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Fix for PR#30562: Selection DAG error: Detected cycle in SelectionDAG. 

Patch by Dinar Temirbulatov

llvm-svn: 300314
This commit is contained in:
Andrew V. Tischenko 2017-04-14 09:17:09 +00:00
parent 1a1678e7eb
commit 4e7bcd5216
2 changed files with 27 additions and 2 deletions
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7
llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
View File

@ -1192,8 +1192,11 @@ SDValue SelectionDAGLegalize::ExpandExtractFromVectorThroughStack(SDValue Op) {
// If the index is dependent on the store we will introduce a cycle when
// creating the load (the load uses the index, and by replacing the chain
// we will make the index dependent on the load).
if (SDNode::hasPredecessorHelper(ST, Visited, Worklist))
// we will make the index dependent on the load). Also, the store might be
// dependent on the extractelement and introduce a cycle when creating
// the load.
if (SDNode::hasPredecessorHelper(ST, Visited, Worklist) ||
ST->hasPredecessor(Op.getNode()))
continue;
StackPtr = ST->getBasePtr();

22
llvm/test/CodeGen/X86/pr30562.ll Normal file
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@ -0,0 +1,22 @@
; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s
define i32 @foo(i64* nocapture %perm, i32 %n) {
entry:
br label %body
body:
; CHECK-LABEL: foo:
; CHECK: pslldq $8, %xmm0
%vec.ind = phi <2 x i64> [ <i64 0, i64 1>, %entry ], [ <i64 2, i64 3>, %body ]
%l13 = extractelement <2 x i64> %vec.ind, i32 %n
%l14 = getelementptr inbounds i64, i64* %perm, i64 %l13
%l15 = bitcast i64* %l14 to <2 x i64>*
store <2 x i64> %vec.ind, <2 x i64>* %l15, align 8
%niter.ncmp.3 = icmp eq i64 %l13, 0
br i1 %niter.ncmp.3, label %exit, label %body
exit:
ret i32 %n
}