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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
108 lines
4.1 KiB
LLVM
108 lines
4.1 KiB
LLVM
; RUN: llc < %s | FileCheck %s
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; Started from this code:
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; void f() {
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; try {
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; try {
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; throw 42;
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; } catch (int) {
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; }
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; try {
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; throw 42;
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; } catch (int) {
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; }
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; } catch (int) {
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; }
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; }
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; Don't tail merge the calls.
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; CHECK: calll __CxxThrowException@8
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; CHECK: calll __CxxThrowException@8
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; ModuleID = 'cppeh-pingpong.cpp'
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target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
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target triple = "i686-pc-windows-msvc"
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%rtti.TypeDescriptor2 = type { i8**, i8*, [3 x i8] }
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%eh.CatchableType = type { i32, i8*, i32, i32, i32, i32, i8* }
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%eh.CatchableTypeArray.1 = type { i32, [1 x %eh.CatchableType*] }
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%eh.ThrowInfo = type { i32, i8*, i8*, i8* }
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$"\01??_R0H@8" = comdat any
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$"_CT??_R0H@84" = comdat any
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$_CTA1H = comdat any
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$_TI1H = comdat any
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@"\01??_7type_info@@6B@" = external constant i8*
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@"\01??_R0H@8" = linkonce_odr global %rtti.TypeDescriptor2 { i8** @"\01??_7type_info@@6B@", i8* null, [3 x i8] c".H\00" }, comdat
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@"_CT??_R0H@84" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 1, i8* bitcast (%rtti.TypeDescriptor2* @"\01??_R0H@8" to i8*), i32 0, i32 -1, i32 0, i32 4, i8* null }, section ".xdata", comdat
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@_CTA1H = linkonce_odr unnamed_addr constant %eh.CatchableTypeArray.1 { i32 1, [1 x %eh.CatchableType*] [%eh.CatchableType* @"_CT??_R0H@84"] }, section ".xdata", comdat
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@_TI1H = linkonce_odr unnamed_addr constant %eh.ThrowInfo { i32 0, i8* null, i8* null, i8* bitcast (%eh.CatchableTypeArray.1* @_CTA1H to i8*) }, section ".xdata", comdat
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define void @"\01?f@@YAXXZ"() #0 personality i8* bitcast (i32 (...)* @__CxxFrameHandler3 to i8*) {
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entry:
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%i = alloca i32, align 4
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%tmp = alloca i32, align 4
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%tmp1 = alloca i32, align 4
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store i32 0, i32* %i, align 4
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store i32 42, i32* %tmp, align 4
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%0 = bitcast i32* %tmp to i8*
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invoke void @_CxxThrowException(i8* %0, %eh.ThrowInfo* @_TI1H) #1
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to label %unreachable unwind label %catch.dispatch
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catch.dispatch: ; preds = %entry
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%cs1 = catchswitch within none [label %catch] unwind label %catch.dispatch.7
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catch: ; preds = %catch.dispatch
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%1 = catchpad within %cs1 [%rtti.TypeDescriptor2* @"\01??_R0H@8", i32 0, i8* null]
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catchret from %1 to label %catchret.dest
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catchret.dest: ; preds = %catch
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br label %try.cont
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try.cont: ; preds = %catchret.dest
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store i32 42, i32* %tmp1, align 4
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%2 = bitcast i32* %tmp1 to i8*
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invoke void @_CxxThrowException(i8* %2, %eh.ThrowInfo* @_TI1H) #1
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to label %unreachable unwind label %catch.dispatch.2
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catch.dispatch.2: ; preds = %try.cont
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%cs2 = catchswitch within none [label %catch.4] unwind label %catch.dispatch.7
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catch.4: ; preds = %catch.dispatch.2
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%3 = catchpad within %cs2 [%rtti.TypeDescriptor2* @"\01??_R0H@8", i32 0, i8* null]
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catchret from %3 to label %catchret.dest.5
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catchret.dest.5: ; preds = %catch.4
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br label %try.cont.6
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try.cont.6: ; preds = %catchret.dest.5
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br label %try.cont.11
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catch.dispatch.7:
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%cs3 = catchswitch within none [label %catch.9] unwind to caller
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catch.9: ; preds = %catch.dispatch.7
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%4 = catchpad within %cs3 [%rtti.TypeDescriptor2* @"\01??_R0H@8", i32 0, i8* null]
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catchret from %4 to label %catchret.dest.10
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catchret.dest.10: ; preds = %catch.9
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br label %try.cont.11
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try.cont.11: ; preds = %catchret.dest.10, %try.cont.6
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ret void
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unreachable: ; preds = %try.cont, %entry
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unreachable
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}
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declare x86_stdcallcc void @_CxxThrowException(i8*, %eh.ThrowInfo*)
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declare i32 @__CxxFrameHandler3(...)
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attributes #0 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #1 = { noreturn }
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