[llvm] r347289 - Recommit "[LoopSimplifyCFG] Teach LoopSimplifyCFG to constant-fold branches and switches"
Mikael Holmén via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 22 23:42:03 PST 2018
Hi Max,
With this commit the following starts crashing:
opt -o /dev/null bbi-21357.ll -loop-simplifycfg -loop-deletion
I get:
opt: ../lib/Transforms/Scalar/LoopDeletion.cpp:138: LoopDeletionResult
deleteLoopIfDead(llvm::Loop *, llvm::DominatorTree &,
llvm::ScalarEvolution &, llvm::LoopInfo &): Assertion
`L->isLCSSAForm(DT) && "Expected LCSSA!"' failed.
Stack dump:
0. Program arguments: build-all/bin/opt -o /dev/null bbi-21357.ll
-loop-simplifycfg -loop-deletion
1. Running pass 'Function Pass Manager' on module 'bbi-21357.ll'.
2. Running pass 'Loop Pass Manager' on function '@f1'
3. Running pass 'Delete dead loops' on basic block '%bb1'
#0 0x00000000021e8eb4 PrintStackTraceSignalHandler(void*)
(build-all/bin/opt+0x21e8eb4)
#1 0x00000000021e6fe0 llvm::sys::RunSignalHandlers()
(build-all/bin/opt+0x21e6fe0)
#2 0x00000000021e9218 SignalHandler(int) (build-all/bin/opt+0x21e9218)
#3 0x00007f6880ec6330 __restore_rt
(/lib/x86_64-linux-gnu/libpthread.so.0+0x10330)
#4 0x00007f687fab5c37 gsignal
/build/eglibc-ripdx6/eglibc-2.19/signal/../nptl/sysdeps/unix/sysv/linux/raise.c:56:0
#5 0x00007f687fab9028 abort
/build/eglibc-ripdx6/eglibc-2.19/stdlib/abort.c:91:0
#6 0x00007f687faaebf6 __assert_fail_base
/build/eglibc-ripdx6/eglibc-2.19/assert/assert.c:92:0
#7 0x00007f687faaeca2 (/lib/x86_64-linux-gnu/libc.so.6+0x2fca2)
#8 0x0000000001ffa3a4 deleteLoopIfDead(llvm::Loop*,
llvm::DominatorTree&, llvm::ScalarEvolution&, llvm::LoopInfo&)
(build-all/bin/opt+0x1ffa3a4)
#9 0x0000000001ffa8b6 (anonymous
namespace)::LoopDeletionLegacyPass::runOnLoop(llvm::Loop*,
llvm::LPPassManager&) (build-all/bin/opt+0x1ffa8b6)
#10 0x000000000167a58c
llvm::LPPassManager::runOnFunction(llvm::Function&)
(build-all/bin/opt+0x167a58c)
#11 0x0000000001c0797d
llvm::FPPassManager::runOnFunction(llvm::Function&)
(build-all/bin/opt+0x1c0797d)
#12 0x0000000001c07c38 llvm::FPPassManager::runOnModule(llvm::Module&)
(build-all/bin/opt+0x1c07c38)
#13 0x0000000001c0809a llvm::legacy::PassManagerImpl::run(llvm::Module&)
(build-all/bin/opt+0x1c0809a)
#14 0x000000000077b08b main (build-all/bin/opt+0x77b08b)
#15 0x00007f687faa0f45 __libc_start_main
/build/eglibc-ripdx6/eglibc-2.19/csu/libc-start.c:321:0
#16 0x00000000007605fd _start (build-all/bin/opt+0x7605fd)
I've seen a couple of other failures too recently, e.g.
PHINode should have one entry for each predecessor of its parent basic
block!
and also
opt: ../lib/Transforms/Scalar/IndVarSimplify.cpp:2585: bool (anonymous
namespace)::IndVarSimplify::run(llvm::Loop *): Assertion
`L->isRecursivelyLCSSAForm(*DT, *LI) && "LCSSA required to run
indvars!"' failed."
but I haven't reduced and really verified they are due to this commit yet.
