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Inlining functions with block addresses can cause many problem and requires a rich infrastructure to support including escape analysis. At this point the safest approach to address these problems is by blocking inlining from happening. Background: There have been reports on Ruby segmentation faults triggered by inlining functions with block addresses like //Ruby code snippet vm_exec_core() { finish_insn_seq_0 = &&INSN_LABEL_finish; INSN_LABEL_finish: ; } This kind of scenario can also happen when LLVM picks a subset of blocks for inlining, which is the case with the actual code in the Ruby environment. LLVM suppresses inlining for such functions when there is an indirect branch. The attached patch does so even when there is no indirect branch. Note that user code like above would not make much sense: using the global for jumping across function boundaries would be illegal. Why was there a segfault: In the snipped above the block with the label is recognized as dead So it is eliminated. Instead of a block address the cloner stores a constant (sic!) into the global resulting in the segfault (when the global is used in a goto). Why had it worked in the past then: By luck. In older versions vm_exec_core was also inlined but the label address used was the block label address in vm_exec_core. So the global jump ended up in the original function rather than in the caller which accidentally happened to work. Test case ./tools/clang/test/CodeGen/indirect-goto.c will fail as a result of this commit. rdar://17245966 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212077 91177308-0d34-0410-b5e6-96231b3b80d8
29 lines
646 B
LLVM
29 lines
646 B
LLVM
; RUN: opt -inline -S < %s | FileCheck %s
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; PR10162
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; Make sure doit is not inlined since the blockaddress is taken
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; which could be unsafe
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; CHECK: store i8* blockaddress(@doit, %here), i8** %pptr, align 8
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@i = global i32 1, align 4
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@ptr1 = common global i8* null, align 8
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define void @doit(i8** nocapture %pptr, i32 %cond) nounwind uwtable {
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entry:
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%tobool = icmp eq i32 %cond, 0
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br i1 %tobool, label %if.end, label %here
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here:
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store i8* blockaddress(@doit, %here), i8** %pptr, align 8
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br label %if.end
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if.end:
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ret void
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}
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define void @f(i32 %cond) nounwind uwtable {
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entry:
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call void @doit(i8** @ptr1, i32 %cond)
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ret void
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}
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