outlined. After the handler is outlined, this intrinsic is simply removed.
+.. _llvm.eh.exceptionpointer:
+
+``llvm.eh.exceptionpointer``
+----------------------------
+
+.. code-block:: llvm
+
+ i8 addrspace(N)* @llvm.eh.padparam.pNi8(token %catchpad)
+
+
+This intrinsic retrieves a pointer to the exception caught by the given
+``catchpad``.
+
+
SJLJ Intrinsics
---------------
a ``noexcept`` function should transitively unwind to a terminateblock. Throw
specifications are not implemented by MSVC, and are not yet supported.
-Each of these new EH pad instructions has a label operand that indicates which
+New instructions are also used to mark the points where control is transferred
+out of a catch/cleanup handler (which will correspond to exits from the
+generated funclet). A catch handler which reaches its end by normal execution
+executes a ``catchret`` instruction, which is a terminator indicating where in
+the function control is returned to. A cleanup handler which reaches its end
+by normal execution executes a ``cleanupret`` instruction, which is a terminator
+indicating where the active exception will unwind to next. A catch or cleanup
+handler which is exited by another exception being raised during its execution will
+unwind through a ``catchendpad`` or ``cleanuupendpad`` (respectively). The
+``catchendpad`` and ``cleanupendpad`` instructions are considered "exception
+handling pads" in the same sense that ``catchpad``, ``cleanuppad``, and
+``terminatepad`` are.
+
+Each of these new EH pad instructions has a way to identify which
action should be considered after this action. The ``catchpad`` and
-``terminatepad`` instructions are terminators, and this label is considered to
-be an unwind destination analogous to the unwind destination of an invoke. The
+``terminatepad`` instructions are terminators, and have a label operand considered
+to be an unwind destination analogous to the unwind destination of an invoke. The
``cleanuppad`` instruction is different from the other two in that it is not a
-terminator, and this label operand is not an edge in the CFG. The code inside a
-cleanuppad runs before transferring control to the next action, so the
-``cleanupret`` instruction is the instruction that unwinds to the next EH pad.
-All of these "unwind edges" may refer to a basic block that contains an EH pad
-instruction, or they may simply unwind to the caller. Unwinding to the caller
-has roughly the same semantics as the ``resume`` instruction in the
-``landingpad`` model. When inlining through an invoke, instructions that unwind
-to the caller are hooked up to unwind to the unwind destination of the call
-site.
+terminator. The code inside a cleanuppad runs before transferring control to the
+next action, so the ``cleanupret`` and ``cleanupendpad`` instructions are the
+instructions that hold a label operand and unwind to the next EH pad. All of
+these "unwind edges" may refer to a basic block that contains an EH pad instruction,
+or they may simply unwind to the caller. Unwinding to the caller has roughly the
+same semantics as the ``resume`` instruction in the ``landingpad`` model. When
+inlining through an invoke, instructions that unwind to the caller are hooked
+up to unwind to the unwind destination of the call site.
Putting things together, here is a hypothetical lowering of some C++ that uses
all of the new IR instructions:
Cleanup obj;
may_throw();
} catch (int e) {
+ may_throw();
return e;
}
return 0;
call void @"\01??_DCleanup@@QEAA@XZ"(%struct.Cleanup* nonnull %obj) nounwind
br label %return
- return: ; preds = %invoke.cont.2, %catch
+ return: ; preds = %invoke.cont.2, %invoke.cont.3
%retval.0 = phi i32 [ 0, %invoke.cont.2 ], [ %9, %catch ]
ret i32 %retval.0
; EH scope code, ordered innermost to outermost:
lpad.cleanup: ; preds = %invoke.cont
- cleanuppad [label %lpad.catch]
+ %cleanup = cleanuppad []
call void @"\01??_DCleanup@@QEAA@XZ"(%struct.Cleanup* nonnull %obj) nounwind
- cleanupret unwind label %lpad.catch
+ cleanupret %cleanup unwind label %lpad.catch
lpad.catch: ; preds = %entry, %lpad.cleanup
- catchpad void [%rtti.TypeDescriptor2* @"\01??_R0H@8", i32 0, i32* %e]
- to label %catch unwind label %lpad.terminate
+ %catch = catchpad [%rtti.TypeDescriptor2* @"\01??_R0H@8", i32 0, i32* %e]
+ to label %catch.body unwind label %catchend
- catch: ; preds = %lpad.catch
+ catch.body: ; preds = %lpad.catch
+ invoke void @"\01?may_throw@@YAXXZ"()
+ to label %invoke.cont.3 unwind label %catchend
+
+ invoke.cont.3: ; preds = %catch.body
%9 = load i32, i32* %e, align 4
- catchret label %return
+ catchret %catch label %return
+
+ catchend: ; preds = %lpad.catch, %catch.body
+ catchendpad unwind label %lpad.terminate
- lpad.terminate:
+ lpad.terminate: ; preds = %catchend
terminatepad [void ()* @"\01?terminate@@YAXXZ"]
unwind to caller
}
projects / oota-llvm.git / blobdiff