/Mikael
On 11/20/18 6:43 AM, Max Kazantsev via llvm-commits wrote:
> Author: mkazantsev
> Date: Mon Nov 19 21:43:32 2018
> New Revision: 347289
>
> URL: http://llvm.org/viewvc/llvm-project?rev=347289&view=rev
> Log:
> Recommit "[LoopSimplifyCFG] Teach LoopSimplifyCFG to constant-fold branches and switches"
>
> The initial version of patch lacked Phi nodes updates in destinations of removed
> edges. This version contains this update and tests on this situation.
>
> Differential Revision: https://reviews.llvm.org/D54021
>
> Modified:
> llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
> llvm/trunk/test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll
>
> Modified: llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp?rev=347289&r1=347288&r2=347289&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp Mon Nov 19 21:43:32 2018
> @@ -41,6 +41,318 @@ using namespace llvm;
>
> #define DEBUG_TYPE "loop-simplifycfg"
>
> +STATISTIC(NumTerminatorsFolded,
> + "Number of terminators folded to unconditional branches");
> +
> +/// If \p BB is a switch or a conditional branch, but only one of its successors
> +/// can be reached from this block in runtime, return this successor. Otherwise,
> +/// return nullptr.
> +static BasicBlock *getOnlyLiveSuccessor(BasicBlock *BB) {
> + Instruction *TI = BB->getTerminator();
> + if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
> + if (BI->isUnconditional())
> + return nullptr;
> + if (BI->getSuccessor(0) == BI->getSuccessor(1))
> + return BI->getSuccessor(0);
> + ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
> + if (!Cond)
> + return nullptr;
> + return Cond->isZero() ? BI->getSuccessor(1) : BI->getSuccessor(0);
> + }
> +
> + if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
> + auto *CI = dyn_cast<ConstantInt>(SI->getCondition());
> + if (!CI)
> + return nullptr;
> + for (auto Case : SI->cases())
> + if (Case.getCaseValue() == CI)
> + return Case.getCaseSuccessor();
> + return SI->getDefaultDest();
> + }
> +
> + return nullptr;
> +}
> +
> +/// Helper class that can turn branches and switches with constant conditions
> +/// into unconditional branches.
> +class ConstantTerminatorFoldingImpl {
> +private:
> + Loop &L;
> + LoopInfo &LI;
> + DominatorTree &DT;
> +
> + // Whether or not the current loop will still exist after terminator constant
> + // folding will be done. In theory, there are two ways how it can happen:
> + // 1. Loop's latch(es) become unreachable from loop header;
> + // 2. Loop's header becomes unreachable from method entry.
> + // In practice, the second situation is impossible because we only modify the
> + // current loop and its preheader and do not affect preheader's reachibility
> + // from any other block. So this variable set to true means that loop's latch
> + // has become unreachable from loop header.
> + bool DeleteCurrentLoop = false;
> +
> + // The blocks of the original loop that will still be reachable from entry
> + // after the constant folding.
> + SmallPtrSet<BasicBlock *, 8> LiveLoopBlocks;
> + // The blocks of the original loop that will become unreachable from entry
> + // after the constant folding.
> + SmallPtrSet<BasicBlock *, 8> DeadLoopBlocks;
> + // The exits of the original loop that will still be reachable from entry
> + // after the constant folding.
> + SmallPtrSet<BasicBlock *, 8> LiveExitBlocks;
> + // The exits of the original loop that will become unreachable from entry
> + // after the constant folding.
> + SmallPtrSet<BasicBlock *, 8> DeadExitBlocks;
> + // The blocks that will still be a part of the current loop after folding.
> + SmallPtrSet<BasicBlock *, 8> BlocksInLoopAfterFolding;
> + // The blocks that have terminators with constant condition that can be
> + // folded. Note: fold candidates should be in L but not in any of its
> + // subloops to avoid complex LI updates.
