tentzen created this revision.
tentzen added reviewers: rnk, eli.friedman, JosephTremoulet, asmith.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
Per Windows SEH Spec, except _leave, all other early exits of a _try
(goto/return/continue/break) are considered abnormal exits. In those cases,
the first parameter passes to its _finally funclet should be TRUE to indicate
an abnormal-termination.
One way to implement abnormal exits in _try is to invoke Windows runtime
_local_unwind() (MSVC approach) that will invoke _dtor funclet where
abnormal-termination flag is always TRUE when calling _finally. Obviously this
approach is less optimal and is complicated to implement in Clang.
Clang today has a NormalCleanupDestSlot mechanism to dispatch multiple exits at
the end of _try. Since _leave (or try-end fall-through) is always Indexed
with 0 in that NormalCleanupDestSlot, this fix takes the advantage of that
mechanism and just passes NormalCleanupDest ID as 1st Arg to _finally.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D77936
Files:
clang/lib/CodeGen/CGCleanup.cpp
clang/lib/CodeGen/CGException.cpp
clang/lib/CodeGen/EHScopeStack.h
Index: clang/lib/CodeGen/EHScopeStack.h
===================================================================
--- clang/lib/CodeGen/EHScopeStack.h
+++ clang/lib/CodeGen/EHScopeStack.h
@@ -160,7 +160,8 @@
enum {
F_IsForEH = 0x1,
F_IsNormalCleanupKind = 0x2,
- F_IsEHCleanupKind = 0x4
+ F_IsEHCleanupKind = 0x4,
+ F_HasSehAbnormalExits = 0x8
};
unsigned flags;
@@ -179,6 +180,9 @@
/// cleanup.
bool isEHCleanupKind() const { return flags & F_IsEHCleanupKind; }
void setIsEHCleanupKind() { flags |= F_IsEHCleanupKind; }
+
+ bool hasSehAbnormalExits() const { return flags & F_HasSehAbnormalExits;
}
+ void setHasSehAbnormalExits() { flags |= F_HasSehAbnormalExits; }
};
Index: clang/lib/CodeGen/CGException.cpp
===================================================================
--- clang/lib/CodeGen/CGException.cpp
+++ clang/lib/CodeGen/CGException.cpp
@@ -1639,6 +1639,18 @@
llvm::Value *IsForEH =
llvm::ConstantInt::get(CGF.ConvertType(ArgTys[0]), F.isForEHCleanup());
+
+ // Except _leave and fall-through at the end, all other exits in a _try
+ // (return/goto/continue/break) are considered as abnormal terminations
+ // since _leave/fall-through is always Indexed 0,
+ // just use NormalCleanupDestSlot (>= 1 for goto/return/..),
+ // as 1st Arg to indicate abnormal termination
+ if (!F.isForEHCleanup() && F.hasSehAbnormalExits()) {
+ Address Addr = CGF.getNormalCleanupDestSlot();
+ llvm::Value* Load = CGF.Builder.CreateLoad(Addr, "cleanup.dest");
+ IsForEH = CGF.Builder.CreateTrunc(Load, CGM.Int8Ty);
+ }
+
Args.add(RValue::get(IsForEH), ArgTys[0]);
Args.add(RValue::get(FP), ArgTys[1]);
Index: clang/lib/CodeGen/CGCleanup.cpp
===================================================================
--- clang/lib/CodeGen/CGCleanup.cpp
+++ clang/lib/CodeGen/CGCleanup.cpp
@@ -860,6 +860,9 @@
// TODO: base this on the number of branch-afters and fixups
const unsigned SwitchCapacity = 10;
+ // pass the abnormal exit flag to Fn (SEH cleanup)
+ cleanupFlags.setHasSehAbnormalExits();
+
llvm::LoadInst *Load =
createLoadInstBefore(getNormalCleanupDestSlot(), "cleanup.dest",
nullptr);
Index: clang/lib/CodeGen/EHScopeStack.h
===================================================================
--- clang/lib/CodeGen/EHScopeStack.h
+++ clang/lib/CodeGen/EHScopeStack.h
@@ -160,7 +160,8 @@
enum {
F_IsForEH = 0x1,
F_IsNormalCleanupKind = 0x2,
- F_IsEHCleanupKind = 0x4
+ F_IsEHCleanupKind = 0x4,
+ F_HasSehAbnormalExits = 0x8
};
unsigned flags;
@@ -179,6 +180,9 @@
/// cleanup.
bool isEHCleanupKind() const { return flags & F_IsEHCleanupKind; }
void setIsEHCleanupKind() { flags |= F_IsEHCleanupKind; }
+
+ bool hasSehAbnormalExits() const { return flags & F_HasSehAbnormalExits; }
+ void setHasSehAbnormalExits() { flags |= F_HasSehAbnormalExits; }
};
Index: clang/lib/CodeGen/CGException.cpp
===================================================================
--- clang/lib/CodeGen/CGException.cpp
+++ clang/lib/CodeGen/CGException.cpp
@@ -1639,6 +1639,18 @@
llvm::Value *IsForEH =
llvm::ConstantInt::get(CGF.ConvertType(ArgTys[0]), F.isForEHCleanup());
+
+ // Except _leave and fall-through at the end, all other exits in a _try
+ // (return/goto/continue/break) are considered as abnormal terminations
+ // since _leave/fall-through is always Indexed 0,
+ // just use NormalCleanupDestSlot (>= 1 for goto/return/..),
+ // as 1st Arg to indicate abnormal termination
+ if (!F.isForEHCleanup() && F.hasSehAbnormalExits()) {
+ Address Addr = CGF.getNormalCleanupDestSlot();
+ llvm::Value* Load = CGF.Builder.CreateLoad(Addr, "cleanup.dest");
+ IsForEH = CGF.Builder.CreateTrunc(Load, CGM.Int8Ty);
+ }
+
Args.add(RValue::get(IsForEH), ArgTys[0]);
Args.add(RValue::get(FP), ArgTys[1]);
Index: clang/lib/CodeGen/CGCleanup.cpp
===================================================================
--- clang/lib/CodeGen/CGCleanup.cpp
+++ clang/lib/CodeGen/CGCleanup.cpp
@@ -860,6 +860,9 @@
// TODO: base this on the number of branch-afters and fixups
const unsigned SwitchCapacity = 10;
+ // pass the abnormal exit flag to Fn (SEH cleanup)
+ cleanupFlags.setHasSehAbnormalExits();
+
llvm::LoadInst *Load =
createLoadInstBefore(getNormalCleanupDestSlot(), "cleanup.dest",
nullptr);
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