[llvm] r311381 - Revert "Reapply: [ADCE][Dominators] Teach ADCE to preserve dominators"
Sanjoy Das via llvm-commits
llvm-commits at lists.llvm.org
Mon Aug 21 13:39:18 PDT 2017
Author: sanjoy
Date: Mon Aug 21 13:39:18 2017
New Revision: 311381
URL: http://llvm.org/viewvc/llvm-project?rev=311381&view=rev
Log:
Revert "Reapply: [ADCE][Dominators] Teach ADCE to preserve dominators"
Summary: This partially reverts commit r311057 since it breaks ADCE. See PR34258.
Reviewers: kuhar
Subscribers: mcrosier, david2050, llvm-commits
Differential Revision: https://reviews.llvm.org/D36979
Removed:
llvm/trunk/test/Transforms/ADCE/domtree-DoubleDeletion.ll
llvm/trunk/test/Transforms/ADCE/unreachable.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/ADCE.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/ADCE.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ADCE.cpp?rev=311381&r1=311380&r2=311381&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/ADCE.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/ADCE.cpp Mon Aug 21 13:39:18 2017
@@ -27,7 +27,6 @@
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/DebugInfoMetadata.h"
-#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instructions.h"
@@ -90,10 +89,6 @@ struct BlockInfoType {
class AggressiveDeadCodeElimination {
Function &F;
-
- // ADCE does not use DominatorTree per se, but it updates it to preserve the
- // analysis.
- DominatorTree &DT;
PostDominatorTree &PDT;
/// Mapping of blocks to associated information, an element in BlockInfoVec.
@@ -162,10 +157,9 @@ class AggressiveDeadCodeElimination {
void makeUnconditional(BasicBlock *BB, BasicBlock *Target);
public:
- AggressiveDeadCodeElimination(Function &F, DominatorTree &DT,
- PostDominatorTree &PDT)
- : F(F), DT(DT), PDT(PDT) {}
- bool performDeadCodeElimination();
+ AggressiveDeadCodeElimination(Function &F, PostDominatorTree &PDT)
+ : F(F), PDT(PDT) {}
+ bool performDeadCodeElimination();
};
}
@@ -563,31 +557,14 @@ void AggressiveDeadCodeElimination::upda
}
assert((PreferredSucc && PreferredSucc->PostOrder > 0) &&
"Failed to find safe successor for dead branch");
-
- // Collect removed successors to update the (Post)DominatorTrees.
- SmallPtrSet<BasicBlock *, 4> RemovedSuccessors;
bool First = true;
for (auto *Succ : successors(BB)) {
- if (!First || Succ != PreferredSucc->BB) {
+ if (!First || Succ != PreferredSucc->BB)
Succ->removePredecessor(BB);
- RemovedSuccessors.insert(Succ);
- } else
+ else
First = false;
}
makeUnconditional(BB, PreferredSucc->BB);
-
- // Inform the dominators about the deleted CFG edges.
- for (auto *Succ : RemovedSuccessors) {
- // It might have happened that the same successor appeared multiple times
- // and the CFG edge wasn't really removed.
- if (Succ != PreferredSucc->BB) {
- DEBUG(dbgs() << "ADCE: Removing (Post)DomTree edge " << BB->getName()
- << " -> " << Succ->getName() << "\n");
- DT.deleteEdge(BB, Succ);
- PDT.deleteEdge(BB, Succ);
- }
- }
-
NumBranchesRemoved += 1;
}
}
@@ -632,9 +609,6 @@ void AggressiveDeadCodeElimination::make
InstInfo[NewTerm].Live = true;
if (const DILocation *DL = PredTerm->getDebugLoc())
NewTerm->setDebugLoc(DL);
-
- InstInfo.erase(PredTerm);
- PredTerm->eraseFromParent();
}
//===----------------------------------------------------------------------===//
@@ -643,16 +617,13 @@ void AggressiveDeadCodeElimination::make
//
//===----------------------------------------------------------------------===//
PreservedAnalyses ADCEPass::run(Function &F, FunctionAnalysisManager &FAM) {
- auto &DT = FAM.getResult<DominatorTreeAnalysis>(F);
auto &PDT = FAM.getResult<PostDominatorTreeAnalysis>(F);
- if (!AggressiveDeadCodeElimination(F, DT, PDT).performDeadCodeElimination())
+ if (!AggressiveDeadCodeElimination(F, PDT).performDeadCodeElimination())
return PreservedAnalyses::all();
PreservedAnalyses PA;
PA.preserveSet<CFGAnalyses>();
PA.preserve<GlobalsAA>();
- PA.preserve<DominatorTreeAnalysis>();
- PA.preserve<PostDominatorTreeAnalysis>();
return PA;
}
@@ -666,23 +637,14 @@ struct ADCELegacyPass : public FunctionP
bool runOnFunction(Function &F) override {
if (skipFunction(F))
return false;
-
- auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
auto &PDT = getAnalysis<PostDominatorTreeWrapperPass>().getPostDomTree();
- return AggressiveDeadCodeElimination(F, DT, PDT)
- .performDeadCodeElimination();
+ return AggressiveDeadCodeElimination(F, PDT).performDeadCodeElimination();
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
- // We require DominatorTree here only to update and thus preserve it.
- AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<PostDominatorTreeWrapperPass>();
if (!RemoveControlFlowFlag)
AU.setPreservesCFG();
- else {
- AU.addPreserved<DominatorTreeWrapperPass>();
- AU.addPreserved<PostDominatorTreeWrapperPass>();
- }
AU.addPreserved<GlobalsAAWrapperPass>();
}
};
@@ -691,7 +653,6 @@ struct ADCELegacyPass : public FunctionP
char ADCELegacyPass::ID = 0;
INITIALIZE_PASS_BEGIN(ADCELegacyPass, "adce",
"Aggressive Dead Code Elimination", false, false)
-INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
INITIALIZE_PASS_END(ADCELegacyPass, "adce", "Aggressive Dead Code Elimination",
false, false)
Removed: llvm/trunk/test/Transforms/ADCE/domtree-DoubleDeletion.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/domtree-DoubleDeletion.ll?rev=311380&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/domtree-DoubleDeletion.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/domtree-DoubleDeletion.ll (removed)
@@ -1,39 +0,0 @@
-; RUN: opt < %s -gvn -simplifycfg -adce | llvm-dis
-; RUN: opt < %s -gvn -simplifycfg -adce -verify-dom-info | llvm-dis
-
-; This test makes sure that the DominatorTree properly handles
-; deletion of edges that go to forward-unreachable regions.
-; In this case, %land.end is already forward unreachable when
-; the DT gets informed about the deletion of %entry -> %land.end.
-
- at a = common global i32 0, align 4
-
-define i32 @main() {
-entry:
- %retval = alloca i32, align 4
- store i32 0, i32* %retval, align 4
- %0 = load i32, i32* @a, align 4
- %cmp = icmp ne i32 %0, 1
- br i1 %cmp, label %land.rhs, label %land.end4
-
-land.rhs: ; preds = %entry
- %1 = load i32, i32* @a, align 4
- %tobool = icmp ne i32 %1, 0
- br i1 %tobool, label %land.rhs1, label %land.end
-
-land.rhs1: ; preds = %land.rhs
- br label %land.end
-
-land.end: ; preds = %land.rhs1, %land.rhs
- %2 = phi i1 [ false, %land.rhs ], [ true, %land.rhs1 ]
- %land.ext = zext i1 %2 to i32
- %conv = trunc i32 %land.ext to i16
- %conv2 = sext i16 %conv to i32
- %tobool3 = icmp ne i32 %conv2, 0
- br label %land.end4
-
-land.end4: ; preds = %land.end, %entry
- %3 = phi i1 [ false, %entry ], [ %tobool3, %land.end ]
- %land.ext5 = zext i1 %3 to i32
- ret i32 0
-}
Removed: llvm/trunk/test/Transforms/ADCE/unreachable.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/unreachable.ll?rev=311380&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/unreachable.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/unreachable.ll (removed)
@@ -1,18 +0,0 @@
-; RUN: opt < %s -adce -simplifycfg | llvm-dis
-; RUN: opt < %s -passes=adce | llvm-dis
-
-define i32 @Test(i32 %A, i32 %B) {
-BB1:
- br label %BB4
-
-BB2: ; No predecessors!
- br label %BB3
-
-BB3: ; preds = %BB4, %BB2
- %ret = phi i32 [ %X, %BB4 ], [ %B, %BB2 ] ; <i32> [#uses=1]
- ret i32 %ret
-
-BB4: ; preds = %BB1
- %X = phi i32 [ %A, %BB1 ] ; <i32> [#uses=1]
- br label %BB3
-}
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