After llvm commit 8ba2adcf9e54b34ba8efa73ac0d81a1192e4f614 Author: Jun Ma JunMa@linux.alibaba.com

Recommit "Revert "[CVP] processSwitch: Remove default case when switch cover all possible values.""

the following benchmarks grew in size by more than 1%: - 401.bzip2 grew in size by 4% from 36214 to 37510 bytes - [.] BZ2_decompress grew in size by 19%,401.bzip2,[.] BZ2_decompress grew in size by 19% from 7260 to 8660 bytes

Results regressed to # reset_artifacts: -10 # build_abe binutils: -9 # build_abe stage1 -- --set gcc_override_configure=--with-mode=thumb --set gcc_override_configure=--disable-libsanitizer: -8 # build_abe linux: -7 # build_abe glibc: -6 # build_abe stage2 -- --set gcc_override_configure=--with-mode=thumb --set gcc_override_configure=--disable-libsanitizer: -5 # build_llvm true: -3 # true: 0 # benchmark -- -Oz_mthumb artifacts/build-8ba2adcf9e54b34ba8efa73ac0d81a1192e4f614/results_id: 1

from # reset_artifacts: -10 # build_abe binutils: -9 # build_abe stage1 -- --set gcc_override_configure=--with-mode=thumb --set gcc_override_configure=--disable-libsanitizer: -8 # build_abe linux: -7 # build_abe glibc: -6 # build_abe stage2 -- --set gcc_override_configure=--with-mode=thumb --set gcc_override_configure=--disable-libsanitizer: -5 # build_llvm true: -3 # true: 0 # benchmark -- -Oz_mthumb artifacts/build-baseline/results_id: 1

THIS IS THE END OF INTERESTING STUFF. BELOW ARE LINKS TO BUILDS, REPRODUCTION INSTRUCTIONS, AND THE RAW COMMIT.

This commit has regressed these CI configurations: - tcwg_bmk_llvm_apm/llvm-master-arm-spec2k6-Oz

First_bad build: https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_apm-llvm-master-a... Last_good build: https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_apm-llvm-master-a... Baseline build: https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_apm-llvm-master-a... Even more details: https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_apm-llvm-master-a...

Reproduce builds: <cut> mkdir investigate-llvm-8ba2adcf9e54b34ba8efa73ac0d81a1192e4f614 cd investigate-llvm-8ba2adcf9e54b34ba8efa73ac0d81a1192e4f614

# Fetch scripts git clone https://git.linaro.org/toolchain/jenkins-scripts

# Fetch manifests and test.sh script mkdir -p artifacts/manifests curl -o artifacts/manifests/build-baseline.sh https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_apm-llvm-master-a... --fail curl -o artifacts/manifests/build-parameters.sh https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_apm-llvm-master-a... --fail curl -o artifacts/test.sh https://ci.linaro.org/job/tcwg_bmk_ci_llvm-bisect-tcwg_bmk_apm-llvm-master-a... --fail chmod +x artifacts/test.sh

# Reproduce the baseline build (build all pre-requisites) ./jenkins-scripts/tcwg_bmk-build.sh @@ artifacts/manifests/build-baseline.sh

# Save baseline build state (which is then restored in artifacts/test.sh) mkdir -p ./bisect rsync -a --del --delete-excluded --exclude /bisect/ --exclude /artifacts/ --exclude /llvm/ ./ ./bisect/baseline/

cd llvm

# Reproduce first_bad build git checkout --detach 8ba2adcf9e54b34ba8efa73ac0d81a1192e4f614 ../artifacts/test.sh

# Reproduce last_good build git checkout --detach d1280f6967db1ca8fa4e0c39414003e717b40feb ../artifacts/test.sh

cd .. </cut>

Full commit (up to 1000 lines): <cut> commit 8ba2adcf9e54b34ba8efa73ac0d81a1192e4f614 Author: Jun Ma JunMa@linux.alibaba.com Date: Fri Aug 20 17:27:00 2021 +0800

Recommit "Revert "[CVP] processSwitch: Remove default case when switch cover all possible values.""

