The "inner" ``catchswitch`` consumes ``%1`` which is produced by the outer
catchswitch.
+
+.. _wineh-constraints:
+
+Funclet transitions
+-----------------------
+
+The EH tables for personalities that use funclets make implicit use of the
+funclet nesting relationship to encode unwind destinations, and so are
+constrained in the set of funclet transitions they can represent. The related
+LLVM IR instructions accordingly have constraints that ensure encodability of
+the EH edges in the flow graph.
+
+A ``catchswitch``, ``catchpad``, or ``cleanuppad`` is said to be "entered"
+when it executes. It may subsequently be "exited" by any of the following
+means:
+
+* A ``catchswitch`` is immediately exited when none of its constituent
+ ``catchpad``\ s are appropriate for the in-flight exception and it unwinds
+ to its unwind destination or the caller.
+* A ``catchpad`` and its parent ``catchswitch`` are both exited when a
+ ``catchret`` from the ``catchpad`` is executed.
+* A ``cleanuppad`` is exited when a ``cleanupret`` from it is executed.
+* Any of these pads is exited when control unwinds to the function's caller,
+ either by a ``call`` which unwinds all the way to the function's caller,
+ a nested ``catchswitch`` marked "``unwinds to caller``", or a nested
+ ``cleanuppad``\ 's ``cleanupret`` marked "``unwinds to caller"``.
+* Any of these pads is exited when an unwind edge (from an ``invoke``,
+ nested ``catchswitch``, or nested ``cleanuppad``\ 's ``cleanupret``)
+ unwinds to a destination pad that is not a descendant of the given pad.
+
+Note that the ``ret`` instruction is *not* a valid way to exit a funclet pad;
+it is undefined behavior to execute a ``ret`` when a pad has been entered but
+not exited.
+
+A single unwind edge may exit any number of pads (with the restrictions that
+the edge from a ``catchswitch`` must exit at least itself, and the edge from
+a ``cleanupret`` must exit at least its ``cleanuppad``), and then must enter
+exactly one pad, which must be distinct from all the exited pads. The parent
+of the pad that an unwind edge enters must be the most-recently-entered
+not-yet-exited pad (after exiting from any pads that the unwind edge exits),
+or "none" if there is no such pad. This ensures that the stack of executing
+funclets at run-time always corresponds to some path in the funclet pad tree
+that the parent tokens encode.
semantically equivalent to composing the caller's deoptimization
continuation after the callee's deoptimization continuation.
+.. _ob_funclet:
+
Funclet Operand Bundles
^^^^^^^^^^^^^^^^^^^^^^^
``"funclet"`` operand bundle attached to a call site and it must have
exactly one bundle operand.
+If any funclet EH pads have been "entered" but not "exited" (per the
+`description in the EH doc\ <ExceptionHandling.html#wineh-constraints>`_),
+it is undefined behavior to execute a ``call`` or ``invoke`` which:
+
+* does not have a ``"funclet"`` bundle and is not a ``call`` to a nounwind
+ intrinsic, or
+* has a ``"funclet"`` bundle whose operand is not the most-recently-entered
+ not-yet-exited funclet EH pad.
+
+Similarly, if no funclet EH pads have been entered-but-not-yet-exited,
+executing a ``call`` or ``invoke`` with a ``"funclet"`` bundle is undefined behavior.
+
.. _moduleasm:
Module-Level Inline Assembly
``catchswitch`` instruction. If the ``catchswitch`` is not inside a funclet,
this operand may be the token ``none``.
-The ``default`` argument is the label of another basic block beginning with a
-"pad" instruction, one of ``cleanuppad`` or ``catchswitch``.
+The ``default`` argument is the label of another basic block beginning with
+either a ``cleanuppad`` or ``catchswitch`` instruction. This unwind destination
+must be a legal target with respect to the ``parent`` links, as described in
+the `exception handling documentation\ <ExceptionHandling.html#wineh-constraints>`_.
-The ``handlers`` are a list of successor blocks that each begin with a
+The ``handlers`` are a nonempty list of successor blocks that each begin with a
:ref:`catchpad <i_catchpad>` instruction.
