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author | David Majnemer <david.majnemer@gmail.com> | 2014-06-27 18:19:56 +0000 |
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committer | David Majnemer <david.majnemer@gmail.com> | 2014-06-27 18:19:56 +0000 |
commit | c8a1169c935ad9d3dfbdd4f72d80abf8f5acb03c (patch) | |
tree | ba02374e6ebac3aeaa3c234be27d92c6224cf34f /lib/Bitcode/Writer/BitcodeWriter.cpp | |
parent | 4a295dfbf9c5e8a71b8345484eff200058522b4e (diff) | |
download | llvm-c8a1169c935ad9d3dfbdd4f72d80abf8f5acb03c.tar.gz llvm-c8a1169c935ad9d3dfbdd4f72d80abf8f5acb03c.tar.bz2 llvm-c8a1169c935ad9d3dfbdd4f72d80abf8f5acb03c.tar.xz |
IR: Add COMDATs to the IR
This new IR facility allows us to represent the object-file semantic of
a COMDAT group.
COMDATs allow us to tie together sections and make the inclusion of one
dependent on another. This is required to implement features like MS
ABI VFTables and optimizing away certain kinds of initialization in C++.
This functionality is only representable in COFF and ELF, Mach-O has no
similar mechanism.
Differential Revision: http://reviews.llvm.org/D4178
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211920 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Bitcode/Writer/BitcodeWriter.cpp')
-rw-r--r-- | lib/Bitcode/Writer/BitcodeWriter.cpp | 36 |
1 files changed, 35 insertions, 1 deletions
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp index 3ba7358ae5..dd9282a09e 100644 --- a/lib/Bitcode/Writer/BitcodeWriter.cpp +++ b/lib/Bitcode/Writer/BitcodeWriter.cpp @@ -524,6 +524,35 @@ static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) { llvm_unreachable("Invalid TLS model"); } +static unsigned getEncodedComdatSelectionKind(const Comdat &C) { + switch (C.getSelectionKind()) { + case Comdat::Any: + return bitc::COMDAT_SELECTION_KIND_ANY; + case Comdat::ExactMatch: + return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH; + case Comdat::Largest: + return bitc::COMDAT_SELECTION_KIND_LARGEST; + case Comdat::NoDuplicates: + return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES; + case Comdat::SameSize: + return bitc::COMDAT_SELECTION_KIND_SAME_SIZE; + } + llvm_unreachable("Invalid selection kind"); +} + +static void writeComdats(const ValueEnumerator &VE, BitstreamWriter &Stream) { + SmallVector<uint8_t, 64> Vals; + for (const Comdat *C : VE.getComdats()) { + // COMDAT: [selection_kind, name] + Vals.push_back(getEncodedComdatSelectionKind(*C)); + Vals.push_back(C->getName().size()); + for (char Chr : C->getName()) + Vals.push_back((unsigned char)Chr); + Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0); + Vals.clear(); + } +} + // Emit top-level description of module, including target triple, inline asm, // descriptors for global variables, and function prototype info. static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE, @@ -625,12 +654,14 @@ static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE, if (GV.isThreadLocal() || GV.getVisibility() != GlobalValue::DefaultVisibility || GV.hasUnnamedAddr() || GV.isExternallyInitialized() || - GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass) { + GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass || + GV.hasComdat()) { Vals.push_back(getEncodedVisibility(GV)); Vals.push_back(getEncodedThreadLocalMode(GV)); Vals.push_back(GV.hasUnnamedAddr()); Vals.push_back(GV.isExternallyInitialized()); Vals.push_back(getEncodedDLLStorageClass(GV)); + Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0); } else { AbbrevToUse = SimpleGVarAbbrev; } @@ -656,6 +687,7 @@ static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE, Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1) : 0); Vals.push_back(getEncodedDLLStorageClass(F)); + Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0); unsigned AbbrevToUse = 0; Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse); @@ -1915,6 +1947,8 @@ static void WriteModule(const Module *M, BitstreamWriter &Stream) { // Emit information describing all of the types in the module. WriteTypeTable(VE, Stream); + writeComdats(VE, Stream); + // Emit top-level description of module, including target triple, inline asm, // descriptors for global variables, and function prototype info. WriteModuleInfo(M, VE, Stream); |