[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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255422 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 51 insertions, 55 deletions

diff --git a/test/Bitcode/compatibility.ll b/test/Bitcode/compatibility.ll
index 6c08a930209..e2a18ebe131 100644
--- a/test/Bitcode/compatibility.ll
+++ b/test/Bitcode/compatibility.ll
@@ -769,95 +769,91 @@ define i32 @instructions.win_eh.1() personality i32 -3 {
 entry:
   %arg1 = alloca i32
   %arg2 = alloca i32
-  invoke void @f.ccc() to label %normal unwind label %catchpad1
-  invoke void @f.ccc() to label %normal unwind label %catchpad2
-  invoke void @f.ccc() to label %normal unwind label %catchpad3
+  invoke void @f.ccc() to label %normal unwind label %catchswitch1
+  invoke void @f.ccc() to label %normal unwind label %catchswitch2
+  invoke void @f.ccc() to label %normal unwind label %catchswitch3
+
+catchswitch1:
+  %cs1 = catchswitch within none [label %catchpad1] unwind label %terminate.1
 
 catchpad1:
-  catchpad [] to label %normal unwind label %exn.1
-  ; CHECK: catchpad []
-  ; CHECK-NEXT: to label %normal unwind label %exn.1
+  catchpad within %cs1 []
+  br label %normal
+  ; CHECK: catchpad within %cs1 []
+  ; CHECK-NEXT: br label %normal
 
-catchpad2:
-  catchpad [i32* %arg1] to label %normal unwind label %exn.2
-  ; CHECK: catchpad [i32* %arg1]
-  ; CHECK-NEXT: to label %normal unwind label %exn.2
+catchswitch2:
+  %cs2 = catchswitch within none [label %catchpad2] unwind to caller
 
-catchpad3:
-  catchpad [i32* %arg1, i32* %arg2] to label %normal unwind label %exn.3
-  ; CHECK: catchpad [i32* %arg1, i32* %arg2] 
-  ; CHECK-NEXT: to label %normal unwind label %exn.3
-
-exn.1:
-  catchendpad unwind label %terminate.1
-  ; CHECK: catchendpad unwind label %terminate.1
+catchpad2:
+  catchpad within %cs2 [i32* %arg1]
+  br label %normal
+  ; CHECK: catchpad within %cs2 [i32* %arg1]
+  ; CHECK-NEXT: br label %normal
 
-exn.2:
-  catchendpad unwind to caller
-  ; CHECK: catchendpad unwind to caller
+catchswitch3:
+  %cs3 = catchswitch within none [label %catchpad3] unwind label %cleanuppad1
 
-exn.3:
-  catchendpad unwind label %cleanuppad1
-  ; CHECK: catchendpad unwind label %cleanuppad1
+catchpad3:
+  catchpad within %cs3 [i32* %arg1, i32* %arg2]
+  br label %normal
+  ; CHECK: catchpad within %cs3 [i32* %arg1, i32* %arg2]
+  ; CHECK-NEXT: br label %normal
 
 cleanuppad1:
-  %clean.1 = cleanuppad []
-  ; CHECK: %clean.1 = cleanuppad []
-  invoke void @f.ccc() to label %normal unwind label %cleanupendpad1
-
-cleanupendpad1:
-  cleanupendpad %clean.1 unwind label %terminate.2
-  ; CHECK: cleanupendpad %clean.1 unwind label %terminate.2
+  %clean.1 = cleanuppad within none []
+  ; CHECK: %clean.1 = cleanuppad within none []
+  invoke void @f.ccc() to label %normal unwind label %terminate.2
 
 terminate.1:
-  terminatepad [] unwind to caller
-  ; CHECK: terminatepad [] unwind to caller
+  terminatepad within none [] unwind to caller
+  ; CHECK: terminatepad within none [] unwind to caller
 
 terminate.2:
-  terminatepad [i32* %arg1] unwind label %normal.pre
-  ; CHECK: terminatepad [i32* %arg1] unwind label %normal.pre
+  terminatepad within %clean.1 [i32* %arg1] unwind label %normal.pre
+  ; CHECK: terminatepad within %clean.1 [i32* %arg1] unwind label %normal.pre
 
 normal.pre:
-  terminatepad [i32* %arg1, i32* %arg2] unwind to caller
-  ; CHECK: terminatepad [i32* %arg1, i32* %arg2] unwind to caller
+  terminatepad within %clean.1 [i32* %arg1, i32* %arg2] unwind to caller
+  ; CHECK: terminatepad within %clean.1 [i32* %arg1, i32* %arg2] unwind to caller
 
 normal:
   ret i32 0
 }
-
+;
 define i32 @instructions.win_eh.2() personality i32 -4 {
 entry:
-  invoke void @f.ccc() to label %invoke.cont unwind label %catchpad
+  invoke void @f.ccc() to label %invoke.cont unwind label %catchswitch
 
 invoke.cont:
   invoke void @f.ccc() to label %continue unwind label %cleanup
 
 cleanup:
-  %clean = cleanuppad []
-  ; CHECK: %clean = cleanuppad []
-  cleanupret %clean unwind to caller
-  ; CHECK: cleanupret %clean unwind to caller
+  %clean = cleanuppad within none []
+  ; CHECK: %clean = cleanuppad within none []
+  cleanupret from %clean unwind to caller
+  ; CHECK: cleanupret from %clean unwind to caller
+
+catchswitch:
+  %cs = catchswitch within none [label %catchpad] unwind label %terminate
 
 catchpad:
-  %catch = catchpad [] to label %body unwind label %catchend
-  ; CHECK: %catch = catchpad []
-  ; CHECK-NEXT: to label %body unwind label %catchend
+  %catch = catchpad within %cs []
+  br label %body
+  ; CHECK: %catch = catchpad within %cs []
+  ; CHECK-NEXT: br label %body
 
 body:
-  invoke void @f.ccc() to label %continue unwind label %catchend
-  catchret %catch to label %return
-  ; CHECK: catchret %catch to label %return
+  invoke void @f.ccc() to label %continue unwind label %terminate
+  catchret from %catch to label %return
+  ; CHECK: catchret from %catch to label %return
 
 return:
   ret i32 0
 
-catchend:
-  catchendpad unwind label %terminate
-  ; CHECK: catchendpad unwind label %terminate
-
 terminate:
-  terminatepad [] unwind to caller
-  ; CHECK: terminatepad [] unwind to caller
+  terminatepad within %cs [] unwind to caller
+  ; CHECK: terminatepad within %cs [] unwind to caller
 
 continue:
   ret i32 0