From 85c85c5e04b1ca68569f871b7c14342f79a6c741 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sun, 11 Oct 2009 18:39:58 +0000
Subject: [PATCH] when folding duplicate conditions, delete the
 now-probably-dead instruction tree feeding it.

llvm-svn: 83778
---
 llvm/lib/Transforms/Scalar/JumpThreading.cpp  |  2 ++
 llvm/test/Transforms/JumpThreading/basic.ll   | 33 +++++++++++++++++++
 .../test/Transforms/JumpThreading/dup-cond.ll | 30 -----------------
 3 files changed, 35 insertions(+), 30 deletions(-)
 delete mode 100644 llvm/test/Transforms/JumpThreading/dup-cond.ll

diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index 210d6ef5a226..8b11edd891fd 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -450,9 +450,11 @@ bool JumpThreading::ProcessBranchOnDuplicateCond(BasicBlock *PredBB,
           << "' folding condition to '" << BranchDir << "': "
           << *BB->getTerminator() << '\n');
     ++NumFolds;
+    Value *OldCond = DestBI->getCondition();
     DestBI->setCondition(ConstantInt::get(Type::getInt1Ty(BB->getContext()),
                                           BranchDir));
     ConstantFoldTerminator(BB);
+    RecursivelyDeleteTriviallyDeadInstructions(OldCond);
     return true;
   }
  
diff --git a/llvm/test/Transforms/JumpThreading/basic.ll b/llvm/test/Transforms/JumpThreading/basic.ll
index 50433db152da..3d936b8f30fc 100644
--- a/llvm/test/Transforms/JumpThreading/basic.ll
+++ b/llvm/test/Transforms/JumpThreading/basic.ll
@@ -139,3 +139,36 @@ F2:
 	ret i32 %B
 }
 
+
+;; Lexically duplicated conditionals should be threaded.
+
+
+define i32 @test6(i32 %A) {
+; CHECK: @test6
+	%tmp455 = icmp eq i32 %A, 42
+	br i1 %tmp455, label %BB1, label %BB2
+        
+BB2:
+; CHECK: call i32 @f1()
+; CHECK-NEXT: call void @f3()
+; CHECK-NEXT: ret i32 4
+	call i32 @f1()
+	br label %BB1
+        
+
+BB1:
+	%tmp459 = icmp eq i32 %A, 42
+	br i1 %tmp459, label %BB3, label %BB4
+
+BB3:
+	call i32 @f2()
+        ret i32 3
+
+BB4:
+	call void @f3()
+	ret i32 4
+}
+
+
+
+
diff --git a/llvm/test/Transforms/JumpThreading/dup-cond.ll b/llvm/test/Transforms/JumpThreading/dup-cond.ll
deleted file mode 100644
index 0d14c8a54e1f..000000000000
--- a/llvm/test/Transforms/JumpThreading/dup-cond.ll
+++ /dev/null
@@ -1,30 +0,0 @@
-; RUN: opt < %s -jump-threading -die -S | grep icmp | count 1
-
-declare void @f1()
-declare void @f2()
-declare void @f3()
-
-define i32 @test(i32 %A) {
-	%tmp455 = icmp eq i32 %A, 42
-	br i1 %tmp455, label %BB1, label %BB2
-        
-BB2:
-	call void @f1()
-	br label %BB1
-        
-
-BB1:
-	%tmp459 = icmp eq i32 %A, 42
-	br i1 %tmp459, label %BB3, label %BB4
-
-BB3:
-	call void @f2()
-        ret i32 3
-
-BB4:
-	call void @f3()
-	ret i32 4
-}
-
-
-