make jump threading recursively simplify expressions instead of doing it

just one level deep.  On the testcase we go from getting this:

F1:                                               ; preds = %T2
  %F = and i1 true, %cond                         ; <i1> [#uses=1]
  br i1 %F, label %X, label %Y

to a fully threaded:

F1:                                               ; preds = %T2
  br label %Y


This changes gets us to the point where we're forming (too many) switch 
instructions on doug's strswitch testcase.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86646 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 32 insertions, 0 deletions

diff --git a/test/Transforms/JumpThreading/basic.ll b/test/Transforms/JumpThreading/basic.ll
index 7b444ad..1be086b 100644
--- a/test/Transforms/JumpThreading/basic.ll
+++ b/test/Transforms/JumpThreading/basic.ll
@@ -203,3 +203,35 @@ F2:
 ; CHECK-NEXT: phi i32
 }
 
+
+declare i1 @test8a()
+
+define i32 @test8b(i1 %cond, i1 %cond2) {
+; CHECK: @test8b
+T0:
+        %A = call i1 @test8a()
+	br i1 %A, label %T1, label %F1
+T1:
+        %B = call i1 @test8a()
+	br i1 %B, label %T2, label %F1
+T2:
+        %C = call i1 @test8a()
+	br i1 %cond, label %T3, label %F1
+T3:
+        ret i32 0
+
+F1:
+; TODO: F1 uncond branch block should be removed, T2 should jump directly to Y.
+; CHECK: F1:
+; CHECK-NEXT br label %Y
+        %D = phi i32 [0, %T0], [0, %T1], [1, %T2]
+        %E = icmp eq i32 %D, 1
+        %F = and i1 %E, %cond
+	br i1 %F, label %X, label %Y
+X:
+        call i1 @test8a()
+        ret i32 1
+Y:
+        ret i32 2
+}
+