StructurizeCFG: Use LoopInfo analysis for better loop detection

We were assuming that each back-edge in a region represented a unique
loop, which is not always the case.  We need to use LoopInfo to
correctly determine which back-edges are loops.

llvm-svn: 223199

1 files changed, 41 insertions, 0 deletions

diff --git a/llvm/test/Transforms/StructurizeCFG/one-loop-multiple-backedges.ll b/llvm/test/Transforms/StructurizeCFG/one-loop-multiple-backedges.ll
new file mode 100644
index 00000000000..8ebd47aefd1
--- /dev/null
+++ b/llvm/test/Transforms/StructurizeCFG/one-loop-multiple-backedges.ll
@@ -0,0 +1,41 @@
+; RUN: opt -S -structurizecfg %s -o - | FileCheck %s
+
+; CHECK-NOT: br i1 true
+
+define void @blam(i32 addrspace(1)* nocapture %arg, float %arg1, float %arg2) {
+; CHECK: bb:
+bb:
+  br label %bb3
+
+; CHECK: bb3:
+bb3:                                              ; preds = %bb7, %bb
+  %tmp = phi i64 [ 0, %bb ], [ %tmp8, %bb7 ]
+  %tmp4 = fcmp ult float %arg1, 3.500000e+00
+; CHECK: br i1 %tmp4, label %bb7, label %Flow
+  br i1 %tmp4, label %bb7, label %bb5
+
+; CHECK: Flow:
+; CHECK: br i1 %2, label %Flow1, label %bb3
+
+; CHECK: Flow1:
+; CHECK: br i1 %3, label %bb5, label %bb10
+
+; CHECK: bb5:
+bb5:                                              ; preds = %bb3
+  %tmp6 = fcmp olt float 0.000000e+00, %arg2
+; CHECK: br label %bb10
+  br i1 %tmp6, label %bb10, label %bb7
+
+; CHECK: bb7
+bb7:                                              ; preds = %bb5, %bb3
+  %tmp8 = add nuw nsw i64 %tmp, 1
+  %tmp9 = icmp slt i64 %tmp8, 5
+; CHECK: br label %Flow
+  br i1 %tmp9, label %bb3, label %bb10
+
+; CHECK: bb10
+bb10:                                             ; preds = %bb7, %bb5
+  %tmp11 = phi i32 [ 15, %bb5 ], [ 255, %bb7 ]
+  store i32 %tmp11, i32 addrspace(1)* %arg, align 4
+  ret void
+}