[llvm] 624d34a - [OpenMP] Compute a proper module slice for the CGSCCC pass
Johannes Doerfert via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 10 23:50:13 PDT 2020
Author: Johannes Doerfert
Date: 2020-07-11T01:44:00-05:00
New Revision: 624d34afff5de099a6f84e678c81055556c3d42d
URL: https://github.com/llvm/llvm-project/commit/624d34afff5de099a6f84e678c81055556c3d42d
DIFF: https://github.com/llvm/llvm-project/commit/624d34afff5de099a6f84e678c81055556c3d42d.diff
LOG: [OpenMP] Compute a proper module slice for the CGSCCC pass
The module slice describes which functions we can analyze and transform
while working on an SCC as part of the CGSCC OpenMPOpt pass. So far, we
simply restricted it to the SCC. In a follow up we will need to have a
bigger scope which is why this patch introduces a proper identification
of the module slice. In short, everything that has a transitive
reference to a function in the SCC or is transitively referenced by one
is fair game.
Reviewed By: sstefan1
Differential Revision: https://reviews.llvm.org/D83270
Added:
Modified:
llvm/lib/Transforms/IPO/OpenMPOpt.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/IPO/OpenMPOpt.cpp b/llvm/lib/Transforms/IPO/OpenMPOpt.cpp
index f0fc8a6c8c4a..38647b5eae68 100644
--- a/llvm/lib/Transforms/IPO/OpenMPOpt.cpp
+++ b/llvm/lib/Transforms/IPO/OpenMPOpt.cpp
@@ -57,6 +57,28 @@ STATISTIC(NumOpenMPTargetRegionKernels,
static constexpr auto TAG = "[" DEBUG_TYPE "]";
#endif
+/// Apply \p CB to all uses of \p F. If \p LookThroughConstantExprUses is
+/// true, constant expression users are not given to \p CB but their uses are
+/// traversed transitively.
+template <typename CBTy>
+static void foreachUse(Function &F, CBTy CB,
+ bool LookThroughConstantExprUses = true) {
+ SmallVector<Use *, 8> Worklist(make_pointer_range(F.uses()));
+
+ for (unsigned idx = 0; idx < Worklist.size(); ++idx) {
+ Use &U = *Worklist[idx];
+
+ // Allow use in constant bitcasts and simply look through them.
+ if (LookThroughConstantExprUses && isa<ConstantExpr>(U.getUser())) {
+ for (Use &CEU : cast<ConstantExpr>(U.getUser())->uses())
+ Worklist.push_back(&CEU);
+ continue;
+ }
+
+ CB(U);
+ }
+}
+
/// Helper struct to store tracked ICV values at specif instructions.
struct ICVValue {
Instruction *Inst;
@@ -102,11 +124,12 @@ struct AAICVTracker;
/// Attributor runs.
struct OMPInformationCache : public InformationCache {
OMPInformationCache(Module &M, AnalysisGetter &AG,
- BumpPtrAllocator &Allocator, SetVector<Function *> *CGSCC,
- SmallPtrSetImpl<Function *> &ModuleSlice,
+ BumpPtrAllocator &Allocator, SetVector<Function *> &CGSCC,
SmallPtrSetImpl<Kernel> &Kernels)
- : InformationCache(M, AG, Allocator, CGSCC), ModuleSlice(ModuleSlice),
- OMPBuilder(M), Kernels(Kernels) {
+ : InformationCache(M, AG, Allocator, &CGSCC), OMPBuilder(M),
+ Kernels(Kernels) {
+ initializeModuleSlice(CGSCC);
+
OMPBuilder.initialize();
initializeRuntimeFunctions();
initializeInternalControlVars();
@@ -196,20 +219,20 @@ struct OMPInformationCache : public InformationCache {
/// Run the callback \p CB on each use and forget the use if the result is
/// true. The callback will be fed the function in which the use was
/// encountered as second argument.
- void foreachUse(function_ref<bool(Use &, Function &)> CB) {
- for (auto &It : UsesMap)
- foreachUse(CB, It.first, It.second.get());
+ void foreachUse(SmallVectorImpl<Function *> &SCC,
+ function_ref<bool(Use &, Function &)> CB) {
+ for (Function *F : SCC)
+ foreachUse(CB, F);
}
/// Run the callback \p CB on each use within the function \p F and forget
/// the use if the result is true.
- void foreachUse(function_ref<bool(Use &, Function &)> CB, Function *F,
- UseVector *Uses = nullptr) {
+ void foreachUse(function_ref<bool(Use &, Function &)> CB, Function *F) {
SmallVector<unsigned, 8> ToBeDeleted;
ToBeDeleted.clear();
unsigned Idx = 0;
- UseVector &UV = Uses ? *Uses : getOrCreateUseVector(F);
+ UseVector &UV = getOrCreateUseVector(F);
for (Use *U : UV) {
if (CB(*U, *F))
@@ -232,8 +255,45 @@ struct OMPInformationCache : public InformationCache {
DenseMap<Function *, std::shared_ptr<UseVector>> UsesMap;
};
+ /// Initialize the ModuleSlice member based on \p SCC. ModuleSlices contains
+ /// (a subset of) all functions that we can look at during this SCC traversal.
+ /// This includes functions (transitively) called from the SCC and the
+ /// (transitive) callers of SCC functions. We also can look at a function if
+ /// there is a "reference edge", i.a., if the function somehow uses (!=calls)
+ /// a function in the SCC or a caller of a function in the SCC.
