[SelectionDAG] Fix UpdateChains handling of TokenFactors

Summary:
In Instruction Selection UpdateChains replaces all matched Nodes'
chain references including interior token factors and deletes them.
This may allow nodes which depend on these interior nodes but are not
part of the set of matched nodes to be left with a dangling dependence.
Avoid this by doing the replacement for matched non-TokenFactor nodes.

Fixes PR36164.

Reviewers: jonpa, RKSimon, bogner

Subscribers: llvm-commits, hiraditya

Differential Revision: https://reviews.llvm.org/D42754

llvm-svn: 323977

2 files changed, 115 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index b3a316b93b4..ab0a2293666 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -2365,7 +2365,8 @@ void SelectionDAGISel::UpdateChains(
             std::replace(ChainNodesMatched.begin(), ChainNodesMatched.end(), N,
                          static_cast<SDNode *>(nullptr));
           });
-      CurDAG->ReplaceAllUsesOfValueWith(ChainVal, InputChain);
+      if (ChainNode->getOpcode() != ISD::TokenFactor)
+        CurDAG->ReplaceAllUsesOfValueWith(ChainVal, InputChain);
 
       // If the node became dead and we haven't already seen it, delete it.
       if (ChainNode != NodeToMatch && ChainNode->use_empty() &&
diff --git a/llvm/test/CodeGen/SystemZ/pr36164.ll b/llvm/test/CodeGen/SystemZ/pr36164.ll
new file mode 100644
index 00000000000..0c850091d31
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/pr36164.ll
@@ -0,0 +1,113 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc %s -o - -mtriple=s390x-linux-gnu -mcpu=z13 -disable-basicaa | FileCheck %s
+
+; This test checks that we do not a reference to a deleted node.
+
+%0 = type { i32 }
+
+@g_11 = external dso_local unnamed_addr global i1, align 4
+@g_69 = external dso_local global i32, align 4
+@g_73 = external dso_local unnamed_addr global i32, align 4
+@g_832 = external dso_local constant %0, align 4
+@g_938 = external dso_local unnamed_addr global i64, align 8
+
+; Function Attrs: nounwind
+define void @main() local_unnamed_addr #0 {
+; CHECK-LABEL: main:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    stmg %r12, %r15, 96(%r15)
+; CHECK-NEXT:    .cfi_offset %r12, -64
+; CHECK-NEXT:    .cfi_offset %r13, -56
+; CHECK-NEXT:    .cfi_offset %r14, -48
+; CHECK-NEXT:    .cfi_offset %r15, -40
+; CHECK-NEXT:    lhi %r0, 1
+; CHECK-NEXT:    larl %r1, g_938
+; CHECK-NEXT:    lhi %r2, 2
+; CHECK-NEXT:    lhi %r3, 3
+; CHECK-NEXT:    lhi %r4, 0
+; CHECK-NEXT:    lhi %r5, 4
+; CHECK-NEXT:    larl %r14, g_11
+; CHECK-NEXT:  .LBB0_1: # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT:    strl %r0, g_73
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    strl %r0, g_69
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    lghi %r13, 24
+; CHECK-NEXT:    strl %r2, g_69
+; CHECK-NEXT:    ag %r13, 0(%r1)
+; CHECK-NEXT:    lrl %r12, g_832
+; CHECK-NEXT:    strl %r3, g_69
+; CHECK-NEXT:    lrl %r12, g_832
+; CHECK-NEXT:    strl %r4, g_69
+; CHECK-NEXT:    lrl %r12, g_832
+; CHECK-NEXT:    strl %r0, g_69
+; CHECK-NEXT:    lrl %r12, g_832
+; CHECK-NEXT:    strl %r2, g_69
+; CHECK-NEXT:    lrl %r12, g_832
+; CHECK-NEXT:    strl %r3, g_69
+; CHECK-NEXT:    stgrl %r13, g_938
+; CHECK-NEXT:    lrl %r13, g_832
+; CHECK-NEXT:    strl %r5, g_69
+; CHECK-NEXT:    mvi 0(%r14), 1
+; CHECK-NEXT:    j .LBB0_1
+  br label %1
+
+; <label>:1:                                      ; preds = %1, %0
+  store i32 1, i32* @g_73, align 4
+  %2 = load i64, i64* @g_938, align 8
+  store i32 0, i32* @g_69, align 4
+  %3 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  %4 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  %5 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  %6 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 1, i32* @g_69, align 4
+  %7 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  %8 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 3, i32* @g_69, align 4
+  %9 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  %10 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 1, i32* @g_69, align 4
+  %11 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 2, i32* @g_69, align 4
+  %12 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 3, i32* @g_69, align 4
+  %13 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 0, i32* @g_69, align 4
+  %14 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  %15 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  %16 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  %17 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 1, i32* @g_69, align 4
+  %18 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 2, i32* @g_69, align 4
+  %19 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 3, i32* @g_69, align 4
+  %20 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 0, i32* @g_69, align 4
+  %21 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 1, i32* @g_69, align 4
+  %22 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 2, i32* @g_69, align 4
+  %23 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 3, i32* @g_69, align 4
+  %24 = add i64 %2, 24
+  store i64 %24, i64* @g_938, align 8
+  %25 = load volatile i32, i32* getelementptr inbounds (%0, %0* @g_832, i64 0, i32 0), align 4
+  store i32 4, i32* @g_69, align 4
+  store i1 true, i1* @g_11, align 4
+  br label %1
+}