diff options
| author | Chris Lattner <sabre@nondot.org> | 2008-04-25 04:12:29 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2008-04-25 04:12:29 +0000 |
| commit | eede65ce6cb29c8f3a701be8606e95c9a213efff (patch) | |
| tree | 7ca4d995844361522f706b262efca29ef027329a /lib/Transforms | |
| parent | 877ee973e2d6ade85e38babbd303d96347c7dc8e (diff) | |
Don't infininitely thread branches when a threaded edge
goes back to the block, e.g.:
Threading edge through bool from 'bb37.us.thread3829' to 'bb37.us' with cost: 1, across block:
bb37.us: ; preds = %bb37.us.thread3829, %bb37.us, %bb33
%D1361.1.us = phi i32 [ %tmp36, %bb33 ], [ %D1361.1.us, %bb37.us ], [ 0, %bb37.us.thread3829 ] ; <i32> [#uses=2]
%tmp39.us = icmp eq i32 %D1361.1.us, 0 ; <i1> [#uses=1]
br i1 %tmp39.us, label %bb37.us, label %bb42.us
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50251 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms')
| -rw-r--r-- | lib/Transforms/Scalar/JumpThreading.cpp | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp index 92e40e66d4..be94025404 100644 --- a/lib/Transforms/Scalar/JumpThreading.cpp +++ b/lib/Transforms/Scalar/JumpThreading.cpp @@ -250,6 +250,13 @@ bool JumpThreading::ProcessJumpOnPHI(PHINode *PN) { SuccBB = SI->getSuccessor(SI->findCaseValue(PredCst)); } + // If threading to the same block as we come from, we would infinite loop. + if (SuccBB == BB) { + DOUT << " Not threading BB '" << BB->getNameStart() + << "' - would thread to self!\n"; + return false; + } + // And finally, do it! DOUT << " Threading edge from '" << PredBB->getNameStart() << "' to '" << SuccBB->getNameStart() << "' with cost: " << JumpThreadCost @@ -319,6 +326,13 @@ bool JumpThreading::ProcessBranchOnLogical(Value *V, BasicBlock *BB, // 'true' block. BasicBlock *SuccBB = BB->getTerminator()->getSuccessor(isAnd); + // If threading to the same block as we come from, we would infinite loop. + if (SuccBB == BB) { + DOUT << " Not threading BB '" << BB->getNameStart() + << "' - would thread to self!\n"; + return false; + } + // And finally, do it! DOUT << " Threading edge through bool from '" << PredBB->getNameStart() << "' to '" << SuccBB->getNameStart() << "' with cost: " @@ -390,6 +404,14 @@ bool JumpThreading::ProcessBranchOnCompare(CmpInst *Cmp, BasicBlock *BB) { // Next, get our successor. BasicBlock *SuccBB = BB->getTerminator()->getSuccessor(!TrueDirection); + // If threading to the same block as we come from, we would infinite loop. + if (SuccBB == BB) { + DOUT << " Not threading BB '" << BB->getNameStart() + << "' - would thread to self!\n"; + return false; + } + + // And finally, do it! DOUT << " Threading edge through bool from '" << PredBB->getNameStart() << "' to '" << SuccBB->getNameStart() << "' with cost: " |