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373af89ec1
We're getting bug reports: https://bugs.llvm.org/show_bug.cgi?id=35807 https://bugs.llvm.org/show_bug.cgi?id=35840 https://bugs.llvm.org/show_bug.cgi?id=36045 ...where we blow up the stack in value tracking because other passes are sending in selects that have an operand that is itself the select. We don't currently have a reliable way to avoid analyzing dead code that may take non-standard forms, so bail out when things go too far. This mimics the recursion depth limitations in other parts of value tracking. Unfortunately, this pushes the underlying problems for other passes (jump-threading, simplifycfg, correlated-propagation) into hiding. If someone wants to uncover those again, the first draft of this patch on Phab would do that (it would assert rather than bail out). Differential Revision: https://reviews.llvm.org/D42442 llvm-svn: 323331
47 lines
865 B
LLVM
47 lines
865 B
LLVM
; RUN: opt -simplifycfg < %s -S | FileCheck %s
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; The dead code would cause a select that had itself
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; as an operand to be analyzed. This would then cause
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; infinite recursion and eventual crash.
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define void @PR36045(i1 %t, i32* %b) {
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; CHECK-LABEL: @PR36045(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: ret void
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;
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entry:
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br i1 %t, label %if, label %end
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if:
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br i1 %t, label %unreach, label %pre
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unreach:
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unreachable
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pre:
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%p = phi i32 [ 70, %if ], [ %sel, %for ]
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br label %for
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for:
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%cmp = icmp sgt i32 %p, 8
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%add = add i32 %p, 2
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%sel = select i1 %cmp, i32 %p, i32 %add
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%cmp21 = icmp ult i32 %sel, 21
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br i1 %cmp21, label %pre, label %for.end
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for.end:
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br i1 %t, label %unreach2, label %then12
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then12:
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store i32 0, i32* %b
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br label %unreach2
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unreach2:
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%spec = phi i32 [ %sel, %for.end ], [ 42, %then12 ]
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unreachable
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end:
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ret void
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}
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