[LoopSimplify] Improve a test for loop simplify minorly. NFC.

I did some basic testing while looking for a bug in my recent change to
loop simplify and even though it didn't find the bug it seems like
a useful improvement anyways.

llvm-svn: 306256

1 files changed, 150 insertions, 12 deletions

diff --git a/llvm/test/Transforms/LoopSimplify/basictest.ll b/llvm/test/Transforms/LoopSimplify/basictest.ll
index 81b2c80fae0..191e2b2797c 100644
--- a/llvm/test/Transforms/LoopSimplify/basictest.ll
+++ b/llvm/test/Transforms/LoopSimplify/basictest.ll
@@ -1,17 +1,155 @@
-; RUN: opt < %s -loop-simplify
-; RUN: opt < %s -passes=loop-simplify
+; RUN: opt < %s -S -loop-simplify | FileCheck %s
+; RUN: opt < %s -S -passes=loop-simplify | FileCheck %s
 
-; This function should get a preheader inserted before BB3, that is jumped
-; to by BB1 & BB2
+; This function should get a preheader inserted before bb3, that is jumped
+; to by bb1 & bb2
+define void @test() {
+; CHECK-LABEL: define void @test(
+entry:
+  br i1 true, label %bb1, label %bb2
+
+bb1:
+  br label %bb3
+; CHECK:      bb1:
+; CHECK-NEXT:   br label %[[PH:.*]]
+
+bb2:
+  br label %bb3
+; CHECK:      bb2:
+; CHECK-NEXT:   br label %[[PH]]
+
+bb3:
+  br label %bb3
+; CHECK:      [[PH]]:
+; CHECK-NEXT:   br label %bb3
 ;
+; CHECK:      bb3:
+; CHECK-NEXT:   br label %bb3
+}
 
-define void @test() {
-	br i1 true, label %BB1, label %BB2
-BB1:		; preds = %0
-	br label %BB3
-BB2:		; preds = %0
-	br label %BB3
-BB3:		; preds = %BB3, %BB2, %BB1
-	br label %BB3
+; Test a case where we have multiple exit blocks as successors of a single loop
+; block that need to be made dedicated exit blocks. We also have multiple
+; exiting edges to one of the exit blocks that all should be rewritten.
+define void @test_multiple_exits_from_single_block(i8 %a, i8* %b.ptr) {
+; CHECK-LABEL: define void @test_multiple_exits_from_single_block(
+entry:
+  switch i8 %a, label %loop [
+    i8 0, label %exit.a
+    i8 1, label %exit.b
+  ]
+; CHECK:      entry:
+; CHECK-NEXT:   switch i8 %a, label %[[PH:.*]] [
+; CHECK-NEXT:     i8 0, label %exit.a
+; CHECK-NEXT:     i8 1, label %exit.b
+; CHECK-NEXT:   ]
+
+loop:
+  %b = load volatile i8, i8* %b.ptr
+  switch i8 %b, label %loop [
+    i8 0, label %exit.a
+    i8 1, label %exit.b
+    i8 2, label %loop
+    i8 3, label %exit.a
+    i8 4, label %loop
+    i8 5, label %exit.a
+    i8 6, label %loop
+  ]
+; CHECK:      [[PH]]:
+; CHECK-NEXT:   br label %loop
+;
+; CHECK:      loop:
+; CHECK-NEXT:   %[[B:.*]] = load volatile i8, i8* %b.ptr
+; CHECK-NEXT:   switch i8 %[[B]], label %[[BACKEDGE:.*]] [
+; CHECK-NEXT:     i8 0, label %[[LOOPEXIT_A:.*]]
+; CHECK-NEXT:     i8 1, label %[[LOOPEXIT_B:.*]]
+; CHECK-NEXT:     i8 2, label %[[BACKEDGE]]
+; CHECK-NEXT:     i8 3, label %[[LOOPEXIT_A]]
+; CHECK-NEXT:     i8 4, label %[[BACKEDGE]]
+; CHECK-NEXT:     i8 5, label %[[LOOPEXIT_A]]
+; CHECK-NEXT:     i8 6, label %[[BACKEDGE]]
+; CHECK-NEXT:   ]
+;
+; CHECK:      [[BACKEDGE]]:
+; CHECK-NEXT:   br label %loop
+
+exit.a:
+  ret void
+; CHECK:      [[LOOPEXIT_A]]:
+; CHECK-NEXT:   br label %exit.a
+;
+; CHECK:      exit.a:
+; CHECK-NEXT:   ret void
+
+exit.b:
+  ret void
+; CHECK:      [[LOOPEXIT_B]]:
+; CHECK-NEXT:   br label %exit.b
+;
+; CHECK:      exit.b:
+; CHECK-NEXT:   ret void
 }
 
+; Check that we leave already dedicated exits alone when forming dedicated exit
+; blocks.
+define void @test_pre_existing_dedicated_exits(i1 %a, i1* %ptr) {
+; CHECK-LABEL: define void @test_pre_existing_dedicated_exits(
+entry:
+  br i1 %a, label %loop.ph, label %non_dedicated_exit
+; CHECK:      entry:
+; CHECK-NEXT:   br i1 %a, label %loop.ph, label %non_dedicated_exit
+
+loop.ph:
+  br label %loop.header
+; CHECK:      loop.ph:
+; CHECK-NEXT:   br label %loop.header
+
+loop.header:
+  %c1 = load volatile i1, i1* %ptr
+  br i1 %c1, label %loop.body1, label %dedicated_exit1
+; CHECK:      loop.header:
+; CHECK-NEXT:   %[[C1:.*]] = load volatile i1, i1* %ptr
+; CHECK-NEXT:   br i1 %[[C1]], label %loop.body1, label %dedicated_exit1
+
+loop.body1:
+  %c2 = load volatile i1, i1* %ptr
+  br i1 %c2, label %loop.body2, label %non_dedicated_exit
+; CHECK:      loop.body1:
+; CHECK-NEXT:   %[[C2:.*]] = load volatile i1, i1* %ptr
+; CHECK-NEXT:   br i1 %[[C2]], label %loop.body2, label %[[LOOPEXIT:.*]]
+
+loop.body2:
+  %c3 = load volatile i1, i1* %ptr
+  br i1 %c3, label %loop.backedge, label %dedicated_exit2
+; CHECK:      loop.body2:
+; CHECK-NEXT:   %[[C3:.*]] = load volatile i1, i1* %ptr
+; CHECK-NEXT:   br i1 %[[C3]], label %loop.backedge, label %dedicated_exit2
+
+loop.backedge:
+  br label %loop.header
+; CHECK:      loop.backedge:
+; CHECK-NEXT:   br label %loop.header
+
+dedicated_exit1:
+  ret void
+; Check that there isn't a split loop exit.
+; CHECK-NOT:    br label %dedicated_exit1
+;
+; CHECK:      dedicated_exit1:
+; CHECK-NEXT:   ret void
+
+dedicated_exit2:
+  ret void
+; Check that there isn't a split loop exit.
+; CHECK-NOT:    br label %dedicated_exit2
+;
+; CHECK:      dedicated_exit2:
+; CHECK-NEXT:   ret void
+
+non_dedicated_exit:
+  ret void
+; CHECK:      [[LOOPEXIT]]:
+; CHECK-NEXT:   br label %non_dedicated_exit
+;
+; CHECK:      non_dedicated_exit:
+; CHECK-NEXT:   ret void
+}