[MachinePipeliner] Don't check boundary node in checkValidNodeOrder

[jsji]

Summary

This was exposed by PowerPC target enablement - caught by Asan build.

In ScheduleDAG, if we haven't seen any uses in this scheduling region,
we will create a dependence edge to ExitSU to model the live-out latency.
This is required for vreg defs with no in-region use, and prefetches with
no vreg def.

eg:

SU(6):   %4:g8rc = COPY %17:g8rc_and_g8rc_nox0
  # preds left       : 2
  # succs left       : 1
  # rdefs left       : 0
  Latency            : 2
  Depth              : 10
  Height             : 1
  Predecessors:
    SU(5): Data Latency=1 Reg=%17
    SU(2): Anti Latency=1
  Successors:
    ExitSU: Ord  Latency=1 Artificial

When we build NodeOrder in Scheduler, we ignore these boundary nodes.
However, when we check Succs in checkValidNodeOrder, we did not skip
them, but we still assume all the nodes have been sorted and in order in
Indices array, so we lower_bound() will return Indices.end(), causing
memory issues.

[hfinkel]

LGTM

llvm/lib/CodeGen/MachinePipeliner.cpp

3736 ↗

(On Diff #204555)

space after , before std.

[jsji]

Thanks. Will update the comments in commit.

llvm/trunk/lib/CodeGen/MachinePipeliner.cpp

for (SDep &PredEdge : SU->Preds) {
         PredBefore = true;
         Pred = PredSU;
         break;
       }
     }
 
     for (SDep &SuccEdge : SU->Succs) {
       SUnit *SuccSU = SuccEdge.getSUnit();
+      // Do not process a boundary node, it was not included in NodeOrder,
+      // hence not in Indices either, call to std::lower_bound() below will
+      // return Indices.end().
+      if (SuccSU->isBoundaryNode())
+        continue;
       unsigned SuccIndex =
           std::get<1>(*std::lower_bound(Indices.begin(), Indices.end(),
                                         std::make_pair(SuccSU, 0), CompareKey));
       if (!SuccSU->getInstr()->isPHI() && SuccIndex < Index) {
         SuccBefore = true;
         Succ = SuccSU;
         break;
       }