> + SmallVector<BasicBlock *, 8> FoldCandidates;
> +
> + void dump() const {
> + dbgs() << "Constant terminator folding for loop " << L << "\n";
> + dbgs() << "After terminator constant-folding, the loop will";
> + if (!DeleteCurrentLoop)
> + dbgs() << " not";
> + dbgs() << " be destroyed\n";
> + dbgs() << "Blocks in which we can constant-fold terminator:\n";
> + for (const BasicBlock *BB : FoldCandidates)
> + dbgs() << "\t" << BB->getName() << "\n";
> + auto PrintOutSet = [&](const char *Message,
> + const SmallPtrSetImpl<BasicBlock *> &S) {
> + dbgs() << Message << "\n";
> + for (const BasicBlock *BB : S)
> + dbgs() << "\t" << BB->getName() << "\n";
> + };
> + PrintOutSet("Live blocks from the original loop:", LiveLoopBlocks);
> + PrintOutSet("Dead blocks from the original loop:", DeadLoopBlocks);
> + PrintOutSet("Live exit blocks:", LiveExitBlocks);
> + PrintOutSet("Dead exit blocks:", DeadExitBlocks);
> + if (!DeleteCurrentLoop)
> + PrintOutSet("The following blocks will still be part of the loop:",
> + BlocksInLoopAfterFolding);
> + }
> +
> + /// Fill all information about status of blocks and exits of the current loop
> + /// if constant folding of all branches will be done.
> + void analyze() {
> + LoopBlocksDFS DFS(&L);
> + DFS.perform(&LI);
> + assert(DFS.isComplete() && "DFS is expected to be finished");
> +
> + // Collect live and dead loop blocks and exits.
> + SmallPtrSet<BasicBlock *, 8> ExitBlocks;
> + LiveLoopBlocks.insert(L.getHeader());
> + for (auto I = DFS.beginRPO(), E = DFS.endRPO(); I != E; ++I) {
> + BasicBlock *BB = *I;
> +
> + // If a loop block wasn't marked as live so far, then it's dead.
> + if (!LiveLoopBlocks.count(BB)) {
> + DeadLoopBlocks.insert(BB);
> + continue;
> + }
> +
> + BasicBlock *TheOnlySucc = getOnlyLiveSuccessor(BB);
> +
> + // If a block has only one live successor, it's a candidate on constant
> + // folding. Only handle blocks from current loop: branches in child loops
> + // are skipped because if they can be folded, they should be folded during
> + // the processing of child loops.
> + if (TheOnlySucc && LI.getLoopFor(BB) == &L)
> + FoldCandidates.push_back(BB);
> +
> + // Handle successors.
> + auto ProcessSuccessor = [&](BasicBlock *Succ, bool IsLive) {
> + if (!L.contains(Succ)) {
> + if (IsLive)
> + LiveExitBlocks.insert(Succ);
> + ExitBlocks.insert(Succ);
> + } else if (IsLive)
> + LiveLoopBlocks.insert(Succ);
> + };
> + for (BasicBlock *Succ : successors(BB))
> + ProcessSuccessor(Succ, !TheOnlySucc || TheOnlySucc == Succ);
> + }
> +
> + // Sanity check: amount of dead and live loop blocks should match the total
> + // number of blocks in loop.
> + assert(L.getNumBlocks() == LiveLoopBlocks.size() + DeadLoopBlocks.size() &&
> + "Malformed block sets?");
> +
> + // Now, all exit blocks that are not marked as live are dead.
> + for (auto *ExitBlock : ExitBlocks)
> + if (!LiveExitBlocks.count(ExitBlock))
> + DeadExitBlocks.insert(ExitBlock);
> +
> + // Whether or not the edge From->To will still be present in graph after the
> + // folding.
> + auto IsEdgeLive = [&](BasicBlock *From, BasicBlock *To) {
> + if (!LiveLoopBlocks.count(From))
> + return false;
> + BasicBlock *TheOnlySucc = getOnlyLiveSuccessor(From);
> + return !TheOnlySucc || TheOnlySucc == To;
> + };
> +
> + // The loop will not be destroyed if its latch is live.
> + DeleteCurrentLoop = !IsEdgeLive(L.getLoopLatch(), L.getHeader());
> +
> + // If we are going to delete the current loop completely, no extra analysis
> + // is needed.
