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c7d7e0cbe0
when it detects undefined behavior. llvm.trap generally codegens into some
thing really small (e.g. a 2 byte ud2 instruction on x86) and debugging this
sort of thing is "nontrivial". For example, we now compile:
void foo() { *(int*)0 = 42; }
into:
_foo:
pushl %ebp
movl %esp, %ebp
ud2
Some may even claim that this is a security hole, though that seems dubious
to me. This addresses rdar://7958343 - Optimizing away null dereference
potentially allows arbitrary code execution
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103356 91177308-0d34-0410-b5e6-96231b3b80d8
34 lines
726 B
LLVM
34 lines
726 B
LLVM
; RUN: opt < %s -simplifycfg -S | FileCheck %s
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; PR2967
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target datalayout =
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"e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32"
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target triple = "i386-pc-linux-gnu"
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define void @test1(i32 %x) nounwind {
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entry:
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%0 = icmp eq i32 %x, 0 ; <i1> [#uses=1]
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br i1 %0, label %bb, label %return
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bb: ; preds = %entry
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%1 = volatile load i32* null
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unreachable
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br label %return
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return: ; preds = %entry
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ret void
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; CHECK: @test1
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; CHECK: volatile load
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}
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; rdar://7958343
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define void @test2() nounwind {
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entry:
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store i32 4,i32* null
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ret void
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; CHECK: @test2
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; CHECK: call void @llvm.trap
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; CHECK: unreachable
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}
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