Differential Revision: https://reviews.llvm.org/D106056 --- llvm/include/llvm/Transforms/Utils/Local.h | 5 ++++ .../Scalar/CorrelatedValuePropagation.cpp | 27 +++++++++++++++++++++- llvm/lib/Transforms/Utils/Local.cpp | 20 ++++++++++++++++ llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 20 ---------------- .../Transforms/CorrelatedValuePropagation/basic.ll | 11 +++++---- 5 files changed, 57 insertions(+), 26 deletions(-)

diff --git a/llvm/include/llvm/Transforms/Utils/Local.h b/llvm/include/llvm/Transforms/Utils/Local.h index 97686d7d5f2f..f003615eca78 100644 --- a/llvm/include/llvm/Transforms/Utils/Local.h +++ b/llvm/include/llvm/Transforms/Utils/Local.h @@ -55,6 +55,7 @@ class MDNode; class MemorySSAUpdater; class PHINode; class StoreInst; +class SwitchInst; class TargetLibraryInfo; class TargetTransformInfo;

@@ -236,6 +237,10 @@ CallInst *createCallMatchingInvoke(InvokeInst *II); /// This function converts the specified invoek into a normall call. void changeToCall(InvokeInst *II, DomTreeUpdater *DTU = nullptr);

+/// This function removes the default destination from the specified switch. +void createUnreachableSwitchDefault(SwitchInst *Switch, + DomTreeUpdater *DTU = nullptr); + ///===---------------------------------------------------------------------===// /// Dbg Intrinsic utilities /// diff --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp index 36cbd42a5fdd..cd38ce96e287 100644 --- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp +++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp @@ -341,7 +341,13 @@ static bool processSwitch(SwitchInst *I, LazyValueInfo *LVI, // ConstantFoldTerminator() as the underlying SwitchInst can be changed. SwitchInstProfUpdateWrapper SI(*I);

- for (auto CI = SI->case_begin(), CE = SI->case_end(); CI != CE;) { + APInt Low = + APInt::getSignedMaxValue(Cond->getType()->getScalarSizeInBits()); + APInt High = + APInt::getSignedMinValue(Cond->getType()->getScalarSizeInBits()); + + SwitchInst::CaseIt CI = SI->case_begin(); + for (auto CE = SI->case_end(); CI != CE;) { ConstantInt *Case = CI->getCaseValue(); LazyValueInfo::Tristate State = LVI->getPredicateAt(CmpInst::ICMP_EQ, Cond, Case, I, @@ -374,9 +380,28 @@ static bool processSwitch(SwitchInst *I, LazyValueInfo *LVI, break; }

+ // Get Lower/Upper bound from switch cases. + Low = APIntOps::smin(Case->getValue(), Low); + High = APIntOps::smax(Case->getValue(), High); + // Increment the case iterator since we didn't delete it. ++CI; } + + // Try to simplify default case as unreachable + if (CI == SI->case_end() && SI->getNumCases() != 0 && + !isa<UnreachableInst>(SI->getDefaultDest()->getFirstNonPHIOrDbg())) { + const ConstantRange SIRange = + LVI->getConstantRange(SI->getCondition(), SI); + + // If the numbered switch cases cover the entire range of the condition, + // then the default case is not reachable. + if (SIRange.getSignedMin() == Low && SIRange.getSignedMax() == High && + SI->getNumCases() == High - Low + 1) { + createUnreachableSwitchDefault(SI, &DTU); + Changed = true; + } + } }

if (Changed) diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp index 3d6ffded9b19..6d7eca8e3678 100644 --- a/llvm/lib/Transforms/Utils/Local.cpp +++ b/llvm/lib/Transforms/Utils/Local.cpp @@ -2182,6 +2182,26 @@ void llvm::changeToCall(InvokeInst *II, DomTreeUpdater *DTU) { DTU->applyUpdates({{DominatorTree::Delete, BB, UnwindDestBB}}); }

