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dag combine induces cycle when folding c ? (load p) : (load q) #1486

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asl opened this issue Jan 16, 2007 · 5 comments
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dag combine induces cycle when folding c ? (load p) : (load q) #1486

asl opened this issue Jan 16, 2007 · 5 comments
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@lattner
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bugzilla Issues migrated from bugzilla compile-fail Use [accepts-invalid] and [rejects-valid] instead llvm:codegen

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@asl
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asl commented Jan 16, 2007

Bugzilla Link 1114
Resolution FIXED
Resolved on Feb 22, 2010 12:53
Version 1.7
OS All
Attachments Failed bytecode

Extended Description

./llc bugpoint-reduced-simplified.bc
llc: /home/asl/proj/llvm/src/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp:336: void
::SelectionDAGLegalize::LegalizeDAG(): Assertion `Order.size() ==
Visited.size() && Order.size() == (unsigned)std::distance(DAG.allnodes_begin(),
DAG.allnodes_end()) && "Error: DAG is cyclic!"' failed.

This is reduction from Mozilla.
@asl
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asl commented Jan 16, 2007

assigned to @lattner

@lattner
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lattner commented Jan 16, 2007

looks like a dag combine issue.

@lattner
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lattner commented Jan 16, 2007

reduced testcase:

declare i1 %foo()

define i32 %test(i32* %A, i32* %B) {
%a = load i32* %A
%b = load i32* %B
%cond = call i1 %foo()
%c = select i1 %cond, i32 %a, i32 %b
ret i32 %c
}

@lattner
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lattner commented Jan 16, 2007

Fixed. Testcase here: CodeGen/Generic/2007-01-15-LoadSelectCycle.ll

Patch here:

-Chris

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lattner commented Jan 16, 2007

no really! patch here: http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-
Mon-20070115/042758.html

@llvmbot llvmbot transferred this issue from llvm/llvm-bugzilla-archive Dec 3, 2021
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bugzilla Issues migrated from bugzilla compile-fail Use [accepts-invalid] and [rejects-valid] instead llvm:codegen
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