> + if (DeleteCurrentLoop)
> + return;
> +
> + // Otherwise, we should check which blocks will still be a part of the
> + // current loop after the transform.
> + BlocksInLoopAfterFolding.insert(L.getLoopLatch());
> + // If the loop is live, then we should compute what blocks are still in
> + // loop after all branch folding has been done. A block is in loop if
> + // it has a live edge to another block that is in the loop; by definition,
> + // latch is in the loop.
> + auto BlockIsInLoop = [&](BasicBlock *BB) {
> + return any_of(successors(BB), [&](BasicBlock *Succ) {
> + return BlocksInLoopAfterFolding.count(Succ) && IsEdgeLive(BB, Succ);
> + });
> + };
> + for (auto I = DFS.beginPostorder(), E = DFS.endPostorder(); I != E; ++I) {
> + BasicBlock *BB = *I;
> + if (BlockIsInLoop(BB))
> + BlocksInLoopAfterFolding.insert(BB);
> + }
> +
> + // Sanity check: header must be in loop.
> + assert(BlocksInLoopAfterFolding.count(L.getHeader()) &&
> + "Header not in loop?");
> + }
> +
> + /// Constant-fold terminators of blocks acculumated in FoldCandidates into the
> + /// unconditional branches.
> + void foldTerminators() {
> + DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
> +
> + for (BasicBlock *BB : FoldCandidates) {
> + assert(LI.getLoopFor(BB) == &L && "Should be a loop block!");
> + BasicBlock *TheOnlySucc = getOnlyLiveSuccessor(BB);
> + assert(TheOnlySucc && "Should have one live successor!");
> +
> + LLVM_DEBUG(dbgs() << "Replacing terminator of " << BB->getName()
> + << " with an unconditional branch to the block "
> + << TheOnlySucc->getName() << "\n");
> +
> + SmallPtrSet<BasicBlock *, 2> DeadSuccessors;
> + // Remove all BB's successors except for the live one.
> + for (auto *Succ : successors(BB))
> + if (Succ != TheOnlySucc) {
> + DeadSuccessors.insert(Succ);
> + Succ->removePredecessor(BB);
> + }
> +
> + IRBuilder<> Builder(BB->getContext());
> + Instruction *Term = BB->getTerminator();
> + Builder.SetInsertPoint(Term);
> + Builder.CreateBr(TheOnlySucc);
> + Term->eraseFromParent();
> +
> + for (auto *DeadSucc : DeadSuccessors)
> + DTU.deleteEdge(BB, DeadSucc);
> +
> + ++NumTerminatorsFolded;
> + }
> + }
> +
> +public:
> + ConstantTerminatorFoldingImpl(Loop &L, LoopInfo &LI, DominatorTree &DT)
> + : L(L), LI(LI), DT(DT) {}
> + bool run() {
> + assert(L.getLoopLatch() && "Should be single latch!");
> +
> + // Collect all available information about status of blocks after constant
> + // folding.
> + analyze();
> +
> + LLVM_DEBUG(dbgs() << "In function " << L.getHeader()->getParent()->getName()
> + << ": ");
> +
> + // Nothing to constant-fold.
> + if (FoldCandidates.empty()) {
> + LLVM_DEBUG(
> + dbgs() << "No constant terminator folding candidates found in loop "
> + << L.getHeader()->getName() << "\n");
> + return false;
> + }
> +
> + // TODO: Support deletion of the current loop.
> + if (DeleteCurrentLoop) {
> + LLVM_DEBUG(
> + dbgs()
> + << "Give up constant terminator folding in loop "
> + << L.getHeader()->getName()
> + << ": we don't currently support deletion of the current loop.\n");
> + return false;
> + }
> +
> + // TODO: Support deletion of dead loop blocks.
> + if (!DeadLoopBlocks.empty()) {
> + LLVM_DEBUG(dbgs() << "Give up constant terminator folding in loop "
> + << L.getHeader()->getName()
> + << ": we don't currently"
> + " support deletion of dead in-loop blocks.\n");
> + return false;
> + }
> +
> + // TODO: Support dead loop exits.