+ void initializeModuleSlice(SetVector<Function *> &SCC) {
+ ModuleSlice.insert(SCC.begin(), SCC.end());
+
+ SmallPtrSet<Function *, 16> Seen;
+ SmallVector<Function *, 16> Worklist(SCC.begin(), SCC.end());
+ while (!Worklist.empty()) {
+ Function *F = Worklist.pop_back_val();
+ ModuleSlice.insert(F);
+
+ for (Instruction &I : instructions(*F))
+ if (auto *CB = dyn_cast<CallBase>(&I))
+ if (Function *Callee = CB->getCalledFunction())
+ if (Seen.insert(Callee).second)
+ Worklist.push_back(Callee);
+ }
+
+ Seen.clear();
+ Worklist.append(SCC.begin(), SCC.end());
+ while (!Worklist.empty()) {
+ Function *F = Worklist.pop_back_val();
+ ModuleSlice.insert(F);
+
+ // Traverse all transitive uses.
+ foreachUse(*F, [&](Use &U) {
+ if (auto *UsrI = dyn_cast<Instruction>(U.getUser()))
+ if (Seen.insert(UsrI->getFunction()).second)
+ Worklist.push_back(UsrI->getFunction());
+ });
+ }
+ }
+
/// The slice of the module we are allowed to look at.
- SmallPtrSetImpl<Function *> &ModuleSlice;
+ SmallPtrSet<Function *, 8> ModuleSlice;
/// An OpenMP-IR-Builder instance
OpenMPIRBuilder OMPBuilder;
@@ -548,7 +608,7 @@ struct OpenMPOpt {
return true;
};
- RFI.foreachUse(DeleteCallCB);
+ RFI.foreachUse(SCC, DeleteCallCB);
return Changed;
}
@@ -633,7 +693,7 @@ struct OpenMPOpt {
/* GlobalOnly */ true, SingleChoice);
return false;
};
- RFI.foreachUse(CombineIdentStruct);
+ RFI.foreachUse(SCC, CombineIdentStruct);
if (!Ident || !SingleChoice) {
// The IRBuilder uses the insertion block to get to the module, this is
@@ -733,7 +793,7 @@ struct OpenMPOpt {
Changed = true;
return true;
};
- RFI.foreachUse(ReplaceAndDeleteCB);
+ RFI.foreachUse(SCC, ReplaceAndDeleteCB);
return Changed;
}
@@ -776,7 +836,7 @@ struct OpenMPOpt {
OMPInformationCache::RuntimeFunctionInfo &GlobThreadNumRFI =
OMPInfoCache.RFIs[OMPRTL___kmpc_global_thread_num];
- GlobThreadNumRFI.foreachUse([&](Use &U, Function &F) {
+ GlobThreadNumRFI.foreachUse(SCC, [&](Use &U, Function &F) {
if (CallInst *CI = getCallIfRegularCall(U, &GlobThreadNumRFI))
AddUserArgs(*CI);
return false;
@@ -938,7 +998,7 @@ struct AAICVTrackerFunction : public AAICVTracker {
return true;
};
- GetterRFI.foreachUse(ReplaceAndDeleteCB);
+ GetterRFI.foreachUse(ReplaceAndDeleteCB, getAnchorScope());
return Changed;
}
@@ -1048,12 +1108,9 @@ PreservedAnalyses OpenMPOptPass::run(LazyCallGraph::SCC &C,
if (DisableOpenMPOptimizations)
return PreservedAnalyses::all();
- SmallPtrSet<Function *, 16> ModuleSlice;
SmallVector<Function *, 16> SCC;
- for (LazyCallGraph::Node &N : C) {
+ for (LazyCallGraph::Node &N : C)
SCC.push_back(&N.getFunction());
- ModuleSlice.insert(SCC.back());
- }
if (SCC.empty())
return PreservedAnalyses::all();
@@ -1073,8 +1130,7 @@ PreservedAnalyses OpenMPOptPass::run(LazyCallGraph::SCC &C,
SetVector<Function *> Functions(SCC.begin(), SCC.end());
BumpPtrAllocator Allocator;
OMPInformationCache InfoCache(*(Functions.back()->getParent()), AG, Allocator,
- /*CGSCC*/ &Functions, ModuleSlice,
- OMPInModule.getKernels());
+ /*CGSCC*/ Functions, OMPInModule.getKernels());
Attributor A(Functions, InfoCache, CGUpdater);
@@ -1112,14 +1168,11 @@ struct OpenMPOptLegacyPass : public CallGraphSCCPass {
if (DisableOpenMPOptimizations || skipSCC(CGSCC))
return false;
- SmallPtrSet<Function *, 16> ModuleSlice;
SmallVector<Function *, 16> SCC;
for (CallGraphNode *CGN : CGSCC)
if (Function *Fn = CGN->getFunction())
- if (!Fn->isDeclaration()) {
+ if (!Fn->isDeclaration())
SCC.push_back(Fn);
- ModuleSlice.insert(Fn);
- }
if (SCC.empty())
return false;
@@ -1141,7 +1194,7 @@ struct OpenMPOptLegacyPass : public CallGraphSCCPass {
BumpPtrAllocator Allocator;
OMPInformationCache InfoCache(
*(Functions.back()->getParent()), AG, Allocator,
- /*CGSCC*/ &Functions, ModuleSlice, OMPInModule.getKernels());
+ /*CGSCC*/ Functions, OMPInModule.getKernels());
Attributor A(Functions, InfoCache, CGUpdater);
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