[llvm] r355846 - [Utils] Extract EliminateUnreachableBlocks (NFC)
Brian Gesiak via llvm-commits
llvm-commits at lists.llvm.org
Wed Mar 13 08:32:23 PDT 2019
Thanks for the suggestion here. I looked into merging these two functions
and I sent an email about what I found:
http://lists.llvm.org/pipermail/llvm-dev/2019-March/130956.html
- Brian
On Mon, Mar 11, 2019 at 2:08 PM Brian Gesiak <modocache at gmail.com> wrote:
> Oh, I hadn't realized that! Yes, I'll do so today. - Brian
>
> On Mon, Mar 11, 2019 at 1:58 PM Philip Reames <listmail at philipreames.com>
> wrote:
>
>> Unless I'm mistaken, this duplicates removeUnreachableBlocks in
>> Transforms/Utils/Local.h. Can you merge them please?
>>
>> On 3/11/19 10:51 AM, Brian Gesiak via llvm-commits wrote:
>> > Author: modocache
>> > Date: Mon Mar 11 10:51:57 2019
>> > New Revision: 355846
>> >
>> > URL: http://llvm.org/viewvc/llvm-project?rev=355846&view=rev
>> > Log:
>> > [Utils] Extract EliminateUnreachableBlocks (NFC)
>> >
>> > Summary:
>> > Extract the functionality of eliminating unreachable basic blocks
>> > within a function, previously encapsulated within the
>> > -unreachableblockelim pass, and make it available as a function within
>> > BlockUtils.h. No functional change intended other than making the logic
>> > reusable.
>> >
>> > Exposing this logic makes it easier to implement
>> > https://reviews.llvm.org/D59068, which fixes coroutines bug
>> > https://bugs.llvm.org/show_bug.cgi?id=40979.
>> >
>> > Reviewers: mkazantsev, wmi, davidxl, silvas, davide
>> >
>> > Reviewed By: davide
>> >
>> > Subscribers: llvm-commits
>> >
>> > Tags: #llvm
>> >
>> > Differential Revision: https://reviews.llvm.org/D59069
>> >
>> > Modified:
>> > llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
>> > llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp
>> > llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
>> > llvm/trunk/unittests/Transforms/Utils/BasicBlockUtilsTest.cpp
>> >
>> > 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=355846&r1=355845&r2=355846&view=diff
>> >
>> ==============================================================================
>> > --- llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
>> (original)
>> > +++ llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h Mon Mar
>> 11 10:51:57 2019
>> > @@ -62,6 +62,12 @@ void DeleteDeadBlocks(ArrayRef <BasicBlo
>> > DomTreeUpdater *DTU = nullptr,
>> > bool KeepOneInputPHIs = false);
>> >
>> > +/// Delete all basic blocks from \p F that are not reachable from its
>> entry
>> > +/// node. If \p KeepOneInputPHIs is true, one-input Phis in successors
>> of
>> > +/// blocks being deleted will be preserved.
>> > +bool EliminateUnreachableBlocks(Function &F, DomTreeUpdater *DTU =
>> nullptr,
>> > + bool KeepOneInputPHIs = false);
>> > +
>> > /// We know that BB has one predecessor. If there are any single-entry
>> PHI nodes
>> > /// in it, fold them away. This handles the case when all entries to
>> the PHI
>> > /// nodes in a block are guaranteed equal, such as when the block has
>> exactly
>> >
>> > Modified: llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp?rev=355846&r1=355845&r2=355846&view=diff
>> >
>> ==============================================================================
>> > --- llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp (original)
>> > +++ llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp Mon Mar 11 10:51:57
>> 2019
>> > @@ -40,31 +40,10 @@
>> > #include "llvm/Transforms/Utils/BasicBlockUtils.h"
>> > using namespace llvm;
>> >
>> > -static bool eliminateUnreachableBlock(Function &F) {
>> > - df_iterator_default_set<BasicBlock*> Reachable;
>> > -
>> > - // Mark all reachable blocks.
>> > - for (BasicBlock *BB : depth_first_ext(&F, Reachable))
>> > - (void)BB/* Mark all reachable blocks */;
>> > -
>> > - // Collect all dead blocks.
>> > - std::vector<BasicBlock*> DeadBlocks;
>> > - for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
>> > - if (!Reachable.count(&*I)) {
>> > - BasicBlock *BB = &*I;
>> > - DeadBlocks.push_back(BB);
>> > - }
>> > -
>> > - // Delete the dead blocks.
