[CodeView] Teach clang to emit the .debug$H COFF section.
Currently this is an LLVM extension to the COFF spec which is
experimental and intended to speed up linking. For now it is
behind a hidden cl::opt flag, but in the future we can move it
to a "real" cc1 flag and have the driver pass it through whenever
it is appropriate.
The patch to actually make use of this section in lld will come
in a followup.
Differential Revision: https://reviews.llvm.org/D40917
llvm-svn: 320649
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index 4c21593..97b5949 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -67,10 +67,12 @@
#include "llvm/Support/BinaryByteStream.h"
#include "llvm/Support/BinaryStreamReader.h"
#include "llvm/Support/Casting.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/SMLoc.h"
#include "llvm/Support/ScopedPrinter.h"
#include "llvm/Target/TargetMachine.h"
@@ -88,6 +90,9 @@
using namespace llvm;
using namespace llvm::codeview;
+static cl::opt<bool> EmitDebugGlobalHashes("emit-codeview-ghash-section",
+ cl::ReallyHidden, cl::init(false));
+
CodeViewDebug::CodeViewDebug(AsmPrinter *AP)
: DebugHandlerBase(AP), OS(*Asm->OutStreamer), TypeTable(Allocator) {
// If module doesn't have named metadata anchors or COFF debug section
@@ -486,10 +491,13 @@
OS.AddComment("String table");
OS.EmitCVStringTableDirective();
- // Emit type information last, so that any types we translate while emitting
- // function info are included.
+ // Emit type information and hashes last, so that any types we translate while
+ // emitting function info are included.
emitTypeInformation();
+ if (EmitDebugGlobalHashes)
+ emitTypeGlobalHashes();
+
clear();
}
@@ -506,11 +514,6 @@
}
void CodeViewDebug::emitTypeInformation() {
- // Do nothing if we have no debug info or if no non-trivial types were emitted
- // to TypeTable during codegen.
- NamedMDNode *CU_Nodes = MMI->getModule()->getNamedMetadata("llvm.dbg.cu");
- if (!CU_Nodes)
- return;
if (TypeTable.empty())
return;
@@ -555,6 +558,40 @@
}
}
+void CodeViewDebug::emitTypeGlobalHashes() {
+ if (TypeTable.empty())
+ return;
+
+ // Start the .debug$H section with the version and hash algorithm, currently
+ // hardcoded to version 0, SHA1.
+ OS.SwitchSection(Asm->getObjFileLowering().getCOFFGlobalTypeHashesSection());
+
+ OS.EmitValueToAlignment(4);
+ OS.AddComment("Magic");
+ OS.EmitIntValue(COFF::DEBUG_HASHES_SECTION_MAGIC, 4);
+ OS.AddComment("Section Version");
+ OS.EmitIntValue(0, 2);
+ OS.AddComment("Hash Algorithm");
+ OS.EmitIntValue(uint16_t(GlobalTypeHashAlg::SHA1), 2);
+
+ TypeIndex TI(TypeIndex::FirstNonSimpleIndex);
+ for (const auto &GHR : TypeTable.hashes()) {
+ if (OS.isVerboseAsm()) {
+ // Emit an EOL-comment describing which TypeIndex this hash corresponds
+ // to, as well as the stringified SHA1 hash.
+ SmallString<32> Comment;
+ raw_svector_ostream CommentOS(Comment);
+ CommentOS << formatv("{0:X+} [{1}]", TI.getIndex(), GHR);
+ OS.AddComment(Comment);
+ ++TI;
+ }
+ assert(GHR.Hash.size() % 20 == 0);
+ StringRef S(reinterpret_cast<const char *>(GHR.Hash.data()),
+ GHR.Hash.size());
+ OS.EmitBinaryData(S);
+ }
+}
+
static SourceLanguage MapDWLangToCVLang(unsigned DWLang) {
switch (DWLang) {
case dwarf::DW_LANG_C:
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
index 663b9b5..69e9364 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
@@ -23,7 +23,7 @@
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/DebugInfo/CodeView/CodeView.h"
-#include "llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h"
+#include "llvm/DebugInfo/CodeView/GlobalTypeTableBuilder.h"
#include "llvm/DebugInfo/CodeView/TypeIndex.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/Support/Allocator.h"
@@ -52,7 +52,7 @@
class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public DebugHandlerBase {
MCStreamer &OS;
BumpPtrAllocator Allocator;
- codeview::MergingTypeTableBuilder TypeTable;
+ codeview::GlobalTypeTableBuilder TypeTable;
/// Represents the most general definition range.
struct LocalVarDefRange {
@@ -219,6 +219,8 @@
void emitTypeInformation();
+ void emitTypeGlobalHashes();
+
void emitCompilerInformation();
void emitInlineeLinesSubsection();