Semantics:
The meaning of the tokens produced and consumed by ``catchpad`` and other "pad"
instructions is described in the
-`Windows exception handling documentation <ExceptionHandling.html#wineh>`.
+`Windows exception handling documentation\ <ExceptionHandling.html#wineh>`_.
-Executing a ``catchpad`` instruction constitutes "entering" that pad.
-The pad may then be "exited" in one of three ways:
-
-1) explicitly via a ``catchret`` that consumes it. Executing such a ``catchret``
- is undefined behavior if any descendant pads have been entered but not yet
- exited.
-2) implicitly via a call (which unwinds all the way to the current function's caller),
- or via a ``catchswitch`` or a ``cleanupret`` that unwinds to caller.
-3) implicitly via an unwind edge whose destination EH pad isn't a descendant of
- the ``catchpad``. When the ``catchpad`` is exited in this manner, it is
- undefined behavior if the destination EH pad has a parent which is not an
- ancestor of the ``catchpad`` being exited.
+When a ``catchpad`` has been "entered" but not yet "exited" (as
+described in the `EH documentation\ <ExceptionHandling.html#wineh-constraints>`_),
+it is undefined behavior to execute a :ref:`call <i_call>` or :ref:`invoke <i_invoke>`
+that does not carry an appropriate :ref:`"funclet" bundle <ob_funclet>`.
Example:
""""""""
code to, for example, destroy the active exception. Control then transfers to
``normal``.
-The ``token`` argument must be a token produced by a dominating ``catchpad``
-instruction. The ``catchret`` destroys the physical frame established by
-``catchpad``, so executing multiple returns on the same token without
-re-executing the ``catchpad`` will result in undefined behavior.
-See :ref:`catchpad <i_catchpad>` for more details.
+The ``token`` argument must be a token produced by a ``catchpad`` instruction.
+If the specified ``catchpad`` is not the most-recently-entered not-yet-exited
+funclet pad (as described in the `EH documentation\ <ExceptionHandling.html#wineh-constraints>`_),
+the ``catchret``'s behavior is undefined.
Example:
""""""""
The '``cleanupret``' instruction requires one argument, which indicates
which ``cleanuppad`` it exits, and must be a :ref:`cleanuppad <i_cleanuppad>`.
-It also has an optional successor, ``continue``.
+If the specified ``cleanuppad`` is not the most-recently-entered not-yet-exited
+funclet pad (as described in the `EH documentation\ <ExceptionHandling.html#wineh-constraints>`_),
+the ``cleanupret``'s behavior is undefined.
+
+The '``cleanupret``' instruction also has an optional successor, ``continue``,
+which must be the label of another basic block beginning with either a
+``cleanuppad`` or ``catchswitch`` instruction. This unwind destination must
+be a legal target with respect to the ``parent`` links, as described in the
+`exception handling documentation\ <ExceptionHandling.html#wineh-constraints>`_.
Semantics:
""""""""""
:ref:`cleanuppad <i_cleanuppad>` it transferred control to has ended.
It transfers control to ``continue`` or unwinds out of the function.
-The unwind destination ``continue``, if present, must be an EH pad
-whose parent is either ``none`` or an ancestor of the ``cleanuppad``
-being returned from. This constitutes an exceptional exit from all
-ancestors of the completed ``cleanuppad``, up to but not including
-the parent of ``continue``.
-See :ref:`cleanuppad <i_cleanuppad>` for more details.
-
Example:
""""""""
- A basic block that is not a cleanup block may not include a
'``cleanuppad``' instruction.
-Executing a ``cleanuppad`` instruction constitutes "entering" that pad.
-The pad may then be "exited" in one of three ways:
-
-1) explicitly via a ``cleanupret`` that consumes it. Executing such a ``cleanupret``
- is undefined behavior if any descendant pads have been entered but not yet
- exited.
-2) implicitly via a call (which unwinds all the way to the current function's caller),
- or via a ``catchswitch`` or a ``cleanupret`` that unwinds to caller.
