Validated by nightly-test runs on x86 and x86-64 darwin, including after

self-host.  Hopefully these results hold up on different platforms.  

I tried to keep the GNU ObjC runtime happy, but it's hard for me to test.
Reimplement how clang generates IR for exceptions.  Instead of creating new
invoke destinations which sequentially chain to the previous destination,
push a more semantic representation of *why* we need the cleanup/catch/filter
behavior, then collect that information into a single landing pad upon request.

Also reorganizes how normal cleanups (i.e. cleanups triggered by non-exceptional
control flow) are generated, since it's actually fairly closely tied in with
the former.  Remove the need to track which cleanup scope a block is associated
with.

Document a lot of previously poorly-understood (by me, at least) behavior.

The new framework implements the Horrible Hack (tm), which requires every
landing pad to have a catch-all so that inlining will work.  Clang no longer
requires the Horrible Hack just to make exceptions flow correctly within
a function, however.  The HH is an unfortunate requirement of LLVM's EH IR.

llvm-svn: 107631

1 files changed, 68 insertions, 19 deletions

diff --git a/clang/test/CodeGenCXX/nrvo.cpp b/clang/test/CodeGenCXX/nrvo.cpp
index 9ee553673f1..6181f0eee13 100644
--- a/clang/test/CodeGenCXX/nrvo.cpp
+++ b/clang/test/CodeGenCXX/nrvo.cpp
@@ -1,5 +1,5 @@
 // RUN: %clang_cc1 -emit-llvm -O1 -o - %s | FileCheck %s
-// RUN: %clang_cc1 -emit-llvm -fexceptions -o - %s | FileCheck --check-prefix=CHECK-EH %s
+// RUN: %clang_cc1 -emit-llvm -O1 -fexceptions -o - %s | FileCheck --check-prefix=CHECK-EH %s
 
 // Test code generation for the named return value optimization.
 class X {
@@ -13,48 +13,97 @@ public:
 // CHECK-EH: define void @_Z5test0v
 X test0() {
   X x;
-  // CHECK-NOT: call void @_ZN1XD1Ev
-  // CHECK: ret void
-  // CHECK-EH: br label
-  // CHECK-EH: call void @_ZN1XD1Ev
-  // CHECK-EH: br label
-  // CHECK-EH: invoke void @_ZN1XD1Ev
-  // CHECK-EH: ret void
+  // CHECK:          call void @_ZN1XC1Ev
+  // CHECK-NEXT:     ret void
+
+  // CHECK-EH:       call void @_ZN1XC1Ev
+  // CHECK-EH-NEXT:  ret void
   return x;
 }
 
 // CHECK: define void @_Z5test1b(
+// CHECK-EH: define void @_Z5test1b(
 X test1(bool B) {
-  // CHECK: call void @_ZN1XC1Ev
+  // CHECK:      tail call void @_ZN1XC1Ev
+  // CHECK-NEXT: ret void
   X x;
-  // CHECK-NOT: call void @_ZN1XD1Ev
-  // CHECK: ret void
   if (B)
     return (x);
   return x;
-  // CHECK-EH: invoke void @_ZN1XD1Ev
+  // CHECK-EH:      tail call void @_ZN1XC1Ev
+  // CHECK-EH-NEXT: ret void
 }
 
 // CHECK: define void @_Z5test2b
 // CHECK-EH: define void @_Z5test2b
 X test2(bool B) {
-  // No NRVO
-  // CHECK: call void @_ZN1XC1Ev
+  // No NRVO.
+
   X x;
-  // CHECK: call void @_ZN1XC1Ev
   X y;
-  // CHECK: call void @_ZN1XC1ERKS_
-  // CHECK-EH: invoke void @_ZN1XC1ERKS_
   if (B)
     return y;
-  // CHECK: call void @_ZN1XC1ERKS_
-  // CHECK-EH: invoke void @_ZN1XC1ERKS_
   return x;
+
+  // CHECK: call void @_ZN1XC1Ev
+  // CHECK-NEXT: call void @_ZN1XC1Ev
+  // CHECK: call void @_ZN1XC1ERKS_
+  // CHECK: call void @_ZN1XC1ERKS_
   // CHECK: call void @_ZN1XD1Ev
   // CHECK: call void @_ZN1XD1Ev
   // CHECK: ret void
+
+  // The block ordering in the -fexceptions IR is unfortunate.
+
+  // CHECK-EH:      call void @_ZN1XC1Ev
+  // CHECK-EH-NEXT: invoke void @_ZN1XC1Ev
+  // -> %invoke.cont1, %lpad
+
+  // %invoke.cont1:
+  // CHECK-EH:      br i1
+  // -> %if.then, %if.end
+
+  // %if.then: returning 'x'
+  // CHECK-EH:      invoke void @_ZN1XC1ERKS_
+  // -> %cleanup, %lpad5
+
+  // %invoke.cont: rethrow block for %eh.cleanup.
+  // This really should be elsewhere in the function.
+  // CHECK-EH:      call void @_Unwind_Resume_or_Rethrow
+  // CHECK-EH-NEXT: unreachable
+
+  // %lpad: landing pad for ctor of 'y', dtor of 'y'
+  // CHECK-EH:      call i8* @llvm.eh.exception()
+  // CHECK-EH: call i32 (i8*, i8*, ...)* @llvm.eh.selector
+  // CHECK-EH-NEXT: br label
+  // -> %eh.cleanup
+
+  // %invoke.cont2: normal cleanup for 'x'
+  // CHECK-EH:      call void @_ZN1XD1Ev
+  // CHECK-EH-NEXT: ret void
+
+  // %lpad5: landing pad for return copy ctors, EH cleanup for 'y'
+  // CHECK-EH: invoke void @_ZN1XD1Ev
+  // -> %eh.cleanup, %terminate.lpad
+
+  // %if.end: returning 'y'
+  // CHECK-EH: invoke void @_ZN1XC1ERKS_
+  // -> %cleanup, %lpad5
+
+  // %cleanup: normal cleanup for 'y'
   // CHECK-EH: invoke void @_ZN1XD1Ev
+  // -> %invoke.cont2, %lpad
+
+  // %eh.cleanup:  EH cleanup for 'x'
   // CHECK-EH: invoke void @_ZN1XD1Ev
+  // -> %invoke.cont, %terminate.lpad
+
+  // %terminate.lpad: terminate landing pad.
+  // CHECK-EH:      call i8* @llvm.eh.exception()
+  // CHECK-EH-NEXT: call i32 (i8*, i8*, ...)* @llvm.eh.selector
+  // CHECK-EH-NEXT: call void @_ZSt9terminatev()
+  // CHECK-EH-NEXT: unreachable
+
 }
 
 X test3(bool B) {