[llvm] r372874 - [Dominators][AMDGPU] Don't use virtual exit node in findNearestCommonDominator. Cleanup MachinePostDominators.
Jakub Kuderski via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 25 07:04:36 PDT 2019
Author: kuhar
Date: Wed Sep 25 07:04:36 2019
New Revision: 372874
URL: http://llvm.org/viewvc/llvm-project?rev=372874&view=rev
Log:
[Dominators][AMDGPU] Don't use virtual exit node in findNearestCommonDominator. Cleanup MachinePostDominators.
Summary:
This patch fixes a bug that originated from passing a virtual exit block (nullptr) to `MachinePostDominatorTee::findNearestCommonDominator` and resulted in assertion failures inside its callee. It also applies a small cleanup to the class.
The patch introduces a new function in PDT that given a list of `MachineBasicBlock`s finds their NCD. The new overload of `findNearestCommonDominator` handles virtual root correctly.
Note that similar handling of virtual root nodes is not necessary in (forward) `DominatorTree`s, as right now they don't use virtual roots.
Reviewers: tstellar, tpr, nhaehnle, arsenm, NutshellySima, grosser, hliao
Reviewed By: hliao
Subscribers: hliao, kzhuravl, jvesely, wdng, yaxunl, dstuttard, t-tye, hiraditya, llvm-commits
Tags: #amdgpu, #llvm
Differential Revision: https://reviews.llvm.org/D67974
Modified:
llvm/trunk/include/llvm/CodeGen/MachinePostDominators.h
llvm/trunk/include/llvm/CodeGen/MachineRegionInfo.h
llvm/trunk/lib/CodeGen/MachinePostDominators.cpp
llvm/trunk/lib/Target/AMDGPU/SILowerI1Copies.cpp
Modified: llvm/trunk/include/llvm/CodeGen/MachinePostDominators.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachinePostDominators.h?rev=372874&r1=372873&r2=372874&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/MachinePostDominators.h (original)
+++ llvm/trunk/include/llvm/CodeGen/MachinePostDominators.h Wed Sep 25 07:04:36 2019
@@ -16,68 +16,75 @@
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
+#include <memory>
namespace llvm {
///
-/// PostDominatorTree Class - Concrete subclass of DominatorTree that is used
-/// to compute the post-dominator tree.
+/// MachinePostDominatorTree - an analysis pass wrapper for DominatorTree
+/// used to compute the post-dominator tree for MachineFunctions.
///
-struct MachinePostDominatorTree : public MachineFunctionPass {
-private:
- PostDomTreeBase<MachineBasicBlock> *DT;
+class MachinePostDominatorTree : public MachineFunctionPass {
+ using PostDomTreeT = PostDomTreeBase<MachineBasicBlock>;
+ std::unique_ptr<PostDomTreeT> PDT;
public:
static char ID;
MachinePostDominatorTree();
- ~MachinePostDominatorTree() override;
-
FunctionPass *createMachinePostDominatorTreePass();
const SmallVectorImpl<MachineBasicBlock *> &getRoots() const {
- return DT->getRoots();
+ return PDT->getRoots();
}
- MachineDomTreeNode *getRootNode() const {
- return DT->getRootNode();
- }
+ MachineDomTreeNode *getRootNode() const { return PDT->getRootNode(); }
MachineDomTreeNode *operator[](MachineBasicBlock *BB) const {
- return DT->getNode(BB);
+ return PDT->getNode(BB);
}
MachineDomTreeNode *getNode(MachineBasicBlock *BB) const {
- return DT->getNode(BB);
+ return PDT->getNode(BB);
}
bool dominates(const MachineDomTreeNode *A,
const MachineDomTreeNode *B) const {
- return DT->dominates(A, B);
+ return PDT->dominates(A, B);
}
bool dominates(const MachineBasicBlock *A, const MachineBasicBlock *B) const {
- return DT->dominates(A, B);
+ return PDT->dominates(A, B);
}
bool properlyDominates(const MachineDomTreeNode *A,
const MachineDomTreeNode *B) const {
- return DT->properlyDominates(A, B);
+ return PDT->properlyDominates(A, B);
}
bool properlyDominates(const MachineBasicBlock *A,
const MachineBasicBlock *B) const {
- return DT->properlyDominates(A, B);
+ return PDT->properlyDominates(A, B);
+ }
+
+ bool isVirtualRoot(const MachineDomTreeNode *Node) const {
+ return PDT->isVirtualRoot(Node);
}
MachineBasicBlock *findNearestCommonDominator(MachineBasicBlock *A,
- MachineBasicBlock *B) {
- return DT->findNearestCommonDominator(A, B);
+ MachineBasicBlock *B) const {
+ return PDT->findNearestCommonDominator(A, B);
}
+ /// Returns the nearest common dominator of the given blocks.
+ /// If that tree node is a virtual root, a nullptr will be returned.