-3) implicitly via an unwind edge whose destination EH pad isn't a descendant of
- the ``cleanuppad``. When the ``cleanuppad`` is exited in this manner, it is
- undefined behavior if the destination EH pad has a parent which is not an
- ancestor of the ``cleanuppad`` being exited.
+When a ``cleanuppad`` has been "entered" but not yet "exited" (as
+described in the `EH documentation\ <ExceptionHandling.html#wineh-constraints>`_),
+it is undefined behavior to execute a :ref:`call <i_call>` or :ref:`invoke <i_invoke>`
+that does not carry an appropriate :ref:`"funclet" bundle <ob_funclet>`.
It is undefined behavior for the ``cleanuppad`` to exit via an unwind edge which
does not transitively unwind to the same destination as a constituent
visitInstruction(IVI);
}
+static Value *getParentPad(Value *EHPad) {
+ if (auto *FPI = dyn_cast<FuncletPadInst>(EHPad))
+ return FPI->getParentPad();
+
+ return cast<CatchSwitchInst>(EHPad)->getParentPad();
+}
+
void Verifier::visitEHPadPredecessors(Instruction &I) {
assert(I.isEHPad());
return;
}
+ // Verify that each pred has a legal terminator with a legal to/from EH
+ // pad relationship.
+ Instruction *ToPad = &I;
+ Value *ToPadParent = getParentPad(ToPad);
for (BasicBlock *PredBB : predecessors(BB)) {
TerminatorInst *TI = PredBB->getTerminator();
+ Value *FromPad;
if (auto *II = dyn_cast<InvokeInst>(TI)) {
Assert(II->getUnwindDest() == BB && II->getNormalDest() != BB,
- "EH pad must be jumped to via an unwind edge", &I, II);
- } else if (!isa<CleanupReturnInst>(TI) && !isa<CatchSwitchInst>(TI)) {
- Assert(false, "EH pad must be jumped to via an unwind edge", &I, TI);
+ "EH pad must be jumped to via an unwind edge", ToPad, II);
+ if (auto Bundle = II->getOperandBundle(LLVMContext::OB_funclet))
+ FromPad = Bundle->Inputs[0];
+ else
+ FromPad = ConstantTokenNone::get(II->getContext());
+ } else if (auto *CRI = dyn_cast<CleanupReturnInst>(TI)) {
+ FromPad = CRI->getCleanupPad();
+ Assert(FromPad != ToPadParent, "A cleanupret must exit its cleanup", CRI);
+ } else if (auto *CSI = dyn_cast<CatchSwitchInst>(TI)) {
+ FromPad = CSI;
+ } else {
+ Assert(false, "EH pad must be jumped to via an unwind edge", ToPad, TI);
+ }
+
+ // The edge may exit from zero or more nested pads.
+ for (;; FromPad = getParentPad(FromPad)) {
+ Assert(FromPad != ToPad,
+ "EH pad cannot handle exceptions raised within it", FromPad, TI);
+ if (FromPad == ToPadParent) {
+ // This is a legal unwind edge.
