[MC] Create unique .pdata sections for every .text section
Summary:
This adds a unique ID to the COFF section uniquing map, similar to the
one we have for ELF. The unique id is not currently exposed via the
assembler because we don't have a use case for it yet. Users generally
create .pdata with the .seh_* family of directives, and the assembler
internally needs to produce .pdata and .xdata sections corresponding to
the code section.
The association between .text sections and the assembler-created .xdata
and .pdata sections is maintained as an ID field of MCSectionCOFF. The
CFI-related sections are created with the given unique ID, so if more
code is added to the same text section, we can find and reuse the CFI
sections that were already created.
Reviewers: majnemer, rafael
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D19376
llvm-svn: 268331
diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index 896318d8..59bbc2e 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -19,8 +19,10 @@
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSection.h"
+#include "llvm/MC/MCSectionCOFF.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCWin64EH.h"
+#include "llvm/Support/COFF.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/raw_ostream.h"
@@ -446,6 +448,7 @@
WinFrameInfos.push_back(new WinEH::FrameInfo(Symbol, StartProc));
CurrentWinFrameInfo = WinFrameInfos.back();
+ CurrentWinFrameInfo->TextSection = getCurrentSectionOnly();
}
void MCStreamer::EmitWinCFIEndProc() {
@@ -467,6 +470,7 @@
WinFrameInfos.push_back(new WinEH::FrameInfo(CurrentWinFrameInfo->Function,
StartProc, CurrentWinFrameInfo));
CurrentWinFrameInfo = WinFrameInfos.back();
+ CurrentWinFrameInfo->TextSection = getCurrentSectionOnly();
}
void MCStreamer::EmitWinCFIEndChained() {
@@ -502,6 +506,38 @@
report_fatal_error("Chained unwind areas can't have handlers!");
}
+static MCSection *getWinCFISection(MCContext &Context, unsigned *NextWinCFIID,
+ MCSection *MainCFISec,
+ const MCSection *TextSec) {
+ // If this is the main .text section, use the main unwind info section.
+ if (TextSec == Context.getObjectFileInfo()->getTextSection())
+ return MainCFISec;
+
+ const auto *TextSecCOFF = cast<MCSectionCOFF>(TextSec);
+ unsigned UniqueID = TextSecCOFF->getOrAssignWinCFISectionID(NextWinCFIID);
+
+ // If this section is COMDAT, this unwind section should be COMDAT associative
+ // with its group.
+ const MCSymbol *KeySym = nullptr;
+ if (TextSecCOFF->getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT)
+ KeySym = TextSecCOFF->getCOMDATSymbol();
+
+ return Context.getAssociativeCOFFSection(cast<MCSectionCOFF>(MainCFISec),
+ KeySym, UniqueID);
+}
+
+MCSection *MCStreamer::getAssociatedPDataSection(const MCSection *TextSec) {
+ return getWinCFISection(getContext(), &NextWinCFIID,
+ getContext().getObjectFileInfo()->getPDataSection(),
+ TextSec);
+}
+
+MCSection *MCStreamer::getAssociatedXDataSection(const MCSection *TextSec) {
+ return getWinCFISection(getContext(), &NextWinCFIID,
+ getContext().getObjectFileInfo()->getXDataSection(),
+ TextSec);
+}
+
void MCStreamer::EmitSyntaxDirective() {}
void MCStreamer::EmitWinCFIPushReg(unsigned Register) {