From 18fdabadca110671b436de52fe7bd492ad49e656 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Fri, 5 Mar 2010 06:19:13 +0000 Subject: [PATCH] Fix PR6497, a bug where we'd fold a load into an addc node which has a flag. That flag in turn was used by an already-selected adde which turned into an ADC32ri8 which used a selected load which was chained to the load we folded. This flag use caused us to form a cycle. Fix this by not ignoring chains in IsLegalToFold even in cases where the isel thinks it can. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97791 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp | 7 +++++++ test/CodeGen/X86/crash.ll | 20 +++++++++++++++++++ 2 files changed, 27 insertions(+) create mode 100644 test/CodeGen/X86/crash.ll diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp index b9ec4c46f3b..f426fb1f3fa 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp @@ -1485,7 +1485,14 @@ bool SelectionDAGISel::IsLegalToFold(SDValue N, SDNode *U, SDNode *Root, break; Root = FU; VT = Root->getValueType(Root->getNumValues()-1); + + // If our query node has a flag result with a use, we've walked up it. If + // the user (which has already been selected) has a chain or indirectly uses + // the chain, our WalkChainUsers predicate will not consider it. Because of + // this, we cannot ignore chains in this predicate. + IgnoreChains = false; } + SmallPtrSet Visited; return !findNonImmUse(Root, N.getNode(), U, Root, Visited, IgnoreChains); diff --git a/test/CodeGen/X86/crash.ll b/test/CodeGen/X86/crash.ll new file mode 100644 index 00000000000..1e13046f2ac --- /dev/null +++ b/test/CodeGen/X86/crash.ll @@ -0,0 +1,20 @@ +; RUN: llc -march=x86 %s -o - +; RUN: llc -march=x86-64 %s -o - + +; PR6497 + +; Chain and flag folding issues. +define i32 @test1() nounwind ssp { +entry: + %tmp5.i = volatile load i32* undef ; [#uses=1] + %conv.i = zext i32 %tmp5.i to i64 ; [#uses=1] + %tmp12.i = volatile load i32* undef ; [#uses=1] + %conv13.i = zext i32 %tmp12.i to i64 ; [#uses=1] + %shl.i = shl i64 %conv13.i, 32 ; [#uses=1] + %or.i = or i64 %shl.i, %conv.i ; [#uses=1] + %add16.i = add i64 %or.i, 256 ; [#uses=1] + %shr.i = lshr i64 %add16.i, 8 ; [#uses=1] + %conv19.i = trunc i64 %shr.i to i32 ; [#uses=1] + volatile store i32 %conv19.i, i32* undef + ret i32 undef +}