[clang] 13aee94 - [ThinLTO] Fix empty .llvmcmd sections

[Mircea Trofin via cfe-commits]

Author: Mircea Trofin
Date: 2020-10-29T09:57:42-07:00
New Revision: 13aee94bc710bfa6277c1f07146c714ee65bf2de

URL: https://github.com/llvm/llvm-project/commit/13aee94bc710bfa6277c1f07146c714ee65bf2de
DIFF: https://github.com/llvm/llvm-project/commit/13aee94bc710bfa6277c1f07146c714ee65bf2de.diff

LOG: [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

Added: 
    

Modified: 
    clang/lib/Frontend/CompilerInvocation.cpp
    clang/test/CodeGen/thinlto_embed_bitcode.ll

Removed: 
    


################################################################################
diff  --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 5175063adb02..22579161b345 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -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');
     }
   }
 

diff  --git a/clang/test/CodeGen/thinlto_embed_bitcode.ll b/clang/test/CodeGen/thinlto_embed_bitcode.ll
index 5f7b9f632af3..6c7e36e7226b 100644
--- a/clang/test/CodeGen/thinlto_embed_bitcode.ll
+++ b/clang/test/CodeGen/thinlto_embed_bitcode.ll
@@ -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
+; 
diff erent 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