+void llvm::createUnreachableSwitchDefault(SwitchInst *Switch, + DomTreeUpdater *DTU) { + LLVM_DEBUG(dbgs() << "SimplifyCFG: switch default is dead.\n"); + auto *BB = Switch->getParent(); + auto *OrigDefaultBlock = Switch->getDefaultDest(); + OrigDefaultBlock->removePredecessor(BB); + BasicBlock *NewDefaultBlock = BasicBlock::Create( + BB->getContext(), BB->getName() + ".unreachabledefault", BB->getParent(), + OrigDefaultBlock); + new UnreachableInst(Switch->getContext(), NewDefaultBlock); + Switch->setDefaultDest(&*NewDefaultBlock); + if (DTU) { + SmallVector<DominatorTree::UpdateType, 2> Updates; + Updates.push_back({DominatorTree::Insert, BB, &*NewDefaultBlock}); + if (!is_contained(successors(BB), OrigDefaultBlock)) + Updates.push_back({DominatorTree::Delete, BB, &*OrigDefaultBlock}); + DTU->applyUpdates(Updates); + } +} + BasicBlock *llvm::changeToInvokeAndSplitBasicBlock(CallInst *CI, BasicBlock *UnwindEdge, DomTreeUpdater *DTU) { diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index 737b4f97a97a..70297e471a7a 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -4743,26 +4743,6 @@ static bool CasesAreContiguous(SmallVectorImpl<ConstantInt *> &Cases) { return true; }

-static void createUnreachableSwitchDefault(SwitchInst *Switch, - DomTreeUpdater *DTU) { - LLVM_DEBUG(dbgs() << "SimplifyCFG: switch default is dead.\n"); - auto *BB = Switch->getParent(); - auto *OrigDefaultBlock = Switch->getDefaultDest(); - OrigDefaultBlock->removePredecessor(BB); - BasicBlock *NewDefaultBlock = BasicBlock::Create( - BB->getContext(), BB->getName() + ".unreachabledefault", BB->getParent(), - OrigDefaultBlock); - new UnreachableInst(Switch->getContext(), NewDefaultBlock); - Switch->setDefaultDest(&*NewDefaultBlock); - if (DTU) { - SmallVector<DominatorTree::UpdateType, 2> Updates; - Updates.push_back({DominatorTree::Insert, BB, &*NewDefaultBlock}); - if (!is_contained(successors(BB), OrigDefaultBlock)) - Updates.push_back({DominatorTree::Delete, BB, &*OrigDefaultBlock}); - DTU->applyUpdates(Updates); - } -} - /// Turn a switch with two reachable destinations into an integer range /// comparison and branch. bool SimplifyCFGOpt::TurnSwitchRangeIntoICmp(SwitchInst *SI, diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll b/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll index 5abbcbc90e01..a620c8468d4d 100644 --- a/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll +++ b/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll @@ -382,7 +382,7 @@ define i32 @switch_range(i32 %cond) { ; CHECK-NEXT: entry: ; CHECK-NEXT: [[S:%.*]] = urem i32 [[COND:%.*]], 3 ; CHECK-NEXT: [[S1:%.*]] = add nuw nsw i32 [[S]], 1 -; CHECK-NEXT: switch i32 [[S1]], label [[UNREACHABLE:%.*]] [ +; CHECK-NEXT: switch i32 [[S1]], label [[ENTRY_UNREACHABLEDEFAULT:%.*]] [ ; CHECK-NEXT: i32 1, label [[EXIT1:%.*]] ; CHECK-NEXT: i32 2, label [[EXIT2:%.*]] ; CHECK-NEXT: i32 3, label [[EXIT1]] @@ -391,6 +391,8 @@ define i32 @switch_range(i32 %cond) { ; CHECK-NEXT: ret i32 1 ; CHECK: exit2: ; CHECK-NEXT: ret i32 2 +; CHECK: entry.unreachabledefault: +; CHECK-NEXT: unreachable ; CHECK: unreachable: ; CHECK-NEXT: ret i32 0 ; @@ -453,10 +455,9 @@ define i8 @switch_defaultdest_multipleuse(i8 %t0) { ; CHECK-NEXT: entry: ; CHECK-NEXT: [[O:%.*]] = or i8 [[T0:%.*]], 1 ; CHECK-NEXT: [[R:%.*]] = srem i8 1, [[O]] -; CHECK-NEXT: switch i8 [[R]], label [[EXIT:%.*]] [ -; CHECK-NEXT: i8 0, label [[EXIT]] -; CHECK-NEXT: i8 1, label [[EXIT]] -; CHECK-NEXT: ] +; CHECK-NEXT: br label [[EXIT:%.*]] +; CHECK: entry.unreachabledefault: +; CHECK-NEXT: unreachable ; CHECK: exit: ; CHECK-NEXT: ret i8 0 ; </cut>