Set alignment of .llvmbc and .llvmcmd to 1

Otherwise their alignment is dependent on the size of the section.  If the size
is large than 16, the alignment will be 16.

16 is a bad choice for both .llvmbc and .llvmcmd because the padding between two
contributions from input sections is of a variable size.

A bitstream is actually guaranteed to be 4-byte aligned, but consumers don't
need this property.

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index f263090..eaea026 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -4852,6 +4852,9 @@ void llvm::EmbedBitcodeInModule(llvm::Module &M, llvm::MemoryBufferRef Buf,
       M, ModuleConstant->getType(), true, llvm::GlobalValue::PrivateLinkage,
       ModuleConstant);
   GV->setSection(getSectionNameForBitcode(T));
+  // Set alignment to 1 to prevent padding between two contributions from input
+  // sections after linking.
+  GV->setAlignment(Align(1));
   UsedArray.push_back(
       ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
   if (llvm::GlobalVariable *Old =
@@ -4875,6 +4878,7 @@ void llvm::EmbedBitcodeInModule(llvm::Module &M, llvm::MemoryBufferRef Buf,
                                   llvm::GlobalValue::PrivateLinkage,
                                   CmdConstant);
     GV->setSection(getSectionNameForCommandline(T));
+    GV->setAlignment(Align(1));
     UsedArray.push_back(
         ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
     if (llvm::GlobalVariable *Old = M.getGlobalVariable("llvm.cmdline", true)) {