[IR] Reformulate LLVM's EH funclet IR
While we have successfully implemented a funclet-oriented EH scheme on
top of LLVM IR, our scheme has some notable deficiencies:
- catchendpad and cleanupendpad are necessary in the current design
but they are difficult to explain to others, even to seasoned LLVM
experts.
- catchendpad and cleanupendpad are optimization barriers. They cannot
be split and force all potentially throwing call-sites to be invokes.
This has a noticable effect on the quality of our code generation.
- catchpad, while similar in some aspects to invoke, is fairly awkward.
It is unsplittable, starts a funclet, and has control flow to other
funclets.
- The nesting relationship between funclets is currently a property of
control flow edges. Because of this, we are forced to carefully
analyze the flow graph to see if there might potentially exist illegal
nesting among funclets. While we have logic to clone funclets when
they are illegally nested, it would be nicer if we had a
representation which forbade them upfront.
Let's clean this up a bit by doing the following:
- Instead, make catchpad more like cleanuppad and landingpad: no control
flow, just a bunch of simple operands; catchpad would be splittable.
- Introduce catchswitch, a control flow instruction designed to model
the constraints of funclet oriented EH.
- Make funclet scoping explicit by having funclet instructions consume
the token produced by the funclet which contains them.
- Remove catchendpad and cleanupendpad. Their presence can be inferred
implicitly using coloring information.
N.B. The state numbering code for the CLR has been updated but the
veracity of it's output cannot be spoken for. An expert should take a
look to make sure the results are reasonable.
Reviewers: rnk, JosephTremoulet, andrew.w.kaylor
Differential Revision: http://reviews.llvm.org/D15139
llvm-svn: 255422
diff --git a/llvm/test/CodeGen/X86/win32-seh-catchpad.ll b/llvm/test/CodeGen/X86/win32-seh-catchpad.ll
index 4e373af..88dea36 100644
--- a/llvm/test/CodeGen/X86/win32-seh-catchpad.ll
+++ b/llvm/test/CodeGen/X86/win32-seh-catchpad.ll
@@ -11,10 +11,11 @@
to label %invoke.cont unwind label %catch.dispatch
catch.dispatch: ; preds = %entry
- %0 = catchpad [i8* bitcast (i32 ()* @try_except_filter_catchall to i8*)] to label %__except.ret unwind label %catchendblock
+ %cs1 = catchswitch within none [label %__except.ret] unwind to caller
__except.ret: ; preds = %catch.dispatch
- catchret %0 to label %__except
+ %0 = catchpad within %cs1 [i8* bitcast (i32 ()* @try_except_filter_catchall to i8*)]
+ catchret from %0 to label %__except
__except: ; preds = %__except.ret
call void @f(i32 2)
@@ -24,9 +25,6 @@
call void @f(i32 3)
ret void
-catchendblock: ; preds = %catch.dispatch
- catchendpad unwind to caller
-
invoke.cont: ; preds = %entry
br label %__try.cont
}
@@ -77,81 +75,69 @@
to label %__try.cont unwind label %catch.dispatch
catch.dispatch: ; preds = %entry
- %0 = catchpad [i8* bitcast (i32 ()* @nested_exceptions_filter_catchall to i8*)] to label %__except.ret unwind label %catchendblock
+ %cs1 = catchswitch within none [label %__except.ret] unwind label %catch.dispatch.11
__except.ret: ; preds = %catch.dispatch
- catchret %0 to label %__try.cont
+ %0 = catchpad within %cs1 [i8* bitcast (i32 ()* @nested_exceptions_filter_catchall to i8*)]
+ catchret from %0 to label %__try.cont
__try.cont: ; preds = %entry, %__except.ret
invoke void @crash() #3
to label %__try.cont.9 unwind label %catch.dispatch.5
catch.dispatch.5: ; preds = %__try.cont
- %1 = catchpad [i8* bitcast (i32 ()* @nested_exceptions_filter_catchall to i8*)] to label %__except.ret.7 unwind label %catchendblock.6
+ %cs2 = catchswitch within none [label %__except.ret.7] unwind label %catch.dispatch.11
__except.ret.7: ; preds = %catch.dispatch.5
- catchret %1 to label %__try.cont.9
+ %1 = catchpad within %cs2 [i8* bitcast (i32 ()* @nested_exceptions_filter_catchall to i8*)]
+ catchret from %1 to label %__try.cont.9
__try.cont.9: ; preds = %__try.cont, %__except.ret.7
invoke void @crash() #3
to label %__try.cont.15 unwind label %catch.dispatch.11
catch.dispatch.11: ; preds = %catchendblock, %catchendblock.6, %__try.cont.9
- %2 = catchpad [i8* bitcast (i32 ()* @nested_exceptions_filter_catchall to i8*)] to label %__except.ret.13 unwind label %catchendblock.12
