -lto-embed-bitcode=post-thinlto-merge does not perform optimizations
+; we expect 't1' - i.e start-lib1.ll's products - have both foo and bar defined,
+; but the bar call is still made from foo.
+; RUN: opt -module-summary %p/Inputs/start-lib1.ll -o %t1.bc
+; RUN: opt -module-summary %p/Inputs/start-lib2.ll -o %t2.bc
+; RUN: llvm-lto -thinlto -o %t.o %t1.bc %t2.bc
+
+; RUN: %clang -target x86_64-unknown-linux-gnu -O2 -o %t.o -x ir %t1.bc -c -fthinlto-index=%t.o.thinlto.bc -mllvm -lto-embed-bitcode=post-thinlto-merge
+; RUN: llvm-readelf -S %t.o | FileCheck %s --check-prefixes=CHECK-ELF,CHECK-CMD
+; RUN: llvm-objcopy --dump-section=.llvmbc=%t-embedded.bc %t.o /dev/null
+; RUN: llvm-dis %t-embedded.bc -o - | FileCheck %s --check-prefixes=CHECK,CHECK-NOOPT
+
+; For the optimized case, we expect the inlining of foo into bar to happen.
+; RUN: %clang -target x86_64-unknown-linux-gnu -O2 -o %t.o -x ir %t1.bc -c -fthinlto-index=%t.o.thinlto.bc -mllvm -lto-embed-bitcode=optimized
+; RUN: llvm-readelf -S %t.o | FileCheck %s --check-prefixes=CHECK-ELF,CHECK-NO-CMD
+; RUN: llvm-objcopy --dump-section=.llvmbc=%t-embedded.bc %t.o /dev/null
+; RUN: llvm-dis %t-embedded.bc -o - | FileCheck %s --check-prefixes=CHECK,CHECK-OPT
+
+; CHECK-ELF: .text PROGBITS 0000000000000000 [[#%x,OFF:]] [[#%x,SIZE:]] 00 AX 0
+; CHECK-ELF-NEXT: .llvmbc PROGBITS 0000000000000000 [[#%x,OFF:]] [[#%x,SIZE:]] 00 0
+; CHECK-ELF-CMD: .llvmcmd
+; CHECK-ELF-NO-CMD-NOT: .llvmcmd
+
+; CHECK: define void @foo()
+; CHECK-OPT-NEXT: ret void
+; CHECK-NOOPT-NEXT: call void @bar()
+; CHECK-NOOPT: define available_externally void @bar() !thinlto_src_module !0 {
+; CHECK-NOOPT-NEXT: ret void
Index: clang/test/CodeGen/Inputs/start-lib2.ll
===================================================================
--- clang/test/CodeGen/Inputs/start-lib2.ll
+++ clang/test/CodeGen/Inputs/start-lib2.ll
@@ -1,8 +1,6 @@
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
-declare void @bar()
-
-define void @foo() {
+define void @bar() {
ret void
}
Index: llvm/test/LTO/X86/Inputs/start-lib1.ll
===================================================================
--- llvm/test/LTO/X86/Inputs/start-lib1.ll
+++ llvm/test/LTO/X86/Inputs/start-lib1.ll
@@ -4,5 +4,6 @@
declare void @bar()
define void @foo() {
+ call void @bar()
ret void
}
Index: clang/test/CodeGen/Inputs/start-lib1.ll
===================================================================
--- clang/test/CodeGen/Inputs/start-lib1.ll
+++ clang/test/CodeGen/Inputs/start-lib1.ll
@@ -4,5 +4,6 @@
declare void @bar()
define void @foo() {
+ call void @bar()
ret void
}
Index: clang/lib/CodeGen/BackendUtil.cpp
===================================================================
--- clang/lib/CodeGen/BackendUtil.cpp
+++ clang/lib/CodeGen/BackendUtil.cpp
@@ -1646,9 +1646,10 @@
Conf.CGFileType = getCodeGenFileType(Action);
break;
}
- if (Error E = thinBackend(
- Conf, -1, AddStream, *M, *CombinedIndex, ImportList,
- ModuleToDefinedGVSummaries[M->getModuleIdentifier()], ModuleMap)) {
+ if (Error E =
+ thinBackend(Conf, -1, AddStream, *M, *CombinedIndex, ImportList,
+ ModuleToDefinedGVSummaries[M->getModuleIdentifier()],
+ ModuleMap, &CGOpts.CmdArgs)) {
handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
errs() << "Error running ThinLTO backend: " << EIB.message() << '\n';
});
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