> + if (!DeadExitBlocks.empty()) {
> + LLVM_DEBUG(dbgs() << "Give up constant terminator folding in loop "
> + << L.getHeader()->getName()
> + << ": we don't currently support dead loop exits.\n");
> + return false;
> + }
> +
> + // TODO: Support blocks that are not dead, but also not in loop after the
> + // folding.
> + if (BlocksInLoopAfterFolding.size() != L.getNumBlocks()) {
> + LLVM_DEBUG(
> + dbgs() << "Give up constant terminator folding in loop "
> + << L.getHeader()->getName()
> + << ": we don't currently"
> + " support blocks that are not dead, but will stop "
> + "being a part of the loop after constant-folding.\n");
> + return false;
> + }
> +
> + // Dump analysis results.
> + LLVM_DEBUG(dump());
> +
> + LLVM_DEBUG(dbgs() << "Constant-folding " << FoldCandidates.size()
> + << " terminators in loop " << L.getHeader()->getName()
> + << "\n");
> +
> + // Make the actual transforms.
> + foldTerminators();
> +
> +#ifndef NDEBUG
> + // Make sure that we have preserved all data structures after the transform.
> + DT.verify();
> + assert(DT.isReachableFromEntry(L.getHeader()));
> + LI.verify(DT);
> +#endif
> +
> + return true;
> + }
> +};
> +
> +/// Turn branches and switches with known constant conditions into unconditional
> +/// branches.
> +static bool constantFoldTerminators(Loop &L, DominatorTree &DT, LoopInfo &LI) {
> + // To keep things simple, only process loops with single latch. We
> + // canonicalize most loops to this form. We can support multi-latch if needed.
> + if (!L.getLoopLatch())
> + return false;
> +
> + ConstantTerminatorFoldingImpl BranchFolder(L, LI, DT);
> + return BranchFolder.run();
> +}
> +
> static bool mergeBlocksIntoPredecessors(Loop &L, DominatorTree &DT,
> LoopInfo &LI, MemorySSAUpdater *MSSAU) {
> bool Changed = false;
> @@ -73,6 +385,9 @@ static bool simplifyLoopCFG(Loop &L, Dom
> ScalarEvolution &SE, MemorySSAUpdater *MSSAU) {
> bool Changed = false;
>
> + // Constant-fold terminators with known constant conditions.
> + Changed |= constantFoldTerminators(L, DT, LI);
> +
> // Eliminate unconditional branches by merging blocks into their predecessors.
> Changed |= mergeBlocksIntoPredecessors(L, DT, LI, MSSAU);
>
>
> Modified: llvm/trunk/test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll?rev=347289&r1=347288&r2=347289&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll (original)
> +++ llvm/trunk/test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll Mon Nov 19 21:43:32 2018
> @@ -1,10 +1,58 @@
> ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
> -; RUN: opt -S -loop-simplifycfg < %s | FileCheck %s
> -; RUN: opt -S -passes='require<domtree>,loop(simplify-cfg)' < %s | FileCheck %s
> -; RUN: opt -S -loop-simplifycfg -enable-mssa-loop-dependency=true -verify-memoryssa < %s | FileCheck %s
> +; REQUIRES: asserts
> +; RUN: opt -S -loop-simplifycfg -debug-only=loop-simplifycfg 2>&1 < %s | FileCheck %s
> +; RUN: opt -S -passes='require<domtree>,loop(simplify-cfg)' -debug-only=loop-simplifycfg 2>&1 < %s | FileCheck %s
> +; RUN: opt -S -loop-simplifycfg -enable-mssa-loop-dependency=true -verify-memoryssa -debug-only=loop-simplifycfg 2>&1 < %s | FileCheck %s
>
> target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128-ni:1"
>
> +; CHECK-LABEL: In function dead_backedge_test_branch_loop: Give up constant terminator folding in loop header: we don't currently support blocks that are not dead, but will stop being a part of the loop after constant-folding.
> +; CHECK-LABEL: In function dead_backedge_test_switch_loop: Give up constant terminator folding in loop header: we don't currently support blocks that are not dead, but will stop being a part of the loop after constant-folding.
> +; CHECK-LABEL: In function dead_block_test_branch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of dead in-loop blocks.
> +; CHECK-LABEL: In function dead_block_test_switch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of dead in-loop blocks.
> +; CHECK-LABEL: In function dead_block_propogate_test_branch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of dead in-loop blocks.
> +; CHECK-LABEL: In function dead_block_propogate_test_switch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of dead in-loop blocks.
> +; CHECK-LABEL: In function dead_exit_test_branch_loop: Give up constant terminator folding in loop header: we don't currently support dead loop exits.
> +; CHECK-LABEL: In function dead_exit_test_switch_loop: Give up constant terminator folding in loop header: we don't currently support dead loop exits.
> +; CHECK-LABEL: In function dead_loop_test_branch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of the current loop.
> +; CHECK-LABEL: In function dead_loop_test_switch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of the current loop.
> +; CHECK-LABEL: In function dead_sub_loop_test_branch_loop: No constant terminator folding candidates found in loop dead_loop
> +; CHECK-LABEL: In function dead_sub_loop_test_branch_loop: No constant terminator folding candidates found in loop live_loop
> +; CHECK-LABEL: In function dead_sub_loop_test_branch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of dead in-loop blocks.
> +; CHECK-LABEL: In function dead_sub_loop_test_switch_loop: No constant terminator folding candidates found in loop live_loop
> +; CHECK-LABEL: In function dead_sub_loop_test_switch_loop: No constant terminator folding candidates found in loop dead_loop
> +; CHECK-LABEL: In function dead_sub_loop_test_switch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of dead in-loop blocks.
> +; CHECK-LABEL: In function inf_loop_test_branch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of dead in-loop blocks.
> +; CHECK-LABEL: In function inf_loop_test_switch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of dead in-loop blocks.
> +; CHECK-LABEL: In function live_block_test_branch_loop: Constant terminator folding for loop Loop at depth 1 containing: %header<header>,%check,%live,%backedge<latch><exiting>
> +; CHECK: Replacing terminator of check with an unconditional branch to the block backedge
> +; CHECK-LABEL: In function live_block_test_branch_loop_phis: Constant terminator folding for loop Loop at depth 1 containing: %header<header>,%check,%live,%backedge<latch><exiting>
> +; CHECK: Replacing terminator of check with an unconditional branch to the block backedge
> +; CHECK-LABEL: In function live_block_test_switch_loop: Constant terminator folding for loop Loop at depth 1 containing: %header<header>,%check,%live,%backedge<latch><exiting>
> +; CHECK: Replacing terminator of check with an unconditional branch to the block backedge
> +; CHECK-LABEL: In function live_block_test_switch_loop_phis: Constant terminator folding for loop Loop at depth 1 containing: %header<header>,%check,%live,%backedge<latch><exiting>
> +; CHECK: Replacing terminator of check with an unconditional branch to the block backedge
> +; CHECK-LABEL: In function partial_sub_loop_test_branch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of dead in-loop blocks.
> +; CHECK-LABEL: In function partial_sub_loop_test_branch_loop: No constant terminator folding candidates found in loop outer_header
> +; CHECK-LABEL: In function partial_sub_loop_test_switch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of dead in-loop blocks.
> +; CHECK-LABEL: In function partial_sub_loop_test_switch_loop: No constant terminator folding candidates found in loop outer_header
> +; CHECK-LABEL: In function full_sub_loop_test_branch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of the current loop.
> +; CHECK-LABEL: In function full_sub_loop_test_branch_loop: No constant terminator folding candidates found in loop outer_header
> +; CHECK-LABEL: In function full_sub_loop_test_switch_loop: Give up constant terminator folding in loop header: we don't currently support deletion of the current loop.
> +; CHECK-LABEL: In function full_sub_loop_test_switch_loop: No constant terminator folding candidates found in loop outer_header
> +; CHECK-LABEL: In function full_sub_loop_test_branch_loop_inverse_1: Give up constant terminator folding in loop header: we don't currently support deletion of the current loop.
> +; CHECK-LABEL: In function full_sub_loop_test_branch_loop_inverse_1: No constant terminator folding candidates found in loop outer_header
> +; CHECK-LABEL: In function full_sub_loop_test_switch_loop_inverse_1: Give up constant terminator folding in loop header: we don't currently support deletion of the current loop.
> +; CHECK-LABEL: In function full_sub_loop_test_switch_loop_inverse_1: No constant terminator folding candidates found in loop outer_header
> +; CHECK-LABEL: In function full_sub_loop_test_branch_loop_inverse_2: Give up constant terminator folding in loop header: we don't currently support dead loop exits.
> +; CHECK-LABEL: In function full_sub_loop_test_branch_loop_inverse_2: No constant terminator folding candidates found in loop outer_header
> +; CHECK-LABEL: In function full_sub_loop_test_switch_loop_inverse_2: Give up constant terminator folding in loop header: we don't currently support dead loop exits.
> +; CHECK-LABEL: In function full_sub_loop_test_switch_loop_inverse_2: No constant terminator folding candidates found in loop outer_header
> +; CHECK-LABEL: In function full_sub_loop_test_branch_loop_inverse_3: Give up constant terminator folding in loop header: we don't currently support deletion of dead in-loop blocks.
> +; CHECK-LABEL: In function full_sub_loop_test_branch_loop_inverse_3: No constant terminator folding candidates found in loop outer_header
> +; CHECK-LABEL: In function full_sub_loop_test_switch_loop_inverse_3: Give up constant terminator folding in loop header: we don't currently support deletion of dead in-loop blocks.
> +; CHECK-LABEL: In function full_sub_loop_test_switch_loop_inverse_3: No constant terminator folding candidates found in loop outer_header
> +
> ; Make sure that we can eliminate a provably dead backedge.
> define i32 @dead_backedge_test_branch_loop(i32 %end) {
> ; CHECK-LABEL: @dead_backedge_test_branch_loop(
> @@ -707,7 +755,7 @@ define i32 @live_block_test_branch_loop(
> ; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
> ; CHECK-NEXT: br i1 [[C:%.*]], label [[CHECK:%.*]], label [[LIVE:%.*]]
> ; CHECK: check:
> -; CHECK-NEXT: br i1 true, label [[BACKEDGE]], label [[LIVE]]
> +; CHECK-NEXT: br label [[BACKEDGE]]
> ; CHECK: live:
> ; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
> ; CHECK-NEXT: br label [[BACKEDGE]]
> @@ -744,6 +792,54 @@ exit:
> ret i32 %i.inc
> }
>
> +; Check that when the block is not actually dead, we don't remove it. Version
> +; with Phi node.
> +define i32 @live_block_test_branch_loop_phis(i1 %c, i32 %end) {
> +; CHECK-LABEL: @live_block_test_branch_loop_phis(
> +; CHECK-NEXT: preheader:
> +; CHECK-NEXT: br label [[HEADER:%.*]]
> +; CHECK: header:
> +; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
> +; CHECK-NEXT: br i1 [[C:%.*]], label [[CHECK:%.*]], label [[LIVE:%.*]]
> +; CHECK: check:
> +; CHECK-NEXT: br label [[BACKEDGE]]
> +; CHECK: live:
> +; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
> +; CHECK-NEXT: br label [[BACKEDGE]]
> +; CHECK: backedge:
> +; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[I]], [[CHECK]] ], [ [[I_2]], [[LIVE]] ]
> +; CHECK-NEXT: [[I_INC]] = add i32 [[I_1]], 1
> +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[I_INC]], [[END:%.*]]
> +; CHECK-NEXT: br i1 [[CMP]], label [[HEADER]], label [[EXIT:%.*]]
> +; CHECK: exit:
> +; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[BACKEDGE]] ]
> +; CHECK-NEXT: ret i32 [[I_INC_LCSSA]]
> +;
> +preheader:
> + br label %header
> +
> +header:
> + %i = phi i32 [0, %preheader], [%i.inc, %backedge]
> + br i1 %c, label %check, label %live
> +
> +check:
> + br i1 true, label %backedge, label %live
> +
> +live:
> + %phi = phi i32 [ 1, %header ], [ -1, %check ]
> + %i.2 = add i32 %i, %phi
> + br label %backedge
> +
> +backedge:
> + %i.1 = phi i32 [%i, %check], [%i.2, %live]
> + %i.inc = add i32 %i.1, 1
> + %cmp = icmp slt i32 %i.inc, %end
> + br i1 %cmp, label %header, label %exit
> +
> +exit:
> + ret i32 %i.inc
> +}
> +
> define i32 @live_block_test_switch_loop(i1 %c, i32 %end) {
> ; CHECK-LABEL: @live_block_test_switch_loop(
> ; CHECK-NEXT: preheader:
> @@ -752,11 +848,7 @@ define i32 @live_block_test_switch_loop(
> ; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
> ; CHECK-NEXT: br i1 [[C:%.*]], label [[CHECK:%.*]], label [[LIVE:%.*]]
> ; CHECK: check:
> -; CHECK-NEXT: switch i32 1, label [[LIVE]] [
> -; CHECK-NEXT: i32 0, label [[LIVE]]
> -; CHECK-NEXT: i32 1, label [[BACKEDGE]]
> -; CHECK-NEXT: i32 2, label [[LIVE]]
> -; CHECK-NEXT: ]
> +; CHECK-NEXT: br label [[BACKEDGE]]
> ; CHECK: live:
> ; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
> ; CHECK-NEXT: br label [[BACKEDGE]]
> @@ -786,6 +878,54 @@ live:
> br label %backedge
>
> backedge:
> + %i.1 = phi i32 [%i, %check], [%i.2, %live]
> + %i.inc = add i32 %i.1, 1
> + %cmp = icmp slt i32 %i.inc, %end
> + br i1 %cmp, label %header, label %exit
> +
> +exit:
> + ret i32 %i.inc
> +}
> +
> +define i32 @live_block_test_switch_loop_phis(i1 %c, i32 %end) {
> +; CHECK-LABEL: @live_block_test_switch_loop_phis(
> +; CHECK-NEXT: preheader:
> +; CHECK-NEXT: br label [[HEADER:%.*]]
> +; CHECK: header:
> +; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
> +; CHECK-NEXT: br i1 [[C:%.*]], label [[CHECK:%.*]], label [[LIVE:%.*]]
> +; CHECK: check:
> +; CHECK-NEXT: br label [[BACKEDGE]]
> +; CHECK: live:
> +; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
> +; CHECK-NEXT: br label [[BACKEDGE]]
> +; CHECK: backedge:
> +; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[I]], [[CHECK]] ], [ [[I_2]], [[LIVE]] ]
> +; CHECK-NEXT: [[I_INC]] = add i32 [[I_1]], 1
> +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[I_INC]], [[END:%.*]]
> +; CHECK-NEXT: br i1 [[CMP]], label [[HEADER]], label [[EXIT:%.*]]
> +; CHECK: exit:
> +; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[BACKEDGE]] ]
> +; CHECK-NEXT: ret i32 [[I_INC_LCSSA]]
> +;
> +preheader:
> + br label %header
> +
> +header:
> + %i = phi i32 [0, %preheader], [%i.inc, %backedge]
> + br i1 %c, label %check, label %live
> +
> +check:
> + switch i32 1, label %live [i32 0, label %live
> + i32 1, label %backedge
> + i32 2, label %live]
> +
> +live:
> + %phi = phi i32 [ 1, %header ], [ -1, %check ], [ -1, %check ], [ -1, %check ]
> + %i.2 = add i32 %i, %phi
> + br label %backedge
> +
> +backedge:
> %i.1 = phi i32 [%i, %check], [%i.2, %live]
> %i.inc = add i32 %i.1, 1
> %cmp = icmp slt i32 %i.inc, %end
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: bbi-21357.ll
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20181123/55405290/attachment-0001.ksh>
More information about the llvm-commits
mailing list