[llvm] r227390 - Teach SplitBlockPredecessors how to handle landingpad blocks.
Philip Reames
listmail at philipreames.com
Wed Jan 28 15:06:47 PST 2015
Author: reames
Date: Wed Jan 28 17:06:47 2015
New Revision: 227390
URL: http://llvm.org/viewvc/llvm-project?rev=227390&view=rev
Log:
Teach SplitBlockPredecessors how to handle landingpad blocks.
Patch by: Igor Laevsky <igor at azulsystems.com>
"Currently SplitBlockPredecessors generates incorrect code in case if basic block we are going to split has a landingpad. Also seems like it is fairly common case among it's users to conditionally call either SplitBlockPredecessors or SplitLandingPadPredecessors. Because of this I think it is reasonable to add this condition directly into SplitBlockPredecessors."
Differential Revision: http://reviews.llvm.org/D7157
Modified:
llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp
llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp
llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp
llvm/trunk/test/Transforms/LoopSimplify/2011-12-14-LandingpadHeader.ll
Modified: llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h?rev=227390&r1=227389&r2=227390&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h Wed Jan 28 17:06:47 2015
@@ -202,11 +202,15 @@ BasicBlock *SplitEdge(BasicBlock *From,
BasicBlock *SplitBlock(BasicBlock *Old, Instruction *SplitPt,
DominatorTree *DT = nullptr, LoopInfo *LI = nullptr);
-/// SplitBlockPredecessors - This method transforms BB by introducing a new
-/// basic block into the function, and moving some of the predecessors of BB to
-/// be predecessors of the new block. The new predecessors are indicated by the
-/// Preds array, which has NumPreds elements in it. The new block is given a
-/// suffix of 'Suffix'. This function returns the new block.
+/// SplitBlockPredecessors - This method introduces at least one new basic block
+/// into the function and moves some of the predecessors of BB to be
+/// predecessors of the new block. The new predecessors are indicated by the
+/// Preds array. The new block is given a suffix of 'Suffix'. Returns new basic
+/// block to which predecessors from Preds are now pointing.
+///
+/// If BB is a landingpad block then additional basicblock might be introduced.
+/// It will have Suffix+".split_lp". See SplitLandingPadPredecessors for more
+/// details on this case.
///
/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree,
/// DominanceFrontier, LoopInfo, and LCCSA but no other analyses.
Modified: llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp?rev=227390&r1=227389&r2=227390&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp Wed Jan 28 17:06:47 2015
@@ -769,16 +769,9 @@ void LoopUnswitch::SplitExitEdges(Loop *
// Although SplitBlockPredecessors doesn't preserve loop-simplify in
// general, if we call it on all predecessors of all exits then it does.
- if (!ExitBlock->isLandingPad()) {
- SplitBlockPredecessors(ExitBlock, Preds, ".us-lcssa",
- /*AliasAnalysis*/ nullptr, DT, LI,
- /*PreserveLCSSA*/ true);
- } else {
- SmallVector<BasicBlock*, 2> NewBBs;
- SplitLandingPadPredecessors(ExitBlock, Preds, ".us-lcssa", ".us-lcssa",
- NewBBs, /*AliasAnalysis*/ nullptr, DT, LI,
- /*PreserveLCSSA*/ true);
- }
+ SplitBlockPredecessors(ExitBlock, Preds, ".us-lcssa",
+ /*AliasAnalysis*/ nullptr, DT, LI,
+ /*PreserveLCSSA*/ true);
}
}
Modified: llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp?rev=227390&r1=227389&r2=227390&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp Wed Jan 28 17:06:47 2015
@@ -454,11 +454,15 @@ static void UpdatePHINodes(BasicBlock *O
}
}
-/// SplitBlockPredecessors - This method transforms BB by introducing a new
-/// basic block into the function, and moving some of the predecessors of BB to
-/// be predecessors of the new block. The new predecessors are indicated by the
-/// Preds array, which has NumPreds elements in it. The new block is given a
-/// suffix of 'Suffix'.
+/// SplitBlockPredecessors - This method introduces at least one new basic block
+/// into the function and moves some of the predecessors of BB to be
+/// predecessors of the new block. The new predecessors are indicated by the
+/// Preds array. The new block is given a suffix of 'Suffix'. Returns new basic
+/// block to which predecessors from Preds are now pointing.
+///
+/// If BB is a landingpad block then additional basicblock might be introduced.
+/// It will have suffix of 'Suffix'+".split_lp".
+/// See SplitLandingPadPredecessors for more details on this case.
///
/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree,
/// LoopInfo, and LCCSA but no other analyses. In particular, it does not
@@ -470,6 +474,17 @@ BasicBlock *llvm::SplitBlockPredecessors
const char *Suffix, AliasAnalysis *AA,
DominatorTree *DT, LoopInfo *LI,
bool PreserveLCSSA) {
+ // For the landingpads we need to act a bit differently.