+ break;
+ }
+ Assert(!isa<ConstantTokenNone>(FromPad),
+ "A single unwind edge may only enter one EH pad", TI);
}
}
}
; CHECK-NEXT: br label %body
body:
- invoke void @f.ccc() to label %continue unwind label %terminate.inner
+ invoke void @f.ccc() [ "funclet"(token %catch) ]
+ to label %continue unwind label %terminate.inner
catchret from %catch to label %return
; CHECK: catchret from %catch to label %return
invoke void @_Z3quxv() optsize
to label %exit unwind label %pad
cleanup:
- cleanupret from %cp unwind label %pad
+ cleanupret from %cp unwind to caller
pad:
%cp = cleanuppad within none []
br label %cleanup
invoke void @_Z3quxv() optsize
to label %exit unwind label %pad
cleanup:
- cleanupret from %0 unwind label %pad
+ cleanupret from %0 unwind to caller
pad:
%0 = cleanuppad within none []
br label %cleanup
; RUN: sed -e s/.T6:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK6 %s
; RUN: sed -e s/.T7:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK7 %s
; RUN: sed -e s/.T8:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK8 %s
+; RUN: sed -e s/.T9:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK9 %s
+; RUN: sed -e s/.T10:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK10 %s
+; RUN: sed -e s/.T11:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK11 %s
+; RUN: sed -e s/.T12:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK12 %s
+; RUN: sed -e s/.T13:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK13 %s
declare void @g()
;T8: %cs1 = catchswitch within none [ label %switch1 ] unwind to caller
;T8: ; CHECK8: CatchSwitchInst handlers must be catchpads
;T8: }
+
+;T9: define void @f() personality void ()* @g {
+;T9: entry:
+;T9: ret void
+;T9: cleanup:
+;T9: %cp = cleanuppad within none []
+;T9: invoke void @g() [ "funclet"(token %cp) ]
+;T9: to label %exit unwind label %cleanup
+;T9: ; CHECK9: EH pad cannot handle exceptions raised within it
+;T9: ; CHECK9-NEXT: %cp = cleanuppad within none []
+;T9: ; CHECK9-NEXT: invoke void @g() [ "funclet"(token %cp) ]
+;T9: exit:
+;T9: ret void
+;T9: }
+
+;T10: define void @f() personality void ()* @g {
+;T10: entry:
+;T10: ret void
+;T10: cleanup1:
+;T10: %cp1 = cleanuppad within none []
+;T10: unreachable
+;T10: switch:
+;T10: %cs = catchswitch within %cp1 [label %catch] unwind to caller
+;T10: catch:
+;T10: %catchp1 = catchpad within %cs [i32 1]
+;T10: unreachable
+;T10: cleanup2:
+;T10: %cp2 = cleanuppad within %catchp1 []
+;T10: unreachable
+;T10: cleanup3:
+;T10: %cp3 = cleanuppad within %cp2 []
+;T10: cleanupret from %cp3 unwind label %switch
+;T10: ; CHECK10: EH pad cannot handle exceptions raised within it
+;T10: ; CHECK10-NEXT: %cs = catchswitch within %cp1 [label %catch] unwind to caller
+;T10: ; CHECK10-NEXT: cleanupret from %cp3 unwind label %switch
+;T10: }
+
+;T11: define void @f() personality void ()* @g {
+;T11: entry:
+;T11: ret void
+;T11: cleanup1:
+;T11: %cp1 = cleanuppad within none []
+;T11: unreachable
+;T11: cleanup2:
+;T11: %cp2 = cleanuppad within %cp1 []
+;T11: unreachable
+;T11: switch:
+;T11: %cs = catchswitch within none [label %catch] unwind label %cleanup2
+;T11: ; CHECK11: A single unwind edge may only enter one EH pad
+;T11: ; CHECK11-NEXT: %cs = catchswitch within none [label %catch] unwind label %cleanup2
+;T11: catch:
+;T11: catchpad within %cs [i32 1]
+;T11: unreachable
+;T11: }
+
+;T12: define void @f() personality void ()* @g {
+;T12: entry:
+;T12: ret void
+;T12: cleanup:
+;T12: %cp = cleanuppad within none []
+;T12: cleanupret from %cp unwind label %switch
+;T12: ; CHECK12: A cleanupret must exit its cleanup
+;T12: ; CHECK12-NEXT: cleanupret from %cp unwind label %switch
+;T12: switch:
+;T12: %cs = catchswitch within %cp [label %catch] unwind to caller
+;T12: catch:
+;T12: catchpad within %cs [i32 1]
+;T12: unreachable
+;T12: }
+
+;T13: define void @f() personality void ()* @g {
+;T13: entry:
+;T13: ret void
+;T13: switch:
+;T13: %cs = catchswitch within none [label %catch] unwind label %switch
+;T13: ; CHECK13: EH pad cannot handle exceptions raised within it
+;T13: ; CHECK13-NEXT: %cs = catchswitch within none [label %catch] unwind label %switch
+;T13: catch:
+;T13: catchpad within %cs [i32 0]
+;T13: unreachable
+;T13: }
+
projects / oota-llvm.git / commitdiff