>> > - DeleteDeadBlocks(DeadBlocks);
>> > -
>> > - return !DeadBlocks.empty();
>> > -}
>> > -
>> > namespace {
>> > class UnreachableBlockElimLegacyPass : public FunctionPass {
>> > bool runOnFunction(Function &F) override {
>> > - return eliminateUnreachableBlock(F);
>> > + return llvm::EliminateUnreachableBlocks(F);
>> > }
>> >
>> > public:
>> > @@ -89,7 +68,7 @@ FunctionPass *llvm::createUnreachableBlo
>> >
>> > PreservedAnalyses UnreachableBlockElimPass::run(Function &F,
>> >
>> FunctionAnalysisManager &AM) {
>> > - bool Changed = eliminateUnreachableBlock(F);
>> > + bool Changed = llvm::EliminateUnreachableBlocks(F);
>> > if (!Changed)
>> > return PreservedAnalyses::all();
>> > PreservedAnalyses PA;
>> >
>> > Modified: llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp?rev=355846&r1=355845&r2=355846&view=diff
>> >
>> ==============================================================================
>> > --- llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp (original)
>> > +++ llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp Mon Mar 11
>> 10:51:57 2019
>> > @@ -110,6 +110,28 @@ void llvm::DeleteDeadBlocks(ArrayRef <Ba
>> > BB->eraseFromParent();
>> > }
>> >
>> > +bool llvm::EliminateUnreachableBlocks(Function &F, DomTreeUpdater *DTU,
>> > + bool KeepOneInputPHIs) {
>> > + df_iterator_default_set<BasicBlock*> Reachable;
>> > +
>> > + // Mark all reachable blocks.
>> > + for (BasicBlock *BB : depth_first_ext(&F, Reachable))
>> > + (void)BB/* Mark all reachable blocks */;
>> > +
>> > + // Collect all dead blocks.
>> > + std::vector<BasicBlock*> DeadBlocks;
>> > + for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
>> > + if (!Reachable.count(&*I)) {
>> > + BasicBlock *BB = &*I;
>> > + DeadBlocks.push_back(BB);
>> > + }
>> > +
>> > + // Delete the dead blocks.
>> > + DeleteDeadBlocks(DeadBlocks, DTU, KeepOneInputPHIs);
>> > +
>> > + return !DeadBlocks.empty();
>> > +}
>> > +
>> > void llvm::FoldSingleEntryPHINodes(BasicBlock *BB,
>> > MemoryDependenceResults *MemDep) {
>> > if (!isa<PHINode>(BB->begin())) return;
>> >
>> > Modified: llvm/trunk/unittests/Transforms/Utils/BasicBlockUtilsTest.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Transforms/Utils/BasicBlockUtilsTest.cpp?rev=355846&r1=355845&r2=355846&view=diff
>> >
>> ==============================================================================
>> > --- llvm/trunk/unittests/Transforms/Utils/BasicBlockUtilsTest.cpp
>> (original)
>> > +++ llvm/trunk/unittests/Transforms/Utils/BasicBlockUtilsTest.cpp Mon
>> Mar 11 10:51:57 2019
>> > @@ -25,6 +25,64 @@ static std::unique_ptr<Module> parseIR(L
>> > return Mod;
>> > }
>> >
>> > +TEST(BasicBlockUtils, EliminateUnreachableBlocks) {
>> > + LLVMContext C;
>> > +
>> > + std::unique_ptr<Module> M = parseIR(
>> > + C,
>> > + "define i32 @has_unreachable(i1 %cond) {\n"
>> > + "entry:\n"
>> > + " br i1 %cond, label %bb0, label %bb1\n"
>> > + "bb0:\n"
>> > + " br label %bb1\n"
>> > + "bb1:\n"
>> > + " %phi = phi i32 [ 0, %entry ], [ 1, %bb0 ]"
>> > + " ret i32 %phi\n"
>> > + "bb2:\n"
>> > + " ret i32 42\n"
>> > + "}\n"
>> > + "\n"
>> > + );
>> > +
>> > + auto *F = M->getFunction("has_unreachable");
>> > + DominatorTree DT(*F);
>> > + DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
>> > +
>> > + EXPECT_EQ(F->size(), (size_t)4);
>> > + bool Result = EliminateUnreachableBlocks(*F, &DTU);
>> > + EXPECT_TRUE(Result);
>> > + EXPECT_EQ(F->size(), (size_t)3);
>> > + EXPECT_TRUE(DT.verify());
>> > +}
>> > +
>> > +TEST(BasicBlockUtils, NoUnreachableBlocksToEliminate) {
>> > + LLVMContext C;
>> > +
>> > + std::unique_ptr<Module> M = parseIR(
>> > + C,
>> > + "define i32 @no_unreachable(i1 %cond) {\n"
>> > + "entry:\n"
>> > + " br i1 %cond, label %bb0, label %bb1\n"
>> > + "bb0:\n"
>> > + " br label %bb1\n"
>> > + "bb1:\n"
>> > + " %phi = phi i32 [ 0, %entry ], [ 1, %bb0 ]"
>> > + " ret i32 %phi\n"
>> > + "}\n"
>> > + "\n"
>> > + );
>> > +
>> > + auto *F = M->getFunction("no_unreachable");
>> > + DominatorTree DT(*F);
>> > + DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
>> > +
>> > + EXPECT_EQ(F->size(), (size_t)3);
>> > + bool Result = EliminateUnreachableBlocks(*F, &DTU);
>> > + EXPECT_FALSE(Result);
>> > + EXPECT_EQ(F->size(), (size_t)3);
>> > + EXPECT_TRUE(DT.verify());
>> > +}
>> > +
>> > TEST(BasicBlockUtils, SplitBlockPredecessors) {
>> > LLVMContext C;
>> >
>> >
>> >
>> > _______________________________________________
>> > llvm-commits mailing list
>> > llvm-commits at lists.llvm.org
>> > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>>
>
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