+ // Delegate this work to the SplitLandingPadPredecessors.
+ if (BB->isLandingPad()) {
+ SmallVector<BasicBlock*, 2> NewBBs;
+ std::string NewName = std::string(Suffix) + ".split-lp";
+
+ SplitLandingPadPredecessors(BB, Preds, Suffix, NewName.c_str(),
+ NewBBs, AA, DT, LI, PreserveLCSSA);
+ return NewBBs[0];
+ }
+
// Create new basic block, insert right before the original block.
BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), BB->getName()+Suffix,
BB->getParent(), BB);
Modified: llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp?rev=227390&r1=227389&r2=227390&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp Wed Jan 28 17:06:47 2015
@@ -139,15 +139,8 @@ BasicBlock *llvm::InsertPreheaderForLoop
// Split out the loop pre-header.
BasicBlock *PreheaderBB;
- if (!Header->isLandingPad()) {
- PreheaderBB = SplitBlockPredecessors(Header, OutsideBlocks, ".preheader",
- AA, DT, LI, PreserveLCSSA);
- } else {
- SmallVector<BasicBlock*, 2> NewBBs;
- SplitLandingPadPredecessors(Header, OutsideBlocks, ".preheader",
- ".split-lp", NewBBs, AA, DT, LI, PreserveLCSSA);
- PreheaderBB = NewBBs[0];
- }
+ PreheaderBB = SplitBlockPredecessors(Header, OutsideBlocks, ".preheader",
+ AA, DT, LI, PreserveLCSSA);
PreheaderBB->getTerminator()->setDebugLoc(
Header->getFirstNonPHI()->getDebugLoc());
@@ -184,15 +177,8 @@ static BasicBlock *rewriteLoopExitBlock(
bool PreserveLCSSA = PP->mustPreserveAnalysisID(LCSSAID);
- if (Exit->isLandingPad()) {
- SmallVector<BasicBlock*, 2> NewBBs;
- SplitLandingPadPredecessors(Exit, LoopBlocks, ".loopexit", ".nonloopexit",
- NewBBs, AA, DT, LI, PreserveLCSSA);
- NewExitBB = NewBBs[0];
- } else {
- NewExitBB = SplitBlockPredecessors(Exit, LoopBlocks, ".loopexit", AA, DT,
- LI, PreserveLCSSA);
- }
+ NewExitBB = SplitBlockPredecessors(Exit, LoopBlocks, ".loopexit", AA, DT,
+ LI, PreserveLCSSA);
DEBUG(dbgs() << "LoopSimplify: Creating dedicated exit block "
<< NewExitBB->getName() << "\n");
Modified: llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp?rev=227390&r1=227389&r2=227390&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp Wed Jan 28 17:06:47 2015
@@ -119,15 +119,8 @@ static void ConnectProlog(Loop *L, Value
assert(Exit && "Loop must have a single exit block only");
// Split the exit to maintain loop canonicalization guarantees
SmallVector<BasicBlock*, 4> Preds(pred_begin(Exit), pred_end(Exit));
- if (!Exit->isLandingPad()) {
- SplitBlockPredecessors(Exit, Preds, ".unr-lcssa", AA, DT, LI,
- P->mustPreserveAnalysisID(LCSSAID));
- } else {
- SmallVector<BasicBlock*, 2> NewBBs;
- SplitLandingPadPredecessors(Exit, Preds, ".unr1-lcssa", ".unr2-lcssa",
- NewBBs, AA, DT, LI,
- P->mustPreserveAnalysisID(LCSSAID));
- }
+ SplitBlockPredecessors(Exit, Preds, ".unr-lcssa", AA, DT, LI,
+ P->mustPreserveAnalysisID(LCSSAID));
// Add the branch to the exit block (around the unrolled loop)
BranchInst::Create(Exit, NewPH, BrLoopExit, InsertPt);
InsertPt->eraseFromParent();
Modified: llvm/trunk/test/Transforms/LoopSimplify/2011-12-14-LandingpadHeader.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopSimplify/2011-12-14-LandingpadHeader.ll?rev=227390&r1=227389&r2=227390&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopSimplify/2011-12-14-LandingpadHeader.ll (original)
+++ llvm/trunk/test/Transforms/LoopSimplify/2011-12-14-LandingpadHeader.ll Wed Jan 28 17:06:47 2015
@@ -12,7 +12,7 @@ entry:
; CHECK-NEXT: landingpad
; CHECK: br label %catch
-; CHECK: catch.split-lp:
+; CHECK: catch.preheader.split-lp:
; CHECK-NEXT: landingpad
; CHECK: br label %catch
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