From 5ba8bf6d28ad350114a4b02f01d70ebe08612cfe Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Fri, 5 Feb 2010 01:27:11 +0000
Subject: [PATCH] When the scheduler unfold a load folding instruction it move
 some of the predecessors to the unfolded load. It decides what gets moved to
 the load by checking whether the new load is using the predecessor as an
 operand. The check neglects the cases whether the predecessor is a flagged
 scheduling unit. rdar://7604000

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95339 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../SelectionDAG/ScheduleDAGRRList.cpp        | 12 ++++++--
 test/CodeGen/X86/2010-02-04-SchedulerBug.ll   | 28 +++++++++++++++++++
 2 files changed, 38 insertions(+), 2 deletions(-)
 create mode 100644 test/CodeGen/X86/2010-02-04-SchedulerBug.ll

diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
index dea59937198..72a07dcb04c 100644
--- a/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
@@ -345,6 +345,15 @@ void ScheduleDAGRRList::BacktrackBottomUp(SUnit *SU, unsigned BtCycle,
   ++NumBacktracks;
 }
 
+static bool isOperandOf(const SUnit *SU, SDNode *N) {
+  for (const SDNode *SUNode = SU->getNode(); SUNode;
+       SUNode = SUNode->getFlaggedNode()) {
+    if (SUNode->isOperandOf(N))
+      return true;
+  }
+  return false;
+}
+
 /// CopyAndMoveSuccessors - Clone the specified node and move its scheduled
 /// successors to the newly created node.
 SUnit *ScheduleDAGRRList::CopyAndMoveSuccessors(SUnit *SU) {
@@ -427,8 +436,7 @@ SUnit *ScheduleDAGRRList::CopyAndMoveSuccessors(SUnit *SU) {
          I != E; ++I) {
       if (I->isCtrl())
         ChainPreds.push_back(*I);
-      else if (I->getSUnit()->getNode() &&
-               I->getSUnit()->getNode()->isOperandOf(LoadNode))
+      else if (isOperandOf(I->getSUnit(), LoadNode))
         LoadPreds.push_back(*I);
       else
         NodePreds.push_back(*I);
diff --git a/test/CodeGen/X86/2010-02-04-SchedulerBug.ll b/test/CodeGen/X86/2010-02-04-SchedulerBug.ll
new file mode 100644
index 00000000000..c966e21d52d
--- /dev/null
+++ b/test/CodeGen/X86/2010-02-04-SchedulerBug.ll
@@ -0,0 +1,28 @@
+; RUN: llc < %s -mtriple=i386-apple-darwin11
+; rdar://7604000
+
+%struct.a_t = type { i8*, i64*, i8*, i32, i32, i64*, i64*, i64* }
+%struct.b_t = type { i32, i32, i32, i32, i64, i64, i64, i64 }
+
+define void @t(i32 %cNum, i64 %max) nounwind optsize ssp noimplicitfloat {
+entry:
+  %0 = load %struct.b_t** null, align 4 ; <%struct.b_t*> [#uses=1]
+  %1 = getelementptr inbounds %struct.b_t* %0, i32 %cNum, i32 5 ; <i64*> [#uses=1]
+  %2 = load i64* %1, align 4                      ; <i64> [#uses=1]
+  %3 = icmp ult i64 %2, %max            ; <i1> [#uses=1]
+  %4 = getelementptr inbounds %struct.a_t* null, i32 0, i32 7 ; <i64**> [#uses=1]
+  %5 = load i64** %4, align 4                     ; <i64*> [#uses=0]
+  %6 = load i64* null, align 4                    ; <i64> [#uses=1]
+  br i1 %3, label %bb2, label %bb
+
+bb:                                               ; preds = %entry
+  br label %bb3
+
+bb2:                                              ; preds = %entry
+  %7 = or i64 %6, undef                           ; <i64> [#uses=1]
+  br label %bb3
+
+bb3:                                              ; preds = %bb2, %bb
+  %misc_enables.0 = phi i64 [ undef, %bb ], [ %7, %bb2 ] ; <i64> [#uses=0]
+  ret void
+}
-- 
2.34.1