CodeGen support for x86_64 SEH catch handlers in LLVM
This adds handling for ExceptionHandling::MSVC, used by the
x86_64-pc-windows-msvc triple. It assumes that filter functions have
already been outlined in either the frontend or the backend. Filter
functions are used in place of the landingpad catch clause type info
operands. In catch clause order, the first filter to return true will
catch the exception.
The C specific handler table expects the landing pad to be split into
one block per handler, but LLVM IR uses a single landing pad for all
possible unwind actions. This patch papers over the mismatch by
synthesizing single instruction BBs for every catch clause to fill in
the EH selector that the landing pad block expects.
Missing functionality:
- Accessing data in the parent frame from outlined filters
- Cleanups (from __finally) are unsupported, as they will require
outlining and parent frame access
- Filter clauses are unsupported, as there's no clear analogue in SEH
In other words, this is the minimal set of changes needed to write IR to
catch arbitrary exceptions and resume normal execution.
Reviewers: majnemer
Differential Revision: http://reviews.llvm.org/D6300
llvm-svn: 225904
diff --git a/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp b/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
index f112120..1bc86f6 100644
--- a/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
@@ -121,7 +121,8 @@
for (unsigned J = NumShared, M = TypeIds.size(); J != M; ++J) {
int TypeID = TypeIds[J];
assert(-1 - TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
- int ValueForTypeID = TypeID < 0 ? FilterOffsets[-1 - TypeID] : TypeID;
+ int ValueForTypeID =
+ isFilterEHSelector(TypeID) ? FilterOffsets[-1 - TypeID] : TypeID;
unsigned SizeTypeID = getSLEB128Size(ValueForTypeID);
int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
@@ -269,14 +270,14 @@
CallSiteEntry Site = {
BeginLabel,
LastLabel,
- LandingPad->LandingPadLabel,
+ LandingPad,
FirstActions[P.PadIndex]
};
// Try to merge with the previous call-site. SJLJ doesn't do this
if (PreviousIsInvoke && !IsSJLJ) {
CallSiteEntry &Prev = CallSites.back();
- if (Site.PadLabel == Prev.PadLabel && Site.Action == Prev.Action) {
+ if (Site.LPad == Prev.LPad && Site.Action == Prev.Action) {
// Extend the range of the previous entry.
Prev.EndLabel = Site.EndLabel;
continue;
@@ -576,15 +577,15 @@
// Offset of the landing pad, counted in 16-byte bundles relative to the
// @LPStart address.
- if (!S.PadLabel) {
+ if (!S.LPad) {
if (VerboseAsm)
Asm->OutStreamer.AddComment(" has no landing pad");
Asm->OutStreamer.EmitIntValue(0, 4/*size*/);
} else {
if (VerboseAsm)
Asm->OutStreamer.AddComment(Twine(" jumps to ") +
- S.PadLabel->getName());
- Asm->EmitLabelDifference(S.PadLabel, EHFuncBeginSym, 4);
+ S.LPad->LandingPadLabel->getName());
+ Asm->EmitLabelDifference(S.LPad->LandingPadLabel, EHFuncBeginSym, 4);
}
// Offset of the first associated action record, relative to the start of
@@ -681,7 +682,7 @@
unsigned TypeID = *I;
if (VerboseAsm) {
--Entry;
- if (TypeID != 0)
+ if (isFilterEHSelector(TypeID))
Asm->OutStreamer.AddComment("FilterInfo " + Twine(Entry));
}