3 files changed, 74 insertions, 2 deletions
diff --git a/llvm/test/CodeGen/AArch64/arm64-extload-knownzero.ll b/llvm/test/CodeGen/AArch64/arm64-extload-knownzero.ll
index 92ce2a04589..5dd8cb28232 100644
--- a/llvm/test/CodeGen/AArch64/arm64-extload-knownzero.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-extload-knownzero.ll
@@ -12,7 +12,6 @@ bb1:
   %tmp2 = load i16, i16* %ptr, align 2
   br label %bb2
 bb2:
-; CHECK: %bb2
 ; CHECK-NOT: and {{w[0-9]+}}, [[REG]], #0xffff
 ; CHECK: cmp [[REG]], #23
   %tmp3 = phi i16 [ 0, %entry ], [ %tmp2, %bb1 ]
diff --git a/llvm/test/CodeGen/AArch64/machine_cse.ll b/llvm/test/CodeGen/AArch64/machine_cse.ll
index 032199e6218..e9fa68041d9 100644
--- a/llvm/test/CodeGen/AArch64/machine_cse.ll
+++ b/llvm/test/CodeGen/AArch64/machine_cse.ll
@@ -1,4 +1,8 @@
-; RUN: llc < %s -mtriple=aarch64-linux-gnuabi -O2 | FileCheck %s
+; RUN: llc < %s -mtriple=aarch64-linux-gnuabi -O2 -tail-dup-placement=0 | FileCheck %s
+; -tail-dup-placement causes tail duplication during layout. This breaks the
+; assumptions of the test case as written (specifically, it creates an
+; additional cmp instruction, creating a false positive), so we pass
+; -tail-dup-placement=0 to restore the original behavior
 
 ; marked as external to prevent possible optimizations
 @a = external global i32
diff --git a/llvm/test/CodeGen/AArch64/tail-dup-repeat-worklist.ll b/llvm/test/CodeGen/AArch64/tail-dup-repeat-worklist.ll
new file mode 100644
index 00000000000..c2997c50f4d
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/tail-dup-repeat-worklist.ll
@@ -0,0 +1,69 @@
+; RUN: llc -O3 -o - -verify-machineinstrs %s | FileCheck %s
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64-unknown-linux-gnu"
+
+%struct.s1 = type { %struct.s3*, %struct.s1* }
+%struct.s2 = type opaque
+%struct.s3 = type { i32 }
+
+; Function Attrs: nounwind
+define internal fastcc i32 @repeated_dup_worklist(%struct.s1** %pp1, %struct.s2* %p2, i32 %state, i1 %i1_1, i32 %i32_1) unnamed_addr #0 {
+entry:
+  br label %while.cond.outer
+
+; The loop gets laid out:
+; %while.cond.outer
+; %(null)
+; %(null)
+; %dup2
+; and then %dup1 gets chosen as the next block.
+; when dup2 is duplicated into dup1, %worklist could erroneously be placed on
+; the worklist, because all of its current predecessors are now scheduled.
+; However, after dup2 is tail-duplicated, %worklist can't be on the worklist
+; because it now has unscheduled predecessors.q
+; CHECK-LABEL: repeated_dup_worklist
+; CHECK: // %entry
+; CHECK: // %while.cond.outer
+; first %(null) block
+; CHECK: // in Loop:
+; CHECK: ldr
+; CHECK-NEXT: tbnz
+; second %(null) block
+; CHECK: // in Loop:
+; CHECK: // %dup2
+; CHECK: // %worklist
+; CHECK: // %if.then96.i
+while.cond.outer:                                 ; preds = %dup1, %entry
+  %progress.0.ph = phi i32 [ 0, %entry ], [ %progress.1, %dup1 ]
+  %inc77 = add nsw i32 %progress.0.ph, 1
+  %cmp = icmp slt i32 %progress.0.ph, %i32_1
+  br i1 %cmp, label %dup2, label %dup1
+
+dup2:                       ; preds = %if.then96.i, %worklist, %while.cond.outer
+  %progress.1.ph = phi i32 [ 0, %while.cond.outer ], [ %progress.1, %if.then96.i ], [ %progress.1, %worklist ]
+  %.pr = load %struct.s1*, %struct.s1** %pp1, align 8
+  br label %dup1
+
+dup1:                                       ; preds = %dup2, %while.cond.outer
+  %0 = phi %struct.s1* [ %.pr, %dup2 ], [ undef, %while.cond.outer ]
+  %progress.1 = phi i32 [ %progress.1.ph, %dup2 ], [ %inc77, %while.cond.outer ]
+  br i1 %i1_1, label %while.cond.outer, label %worklist
+
+worklist:                                       ; preds = %dup1
+  %snode94 = getelementptr inbounds %struct.s1, %struct.s1* %0, i64 0, i32 0
+  %1 = load %struct.s3*, %struct.s3** %snode94, align 8
+  %2 = getelementptr inbounds %struct.s3, %struct.s3* %1, i32 0, i32 0
+  %3 = load i32, i32* %2, align 4
+  %tobool95.i = icmp eq i32 %3, 0
+  br i1 %tobool95.i, label %if.then96.i, label %dup2
+
+if.then96.i:                                      ; preds = %worklist
+  call fastcc void @free_s3(%struct.s2* %p2, %struct.s3* %1) #1
+  br label %dup2
+}
+
+; Function Attrs: nounwind
+declare fastcc void @free_s3(%struct.s2*, %struct.s3*) unnamed_addr #0
+
+attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="cortex-a57" "target-features"="+crc,+crypto,+neon" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind }