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[ThinLTO] Fix empty .llvmcmd sections 

When passing -lto-embed-bitcode=post-merge-pre-opt, we were getting
empty .llvmcmd sections. It turns out that is because the
CodeGenOptions::CmdArgs field was only populated when clang saw
-fembed-bitcode={all|marker}.

This patch always populates the CodeGenOptions::CmdArgs. The overhead
of carrying through in memory in all cases is likely negligible in
the grand schema of things, and it keeps the using code simple.

Differential Revision: https://reviews.llvm.org/D90366
This commit is contained in:
Mircea Trofin 2020-10-28 20:16:51 -07:00
parent ec7780ebda
commit 13aee94bc7
2 changed files with 23 additions and 17 deletions
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32
clang/lib/Frontend/CompilerInvocation.cpp
View File

@ -1095,23 +1095,21 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
// FIXME: For backend options that are not yet recorded as function
// attributes in the IR, keep track of them so we can embed them in a
// separate data section and use them when building the bitcode.
if (Opts.getEmbedBitcode() == CodeGenOptions::Embed_All) {
for (const auto &A : Args) {
// Do not encode output and input.
if (A->getOption().getID() == options::OPT_o ||
A->getOption().getID() == options::OPT_INPUT ||
A->getOption().getID() == options::OPT_x ||
A->getOption().getID() == options::OPT_fembed_bitcode ||
A->getOption().matches(options::OPT_W_Group))
continue;
ArgStringList ASL;
A->render(Args, ASL);
for (const auto &arg : ASL) {
StringRef ArgStr(arg);
Opts.CmdArgs.insert(Opts.CmdArgs.end(), ArgStr.begin(), ArgStr.end());
// using \00 to separate each commandline options.
Opts.CmdArgs.push_back('\0');
}
for (const auto &A : Args) {
// Do not encode output and input.
if (A->getOption().getID() == options::OPT_o ||
A->getOption().getID() == options::OPT_INPUT ||
A->getOption().getID() == options::OPT_x ||
A->getOption().getID() == options::OPT_fembed_bitcode ||
A->getOption().matches(options::OPT_W_Group))
continue;
ArgStringList ASL;
A->render(Args, ASL);
for (const auto &arg : ASL) {
StringRef ArgStr(arg);
Opts.CmdArgs.insert(Opts.CmdArgs.end(), ArgStr.begin(), ArgStr.end());
// using \00 to separate each commandline options.
Opts.CmdArgs.push_back('\0');
}
}

8
clang/test/CodeGen/thinlto_embed_bitcode.ll
View File

@ -17,12 +17,20 @@
; round-trip through compilation and ensure the objects are the same.
; 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-merge-pre-opt
; RUN: llvm-readelf -S %t.o | FileCheck %s --check-prefixes=CHECK-ELF,CHECK-ELF-CMD
; RUN: llvm-objcopy --dump-section=.llvmcmd=%t-embedded.cmd %t.o /dev/null
; RUN: grep x86_64-unknown-linux-gnu %t-embedded.cmd | count 1
; 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
; We should only need the index and the post-thinlto merged module to generate
; the exact same .o as we originally did.
; RUN: rm %t1.bc %t2.bc
; RUN: %clang -target x86_64-unknown-linux-gnu -O2 -o %t-redo.o -x ir %t-embedded.bc -c -fthinlto-index=%t.o.thinlto.bc -mllvm -lto-embed-bitcode=post-merge-pre-opt -mllvm -thinlto-assume-merged
;
; The resulting .o is almost the same, but the .llvmcmd section would be
; different because of the extra -thinlto-assume-merged.
; A simple, meaningful comparison is to just compare the stripped objects.
; RUN: llvm-strip --strip-all %t-redo.o
; RUN: llvm-strip --strip-all %t.o
; RUN: diff %t-redo.o %t.o
; CHECK-ELF: .text PROGBITS 0000000000000000 [[#%x,OFF:]] [[#%x,SIZE:]] 00 AX 0