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https://github.com/RPCS3/llvm.git
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Peter Collingbourne
02296e214b
This intrinsic safely loads a function pointer from a virtual table pointer using type metadata. This intrinsic is used to implement control flow integrity in conjunction with virtual call optimization. The virtual call optimization pass will optimize away llvm.type.checked.load intrinsics associated with devirtualized calls, thereby removing the type check in cases where it is not needed to enforce the control flow integrity constraint. This patch also introduces the capability to copy type metadata between global variables, and teaches the virtual call optimization pass to do so. Differential Revision: http://reviews.llvm.org/D21121 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273756 91177308-0d34-0410-b5e6-96231b3b80d8
39 lines
1.0 KiB
LLVM
39 lines
1.0 KiB
LLVM
; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
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target datalayout = "e-p:64:64"
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target triple = "x86_64-unknown-linux-gnu"
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@vt1 = constant [1 x i8*] [i8* bitcast (void (i8*)* @vf to i8*)], !type !0
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@vt2 = constant [1 x i8*] [i8* bitcast (void (i8*)* @vf to i8*)], !type !0
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define void @vf(i8* %this) {
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ret void
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}
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; CHECK: define void @call
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define void @call(i8* %obj) {
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%vtableptr = bitcast i8* %obj to [1 x i8*]**
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%vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
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%vtablei8 = bitcast [1 x i8*]* %vtable to i8*
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%pair = call {i8*, i1} @llvm.type.checked.load(i8* %vtablei8, i32 0, metadata !"typeid")
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%fptr = extractvalue {i8*, i1} %pair, 0
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%p = extractvalue {i8*, i1} %pair, 1
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; CHECK: br i1 true,
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br i1 %p, label %cont, label %trap
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cont:
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%fptr_casted = bitcast i8* %fptr to void (i8*)*
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; CHECK: call void @vf(
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call void %fptr_casted(i8* %obj)
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ret void
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trap:
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call void @llvm.trap()
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unreachable
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}
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declare {i8*, i1} @llvm.type.checked.load(i8*, i32, metadata)
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declare void @llvm.trap()
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!0 = !{i32 0, !"typeid"}
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