From 602fc20596c891a8a2b9ab244a2e3b2efae32aa9 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Thu, 9 Feb 2006 22:15:42 +0000 Subject: [PATCH] Simplify control flow a bit, note that unswitch preserves canonical loop form llvm-svn: 26098 --- lib/Transforms/Scalar/LoopUnswitch.cpp | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp index 850be78f808..273291910b3 100644 --- a/lib/Transforms/Scalar/LoopUnswitch.cpp +++ b/lib/Transforms/Scalar/LoopUnswitch.cpp @@ -59,12 +59,13 @@ namespace { /// virtual void getAnalysisUsage(AnalysisUsage &AU) const { AU.addRequiredID(LoopSimplifyID); + AU.addPreservedID(LoopSimplifyID); AU.addRequired(); AU.addPreserved(); } private: - void VersionLoop(Value *LIC, Loop *L); + void VersionLoop(Value *LIC, Loop *L, Loop *&Out1, Loop *&Out2); BasicBlock *SplitBlock(BasicBlock *BB, bool SplitAtTop); void RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC, bool Val); }; @@ -172,11 +173,13 @@ bool LoopUnswitch::visitLoop(Loop *L) { } //std::cerr << "BEFORE:\n"; LI->dump(); - VersionLoop(BI->getCondition(), L); + Loop *First = 0, *Second = 0; + VersionLoop(BI->getCondition(), L, First, Second); //std::cerr << "AFTER:\n"; LI->dump(); - // FIXME: Why return here? What if we have: - // "for () { if (iv1) { if (iv2) { } } }" ? + // Try to unswitch each of our new loops now! + if (First) visitLoop(First); + if (Second) visitLoop(Second); return true; } @@ -247,8 +250,9 @@ static Loop *CloneLoop(Loop *L, Loop *PL, std::map &VM, /// VersionLoop - We determined that the loop is profitable to unswitch and /// contains a branch on a loop invariant condition. Split it into loop -/// versions and test the condition outside of either loop. -void LoopUnswitch::VersionLoop(Value *LIC, Loop *L) { +/// versions and test the condition outside of either loop. Return the loops +/// created as Out1/Out2. +void LoopUnswitch::VersionLoop(Value *LIC, Loop *L, Loop *&Out1, Loop *&Out2) { Function *F = L->getHeader()->getParent(); DEBUG(std::cerr << "loop-unswitch: Unswitching loop %" @@ -324,10 +328,8 @@ void LoopUnswitch::VersionLoop(Value *LIC, Loop *L) { RewriteLoopBodyWithConditionConstant(L, LIC, true); RewriteLoopBodyWithConditionConstant(NewLoop, LIC, false); ++NumUnswitched; - - // Try to unswitch each of our new loops now! - visitLoop(L); - visitLoop(NewLoop); + Out1 = L; + Out2 = NewLoop; } // RewriteLoopBodyWithConditionConstant - We know that the boolean value LIC has