您好，我最近升级到llvm 4.0，现在我从优化器中得到了最奇怪的错误，这似乎是最好的代码。我已经确定了下面似乎给出了错误的代码，并且打印出llvm给我的关于<badref>的断言，但是在它所讨论的代码中没有<badref>。这使我认为它可能是编译器错误或生成的代码不正确。
; ModuleID = '__form__module.$static.196'
source_filename = "__form__module.$static.196"
target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
%struct.clousure_type = type { void ()*, %struct.closure_vtable*, i8* }
%struct.closure_vtable = type { %struct.type_info*, void (i8*, i8*)*, void (i8*)*, i8 (i8*, i8*)*, i64 (i8*, i8*)* }
%struct.type_info = type { i8*, i8*, i64, i8, i8, i8, i8, %struct.type_info**, %struct.member_info* }
%struct.member_info = type { i8, %struct.type_info* }
@"$static.159$stub_ptr" = external hidden externally_initialized global void (%struct.clousure_type*, %struct.clousure_type*)*
define hidden void @"$static.196"(%struct.clousure_type*, %struct.clousure_type*, %struct.clousure_type*, i8) {
entry:
%4 = icmp eq i8 %3, 0
br i1 %4, label %bb2, label %bb4
bb2: ; preds = %entry
%5 = icmp eq %struct.clousure_type* %0, %2
br i1 %5, label %bb3, label %bb6
bb3: ; preds = %bb4, %bb2
ret void
bb4: ; preds = %entry
%6 = icmp eq %struct.clousure_type* %1, %2
br i1 %6, label %bb3, label %bb6
bb6: ; preds = %bb4, %bb2
tail call void @"$static.159"(%struct.clousure_type* %0, %struct.clousure_type* %1)
ret void
}
; Function Attrs: alwaysinline
define available_externally hidden void @"$static.159"(%struct.clousure_type*, %struct.clousure_type*) #0 {
entry:
%2 = load void (%struct.clousure_type*, %struct.clousure_type*)*, void (%struct.clousure_type*, %struct.clousure_type*)** @"$static.159$stub_ptr", align 8
tail call void %2(%struct.clousure_type* %0, %struct.clousure_type* %1)
ret void
}
attributes #0 = { alwaysinline }
While deleting: void (%struct.clousure_type*, %struct.clousure_type*)* %$static.159
Use still stuck around after Def is destroyed: call void @"$static.159"(%struct.clousure_type* <badref>, %struct.clousure_type* %0)
This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.
Assertion failed!
Program: C:\Users\RICH\workspace\formvm\Debug\formvm.exe
File: C:\llvm-4.0.0.src\lib\IR\Value.cpp, Line 85
Expression: use_empty() && "Uses remain when a value is destroyed!"
优化器正在处理的llvm ir代码，代表上面两个函数，是以下两个函数（从c ++生成）。
define private void @gen__fun__return_copy85(%struct.clousure_type*, %struct.clousure_type*, %struct.clousure_type*, i8) {
entry:
%4 = alloca %struct.clousure_type*, align 8
store %struct.clousure_type* %0, %struct.clousure_type** %4, align 8
%5 = load %struct.clousure_type*, %struct.clousure_type** %4, align 8
%6 = alloca %struct.clousure_type*, align 8
store %struct.clousure_type* %1, %struct.clousure_type** %6, align 8
%7 = load %struct.clousure_type*, %struct.clousure_type** %6, align 8
%8 = alloca %struct.clousure_type*, align 8
store %struct.clousure_type* %2, %struct.clousure_type** %8, align 8
%9 = load %struct.clousure_type*, %struct.clousure_type** %8, align 8
%10 = alloca i8, align 8
store i8 %3, i8* %10, align 8
%11 = load i8, i8* %10, align 8
%12 = icmp eq i8 %11, 0
br i1 %12, label %bb2, label %bb4
bb2: ; preds = %entry
%13 = icmp eq %struct.clousure_type* %5, %9
br i1 %13, label %bb3, label %bb6
bb3: ; preds = %bb2
ret void
bb4: ; preds = %entry
%14 = icmp eq %struct.clousure_type* %7, %9
br i1 %14, label %bb5, label %bb6
bb5: ; preds = %bb4
ret void
bb6: ; preds = %bb4, %bb2
call void @_ZN13clousure_typeC2ERKS_(%struct.clousure_type* %5, %struct.clousure_type* %7)
ret void
}
define private void @_ZN13clousure_typeC2ERKS_(%struct.clousure_type* %this, %struct.clousure_type* %rhs) {
%1 = alloca %struct.clousure_type*, align 8
%2 = alloca %struct.clousure_type*, align 8
store %struct.clousure_type* %this, %struct.clousure_type** %1, align 8
store %struct.clousure_type* %rhs, %struct.clousure_type** %2, align 8
%3 = load %struct.clousure_type*, %struct.clousure_type** %1, align 8
%4 = getelementptr %struct.clousure_type, %struct.clousure_type* %3, i32 0, i32 0
store void ()* null, void ()** %4, align 8
%5 = getelementptr %struct.clousure_type, %struct.clousure_type* %3, i32 0, i32 1
store %struct.closure_vtable* null, %struct.closure_vtable** %5, align 8
%6 = getelementptr %struct.clousure_type, %struct.clousure_type* %3, i32 0, i32 2
store i8* null, i8** %6, align 8
%7 = load %struct.clousure_type*, %struct.clousure_type** %2, align 8
call void @_ZN13clousure_type4copyERKS_(%struct.clousure_type* %3, %struct.clousure_type* %7)
ret void
}
要添加以下传递，我是否需要更改任何添加，哪些可能导致问题？
FPM->add(llvm::createCFGSimplificationPass());
FPM->add(llvm::createInstructionCombiningPass());
FPM->add(llvm::createPromoteMemoryToRegisterPass());
FPM->add(llvm::createCFGSimplificationPass());
FPM->add(llvm::createLICMPass());
FPM->add(llvm::createLoopDeletionPass());
FPM->add(llvm::createLoopUnrollPass());
FPM->add(llvm::createSCCPPass());
FPM->add(llvm::createCFGSimplificationPass());
FPM->add(llvm::createInstructionCombiningPass());
FPM->add(llvm::createDeadStoreEliminationPass());
FPM->add(llvm::createAggressiveDCEPass());
FPM->add(llvm::createCFGSimplificationPass());
FPM->add(llvm::createTailCallEliminationPass());
编辑即使我删除了所有的传递，我仍然会收到错误！
目前似乎问题源于以下函数@"$static.159"，而不是函数尝试load @"$static.159$stub_ptr"。理论是它无法在尝试加载自身时将其删除？
; Function Attrs: alwaysinline
define available_externally hidden void @"$static.159"(%struct.clousure_type*, %struct.clousure_type*) #0 {
entry:
%2 = load void (%struct.clousure_type*, %struct.clousure_type*)*, void (%struct.clousure_type*, %struct.clousure_type*)** @"$static.159$stub_ptr"
tail call void %2(%struct.clousure_type* %0, %struct.clousure_type* %1)
ret void
}
答案 0 :(得分：0)
升级到llvm 5.0以最终处理此错误。
这不是理论上的问题。简单地放入我在函数指针中存储的函数之一，由于生成上述代码的c ++代码中的错误初始化指针导致上面找到的<badref>，因此没有生成alloca。请注意，<badref>仅在稍后由于使用函数指针而被优化器找到!!
为什么这个指针不会导致早期的段错误我不知道，但它没有，允许不正确的代码生成。在llvm 5.0上，指针按预期给出了段错误，允许我找到错误。