+ MachineBasicBlock *
+ findNearestCommonDominator(ArrayRef<MachineBasicBlock *> Blocks) const;
+
bool runOnMachineFunction(MachineFunction &MF) override;
void getAnalysisUsage(AnalysisUsage &AU) const override;
+ void releaseMemory() override { PDT.reset(nullptr); }
void print(llvm::raw_ostream &OS, const Module *M = nullptr) const override;
};
} //end of namespace llvm
Modified: llvm/trunk/include/llvm/CodeGen/MachineRegionInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineRegionInfo.h?rev=372874&r1=372873&r2=372874&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineRegionInfo.h (original)
+++ llvm/trunk/include/llvm/CodeGen/MachineRegionInfo.h Wed Sep 25 07:04:36 2019
@@ -22,7 +22,7 @@
namespace llvm {
-struct MachinePostDominatorTree;
+class MachinePostDominatorTree;
class MachineRegion;
class MachineRegionNode;
class MachineRegionInfo;
Modified: llvm/trunk/lib/CodeGen/MachinePostDominators.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachinePostDominators.cpp?rev=372874&r1=372873&r2=372874&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachinePostDominators.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachinePostDominators.cpp Wed Sep 25 07:04:36 2019
@@ -13,6 +13,8 @@
#include "llvm/CodeGen/MachinePostDominators.h"
+#include "llvm/ADT/STLExtras.h"
+
using namespace llvm;
namespace llvm {
@@ -25,33 +27,43 @@ char MachinePostDominatorTree::ID = 0;
INITIALIZE_PASS(MachinePostDominatorTree, "machinepostdomtree",
"MachinePostDominator Tree Construction", true, true)
-MachinePostDominatorTree::MachinePostDominatorTree() : MachineFunctionPass(ID) {
+MachinePostDominatorTree::MachinePostDominatorTree()
+ : MachineFunctionPass(ID), PDT(nullptr) {
initializeMachinePostDominatorTreePass(*PassRegistry::getPassRegistry());
- DT = new PostDomTreeBase<MachineBasicBlock>();
}
-FunctionPass *
-MachinePostDominatorTree::createMachinePostDominatorTreePass() {
+FunctionPass *MachinePostDominatorTree::createMachinePostDominatorTreePass() {
return new MachinePostDominatorTree();
}
-bool
-MachinePostDominatorTree::runOnMachineFunction(MachineFunction &F) {
- DT->recalculate(F);
+bool MachinePostDominatorTree::runOnMachineFunction(MachineFunction &F) {
+ PDT = std::make_unique<PostDomTreeT>();
+ PDT->recalculate(F);
return false;
}
-MachinePostDominatorTree::~MachinePostDominatorTree() {
- delete DT;
-}
-
-void
-MachinePostDominatorTree::getAnalysisUsage(AnalysisUsage &AU) const {
+void MachinePostDominatorTree::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
MachineFunctionPass::getAnalysisUsage(AU);
}
-void
-MachinePostDominatorTree::print(llvm::raw_ostream &OS, const Module *M) const {
- DT->print(OS);
+MachineBasicBlock *MachinePostDominatorTree::findNearestCommonDominator(
+ ArrayRef<MachineBasicBlock *> Blocks) const {
+ assert(!Blocks.empty());
+
+ MachineBasicBlock *NCD = Blocks.front();
+ for (MachineBasicBlock *BB : Blocks.drop_front()) {
+ NCD = PDT->findNearestCommonDominator(NCD, BB);
+
+ // Stop when the root is reached.
+ if (PDT->isVirtualRoot(PDT->getNode(NCD)))
+ return nullptr;
+ }
+
+ return NCD;
+}
+
+void MachinePostDominatorTree::print(llvm::raw_ostream &OS,
+ const Module *M) const {
+ PDT->print(OS);
}
Modified: llvm/trunk/lib/Target/AMDGPU/SILowerI1Copies.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AMDGPU/SILowerI1Copies.cpp?rev=372874&r1=372873&r2=372874&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AMDGPU/SILowerI1Copies.cpp (original)
+++ llvm/trunk/lib/Target/AMDGPU/SILowerI1Copies.cpp Wed Sep 25 07:04:36 2019
@@ -589,12 +589,12 @@ void SILowerI1Copies::lowerPhis() {
// Phis in a loop that are observed outside the loop receive a simple but
// conservatively correct treatment.
- MachineBasicBlock *PostDomBound = &MBB;
- for (MachineInstr &Use : MRI->use_instructions(DstReg)) {
- PostDomBound =
- PDT->findNearestCommonDominator(PostDomBound, Use.getParent());
- }
+ std::vector<MachineBasicBlock *> DomBlocks = {&MBB};
+ for (MachineInstr &Use : MRI->use_instructions(DstReg))
+ DomBlocks.push_back(Use.getParent());
+ MachineBasicBlock *PostDomBound =
+ PDT->findNearestCommonDominator(DomBlocks);
unsigned FoundLoopLevel = LF.findLoop(PostDomBound);
SSAUpdater.Initialize(DstReg);
@@ -711,12 +711,12 @@ void SILowerI1Copies::lowerCopiesToI1()
// Defs in a loop that are observed outside the loop must be transformed
// into appropriate bit manipulation.
- MachineBasicBlock *PostDomBound = &MBB;
- for (MachineInstr &Use : MRI->use_instructions(DstReg)) {
- PostDomBound =
- PDT->findNearestCommonDominator(PostDomBound, Use.getParent());
- }
+ std::vector<MachineBasicBlock *> DomBlocks = {&MBB};
+ for (MachineInstr &Use : MRI->use_instructions(DstReg))
+ DomBlocks.push_back(Use.getParent());
+ MachineBasicBlock *PostDomBound =
+ PDT->findNearestCommonDominator(DomBlocks);
unsigned FoundLoopLevel = LF.findLoop(PostDomBound);
if (FoundLoopLevel) {
SSAUpdater.Initialize(DstReg);
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