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bf189bdcd7
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
96 lines
2.5 KiB
LLVM
96 lines
2.5 KiB
LLVM
; RUN: llc -mtriple=x86_64-pc-windows-msvc < %s | FileCheck %s
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declare i32 @__CxxFrameHandler3(...)
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declare void @throw()
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declare i16 @f()
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define i16 @test1(i16 %a, i8* %b) personality i8* bitcast (i32 (...)* @__CxxFrameHandler3 to i8*) {
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entry:
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%cmp = icmp eq i16 %a, 10
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br i1 %cmp, label %if.then, label %if.else
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if.then:
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%call1 = invoke i16 @f()
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to label %cleanup unwind label %catch.dispatch
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if.else:
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%call2 = invoke i16 @f()
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to label %cleanup unwind label %catch.dispatch
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catch.dispatch:
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%cs = catchswitch within none [ label %catch, label %catch.2 ] unwind to caller
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catch:
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catchpad within %cs [i8* null, i32 8, i8* null]
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call void @throw() noreturn
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br label %unreachable
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catch.2:
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catchpad within %cs [i8* null, i32 64, i8* null]
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store i8 1, i8* %b
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call void @throw() noreturn
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br label %unreachable
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cleanup:
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%retval = phi i16 [ %call1, %if.then ], [ %call2, %if.else ]
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ret i16 %retval
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unreachable:
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unreachable
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}
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; This test verifies the case where two funclet blocks meet the old criteria
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; to be placed at the end. The order of the blocks is not important for the
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; purposes of this test. The failure mode is an infinite loop during
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; compilation.
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;
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; CHECK-LABEL: .def test1;
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define i16 @test2(i16 %a, i8* %b) personality i8* bitcast (i32 (...)* @__CxxFrameHandler3 to i8*) {
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entry:
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%cmp = icmp eq i16 %a, 10
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br i1 %cmp, label %if.then, label %if.else
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if.then:
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%call1 = invoke i16 @f()
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to label %cleanup unwind label %catch.dispatch
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if.else:
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%call2 = invoke i16 @f()
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to label %cleanup unwind label %catch.dispatch
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catch.dispatch:
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%cs = catchswitch within none [ label %catch, label %catch.2, label %catch.3 ] unwind to caller
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catch:
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catchpad within %cs [i8* null, i32 8, i8* null]
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call void @throw() noreturn
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br label %unreachable
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catch.2:
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%c2 = catchpad within %cs [i8* null, i32 32, i8* null]
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store i8 1, i8* %b
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catchret from %c2 to label %cleanup
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catch.3:
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%c3 = catchpad within %cs [i8* null, i32 64, i8* null]
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store i8 2, i8* %b
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catchret from %c3 to label %cleanup
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cleanup:
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%retval = phi i16 [ %call1, %if.then ], [ %call2, %if.else ], [ -1, %catch.2 ], [ -1, %catch.3 ]
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ret i16 %retval
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unreachable:
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unreachable
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}
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; This test verifies the case where three funclet blocks all meet the old
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; criteria to be placed at the end. The order of the blocks is not important
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; for the purposes of this test. The failure mode is an infinite loop during
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; compilation.
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;
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; CHECK-LABEL: .def test2;
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