+ %cs3 = catchswitch within none [label %__except.ret.13] unwind label %catch.dispatch.17
__except.ret.13: ; preds = %catch.dispatch.11
- catchret %2 to label %__try.cont.15
+ %2 = catchpad within %cs3 [i8* bitcast (i32 ()* @nested_exceptions_filter_catchall to i8*)]
+ catchret from %2 to label %__try.cont.15
__try.cont.15: ; preds = %__try.cont.9, %__except.ret.13
invoke void @crash() #3
to label %__try.cont.35 unwind label %catch.dispatch.17
catch.dispatch.17: ; preds = %catchendblock.12, %__try.cont.15
- %3 = catchpad [i8* bitcast (i32 ()* @nested_exceptions_filter_catchall to i8*)] to label %__except.ret.19 unwind label %catchendblock.18
+ %cs4 = catchswitch within none [label %__except.ret.19] unwind to caller
__except.ret.19: ; preds = %catch.dispatch.17
- catchret %3 to label %__except.20
+ %3 = catchpad within %cs4 [i8* bitcast (i32 ()* @nested_exceptions_filter_catchall to i8*)]
+ catchret from %3 to label %__except.20
__except.20: ; preds = %__except.ret.19
invoke void @crash() #3
to label %__try.cont.27 unwind label %catch.dispatch.23
catch.dispatch.23: ; preds = %__except.20
- %4 = catchpad [i8* bitcast (i32 ()* @nested_exceptions_filter_catchall to i8*)] to label %__except.ret.25 unwind label %catchendblock.24
+ %cs5 = catchswitch within none [label %__except.ret.25] unwind to caller
__except.ret.25: ; preds = %catch.dispatch.23
- catchret %4 to label %__try.cont.27
+ %4 = catchpad within %cs5 [i8* bitcast (i32 ()* @nested_exceptions_filter_catchall to i8*)]
+ catchret from %4 to label %__try.cont.27
__try.cont.27: ; preds = %__except.20, %__except.ret.25
invoke void @crash() #3
to label %__try.cont.35 unwind label %catch.dispatch.30
catch.dispatch.30: ; preds = %__try.cont.27
- %5 = catchpad [i8* bitcast (i32 ()* @nested_exceptions_filter_catchall to i8*)] to label %__except.ret.32 unwind label %catchendblock.31
+ %cs6 = catchswitch within none [label %__except.ret.32] unwind to caller
__except.ret.32: ; preds = %catch.dispatch.30
- catchret %5 to label %__try.cont.35
+ %5 = catchpad within %cs6 [i8* bitcast (i32 ()* @nested_exceptions_filter_catchall to i8*)]
+ catchret from %5 to label %__try.cont.35
__try.cont.35: ; preds = %__try.cont.15, %__try.cont.27, %__except.ret.32
ret void
-
-catchendblock.31: ; preds = %catch.dispatch.30
- catchendpad unwind to caller
-
-catchendblock.24: ; preds = %catch.dispatch.23
- catchendpad unwind to caller
-
-catchendblock.18: ; preds = %catch.dispatch.17
- catchendpad unwind to caller
-
-catchendblock.12: ; preds = %catch.dispatch.11
- catchendpad unwind label %catch.dispatch.17
-
-catchendblock.6: ; preds = %catch.dispatch.5
- catchendpad unwind label %catch.dispatch.11
-
-catchendblock: ; preds = %catch.dispatch
- catchendpad unwind label %catch.dispatch.11
}
; This table is equivalent to the one produced by MSVC, even if it isn't in
@@ -162,19 +148,19 @@
; CHECK: .long -1
; CHECK: .long _nested_exceptions_filter_catchall
; CHECK: .long LBB
-; CHECK: .long -1
+; CHECK: .long 0
+; CHECK: .long _nested_exceptions_filter_catchall
+; CHECK: .long LBB
+; CHECK: .long 1
+; CHECK: .long _nested_exceptions_filter_catchall
+; CHECK: .long LBB
+; CHECK: .long 1
; CHECK: .long _nested_exceptions_filter_catchall
; CHECK: .long LBB
; CHECK: .long -1
; CHECK: .long _nested_exceptions_filter_catchall
; CHECK: .long LBB
-; CHECK: .long 2
-; CHECK: .long _nested_exceptions_filter_catchall
-; CHECK: .long LBB
-; CHECK: .long 3
-; CHECK: .long _nested_exceptions_filter_catchall
-; CHECK: .long LBB
-; CHECK: .long 3
+; CHECK: .long -1
; CHECK: .long _nested_exceptions_filter_catchall
; CHECK: .long LBB
@@ -203,21 +189,19 @@
to label %__except unwind label %catch.dispatch
catch.dispatch: ; preds = %entry
- %0 = catchpad [i8* bitcast (i32 ()* @try_except_filter_catchall to i8*)] to label %__except.ret unwind label %catchendblock
+ %cs1 = catchswitch within none [label %__except.ret] unwind to caller
__except.ret: ; preds = %catch.dispatch
+ %0 = catchpad within %cs1 [i8* bitcast (i32 ()* @try_except_filter_catchall to i8*)]
call void @f(i32 2)
- catchret %0 to label %__except
+ catchret from %0 to label %__except
__except:
ret void
-
-catchendblock: ; preds = %catch.dispatch
- catchendpad unwind to caller
}
; CHECK-LABEL: _code_in_catchpad:
-; CHECK: # %catch.dispatch
+; CHECK: # %__except.ret
; CHECK-NEXT: movl -24(%ebp), %esp
; CHECK-NEXT: addl $12, %ebp
; CHECK-NEXT: movl $-1, -16(%ebp)