llvm/trunk/test/CodeGen/PowerPC/sms-simple.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -ppc-vsr-nums-as-vr -mtriple=powerpc64-unknown-linux-gnu \
+; RUN:       -verify-machineinstrs -ppc-asm-full-reg-names -mcpu=pwr9 --ppc-enable-pipeliner \
+; RUN:       | FileCheck %s
+
+@x = dso_local local_unnamed_addr global <{ i32, i32, i32, i32, [1020 x i32] }> <{ i32 1, i32 2, i32 3, i32 4, [1020 x i32] zeroinitializer }>, align 4
+@y = common dso_local global [1024 x i32] zeroinitializer, align 4
+
+; Function Attrs: norecurse nounwind
+define dso_local i32* @foo() local_unnamed_addr #0 {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    addis r5, r2, x@toc@ha
+; CHECK-NEXT:    addi r5, r5, x@toc@l
+; CHECK-NEXT:    addis r6, r2, y@toc@ha
+; CHECK-NEXT:    li r7, 340
+; CHECK-NEXT:    addi r3, r6, y@toc@l
+; CHECK-NEXT:    lwz r6, y@toc@l(r6)
+; CHECK-NEXT:    mtctr r7
+; CHECK-NEXT:    addi r5, r5, -8
+; CHECK-NEXT:    lwzu r7, 12(r5)
+; CHECK-NEXT:    maddld r6, r7, r7, r6
+; CHECK-NEXT:    lwz r7, 4(r5)
+; CHECK-NEXT:    addi r4, r3, -8
+; CHECK-NEXT:    stwu r6, 12(r4)
+; CHECK-NEXT:    maddld r6, r7, r7, r6
+; CHECK-NEXT:    lwz r7, 8(r5)
+; CHECK-NEXT:    .p2align 4
+; CHECK-NEXT:  .LBB0_1: # %for.body
+; CHECK:         maddld r7, r7, r7, r6
+; CHECK-NEXT:    lwzu r8, 12(r5)
+; CHECK-NEXT:    maddld r8, r8, r8, r7
+; CHECK-NEXT:    stw r6, 4(r4)
+; CHECK-NEXT:    lwz r6, 4(r5)
+; CHECK-NEXT:    maddld r6, r6, r6, r8
+; CHECK-NEXT:    stw r7, 8(r4)
+; CHECK-NEXT:    lwz r7, 8(r5)
+; CHECK-NEXT:    stwu r8, 12(r4)
+; CHECK-NEXT:    bdnz .LBB0_1
+; CHECK-NEXT:  # %bb.2:
+; CHECK-NEXT:    maddld r5, r7, r7, r6
+; CHECK-NEXT:    stw r6, 4(r4)
+; CHECK-NEXT:    stw r5, 8(r4)
+; CHECK-NEXT:    blr
+entry:
+  %.pre = load i32, i32* getelementptr inbounds ([1024 x i32], [1024 x i32]* @y, i64 0, i64 0), align 4
+  br label %for.body
+
+for.cond.cleanup:                                 ; preds = %for.body
+  ret i32* getelementptr inbounds ([1024 x i32], [1024 x i32]* @y, i64 0, i64 0)
+
+for.body:                                         ; preds = %for.body, %entry
+  %0 = phi i32 [ %.pre, %entry ], [ %add.2, %for.body ]
+  %indvars.iv = phi i64 [ 1, %entry ], [ %indvars.iv.next.2, %for.body ]
+  %arrayidx2 = getelementptr inbounds [1024 x i32], [1024 x i32]* bitcast (<{ i32, i32, i32, i32, [1020 x i32] }>* @x to [1024 x i32]*), i64 0, i64 %indvars.iv
+  %1 = load i32, i32* %arrayidx2, align 4
+  %mul = mul nsw i32 %1, %1
+  %add = add nsw i32 %mul, %0
+  %arrayidx6 = getelementptr inbounds [1024 x i32], [1024 x i32]* @y, i64 0, i64 %indvars.iv
+  store i32 %add, i32* %arrayidx6, align 4
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %arrayidx2.1 = getelementptr inbounds [1024 x i32], [1024 x i32]* bitcast (<{ i32, i32, i32, i32, [1020 x i32] }>* @x to [1024 x i32]*), i64 0, i64 %indvars.iv.next
+  %2 = load i32, i32* %arrayidx2.1, align 4
+  %mul.1 = mul nsw i32 %2, %2
+  %add.1 = add nsw i32 %mul.1, %add
+  %arrayidx6.1 = getelementptr inbounds [1024 x i32], [1024 x i32]* @y, i64 0, i64 %indvars.iv.next
+  store i32 %add.1, i32* %arrayidx6.1, align 4
+  %indvars.iv.next.1 = add nuw nsw i64 %indvars.iv, 2
+  %arrayidx2.2 = getelementptr inbounds [1024 x i32], [1024 x i32]* bitcast (<{ i32, i32, i32, i32, [1020 x i32] }>* @x to [1024 x i32]*), i64 0, i64 %indvars.iv.next.1
+  %3 = load i32, i32* %arrayidx2.2, align 4
+  %mul.2 = mul nsw i32 %3, %3
+  %add.2 = add nsw i32 %mul.2, %add.1
+  %arrayidx6.2 = getelementptr inbounds [1024 x i32], [1024 x i32]* @y, i64 0, i64 %indvars.iv.next.1
+  store i32 %add.2, i32* %arrayidx6.2, align 4
+  %indvars.iv.next.2 = add nuw nsw i64 %indvars.iv, 3
+  %exitcond.2 = icmp eq i64 %indvars.iv.next.2, 1024
+  br i1 %exitcond.2, label %for.cond.cleanup, label %for.body
+}