MachineSink: Sort the successors before trying to find SuccToSinkTo.

One motivating example is to sink an instruction from a basic block which has
two successors: one outside the loop, the other inside the loop. We should try
to sink the instruction outside the loop.

rdar://11980766


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161062 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 54 insertions, 0 deletions

diff --git a/test/CodeGen/X86/sink-out-of-loop.ll b/test/CodeGen/X86/sink-out-of-loop.ll
new file mode 100644
index 0000000000..c600f925a3
--- /dev/null
+++ b/test/CodeGen/X86/sink-out-of-loop.ll
@@ -0,0 +1,54 @@
+; RUN: llc -mtriple=x86_64-apple-darwin < %s | FileCheck %s
+
+; A MOV32ri is inside a loop, it has two successors, one successor is inside the
+; same loop, the other successor is outside the loop. We should be able to sink
+; MOV32ri outside the loop.
+; rdar://11980766
+define i32 @sink_succ(i32 %argc, i8** nocapture %argv) nounwind uwtable ssp {
+; CHECK: sink_succ
+; CHECK: [[OUTER_LN1:LBB0_[0-9]+]]: ## %preheader
+; CHECK: %exit
+; CHECK-NOT: movl
+; CHECK: jne [[OUTER_LN1]]
+; CHECK: movl
+; CHECK: [[LN2:LBB0_[0-9]+]]: ## %for.body2
+; CHECK: jne [[LN2]]
+; CHECK: ret
+entry:
+  br label %preheader
+
+preheader:
+  %i.127 = phi i32 [ 0, %entry ], [ %inc9, %exit ]
+  br label %for.body1.lr
+
+for.body1.lr:
+  %iv30 = phi i32 [ 1, %preheader ], [ %iv.next31, %for.inc40.i ]
+  br label %for.body1
+
+for.body1:
+  %iv.i = phi i64 [ 0, %for.body1.lr ], [ %iv.next.i, %for.body1 ]
+  %iv.next.i = add i64 %iv.i, 1
+  %lftr.wideiv32 = trunc i64 %iv.next.i to i32
+  %exitcond33 = icmp eq i32 %lftr.wideiv32, %iv30
+  br i1 %exitcond33, label %for.inc40.i, label %for.body1
+
+for.inc40.i:
+  %iv.next31 = add i32 %iv30, 1
+  %exitcond49.i = icmp eq i32 %iv.next31, 32
+  br i1 %exitcond49.i, label %exit, label %for.body1.lr
+
+exit:
+  %inc9 = add nsw i32 %i.127, 1
+  %exitcond34 = icmp eq i32 %inc9, 10
+  br i1 %exitcond34, label %for.body2, label %preheader
+
+for.body2:
+  %iv = phi i64 [ %iv.next, %for.body2 ], [ 0, %exit ]
+  %iv.next = add i64 %iv, 1
+  %lftr.wideiv = trunc i64 %iv.next to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, 2048
+  br i1 %exitcond, label %for.end20, label %for.body2
+
+for.end20:
+  ret i32 0
+}