[llvm-commits] [llvm] r56286 - in /llvm/trunk: lib/Transforms/Utils/SimplifyCFG.cpp test/Transforms/SimplifyCFG/2008-09-17-SpeculativeHoist.ll

[Devang Patel]

Author: dpatel
Date: Wed Sep 17 13:21:49 2008
New Revision: 56286

URL: http://llvm.org/viewvc/llvm-project?rev=56286&view=rev
Log:
Do not hoist instruction above branch condition. The instruction may use branch condition.

Added:
    llvm/trunk/test/Transforms/SimplifyCFG/2008-09-17-SpeculativeHoist.ll
Modified:
    llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp

Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=56286&r1=56285&r2=56286&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Wed Sep 17 13:21:49 2008
@@ -1046,15 +1046,8 @@
       return false;
   }
 
-  // If we get here, we can hoist the instruction. Try to place it before the
-  // icmp instruction preceeding the conditional branch.
-  BasicBlock::iterator InsertPos = BI;
-  if (InsertPos != BIParent->begin())
-    --InsertPos;
-  if (InsertPos == BrCond && !isa<PHINode>(BrCond))
-    BIParent->getInstList().splice(InsertPos, BB1->getInstList(), I);
-  else
-    BIParent->getInstList().splice(BI, BB1->getInstList(), I);
+  // If we get here, we can hoist the instruction. 
+  BIParent->getInstList().splice(BI, BB1->getInstList(), I);
 
   // Create a select whose true value is the speculatively executed value and
   // false value is the previously determined FalseV.

Added: llvm/trunk/test/Transforms/SimplifyCFG/2008-09-17-SpeculativeHoist.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/2008-09-17-SpeculativeHoist.ll?rev=56286&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/2008-09-17-SpeculativeHoist.ll (added)
+++ llvm/trunk/test/Transforms/SimplifyCFG/2008-09-17-SpeculativeHoist.ll Wed Sep 17 13:21:49 2008
@@ -0,0 +1,18 @@
+; RUN: llvm-as < %s | opt -simplifycfg -disable-output
+; PR 2800
+
+define void @foo() {
+start:
+	%tmp = call i1 @bar( )		; <i1> [#uses=4]
+	br i1 %tmp, label %brtrue, label %brfalse
+
+brtrue:		; preds = %start
+	%tmpnew = and i1 %tmp, %tmp		; <i1> [#uses=1]
+	br label %brfalse
+
+brfalse:		; preds = %brtrue, %start
+	%andandtmp.0 = phi i1 [ %tmp, %start ], [ %tmpnew, %brtrue ]		; <i1> [#uses=0]
+	ret void
+}
+
+declare i1 @bar()