[Windows SEH] Fix abnormal-exits in _try
Summary:
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.
Reviewers: rnk, eli.friedman, JosephTremoulet, asmith, efriedma
Reviewed By: efriedma
Subscribers: efriedma, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D77936
diff --git a/clang/lib/CodeGen/EHScopeStack.h b/clang/lib/CodeGen/EHScopeStack.h
index 0ed67aa..0fa0b54 100644
--- a/clang/lib/CodeGen/EHScopeStack.h
+++ b/clang/lib/CodeGen/EHScopeStack.h
@@ -158,9 +158,10 @@
/// Generation flags.
class Flags {
enum {
- F_IsForEH = 0x1,
+ F_IsForEH = 0x1,
F_IsNormalCleanupKind = 0x2,
- F_IsEHCleanupKind = 0x4
+ F_IsEHCleanupKind = 0x4,
+ F_HasExitSwitch = 0x8,
};
unsigned flags;
@@ -179,8 +180,10 @@
/// cleanup.
bool isEHCleanupKind() const { return flags & F_IsEHCleanupKind; }
void setIsEHCleanupKind() { flags |= F_IsEHCleanupKind; }
- };
+ bool hasExitSwitch() const { return flags & F_HasExitSwitch; }
+ void setHasExitSwitch() { flags |= F_HasExitSwitch; }
+ };
/// Emit the cleanup. For normal cleanups, this is run in the
/// same EH context as when the cleanup was pushed, i.e. the