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Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading." one more time.

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Hopefully, changing set to vector removes nondeterminism detected by
some bots, or the new assert will catch something.

This reverts commit r330180.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330403 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Zolotukhin 2018-04-20 08:01:08 +00:00
parent e623ebc840
commit caacf23982
2 changed files with 50 additions and 16 deletions
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38
lib/Transforms/Scalar/JumpThreading.cpp
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@ -66,6 +66,7 @@
#include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h" #include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/SSAUpdater.h" #include "llvm/Transforms/Utils/SSAUpdater.h"
#include "llvm/Transforms/Utils/SSAUpdaterBulk.h"
#include "llvm/Transforms/Utils/ValueMapper.h" #include "llvm/Transforms/Utils/ValueMapper.h"
#include <algorithm> #include <algorithm>
#include <cassert> #include <cassert>
@ -1989,15 +1990,20 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
// now have to update all uses of the value to use either the original value, // now have to update all uses of the value to use either the original value,
// the cloned value, or some PHI derived value. This can require arbitrary // the cloned value, or some PHI derived value. This can require arbitrary
// PHI insertion, of which we are prepared to do, clean these up now. // PHI insertion, of which we are prepared to do, clean these up now.
SSAUpdater SSAUpdate; SSAUpdaterBulk SSAUpdate;
SmallVector<Use*, 16> UsesToRename;
unsigned VarNum = 0;
for (Instruction &I : *BB) { for (Instruction &I : *BB) {
SmallVector<Use*, 16> UsesToRename;
// Scan all uses of this instruction to see if it is used outside of its // Scan all uses of this instruction to see if it is used outside of its
// block, and if so, record them in UsesToRename. // block, and if so, record them in UsesToRename. Also, skip phi operands
// from PredBB - we'll remove them anyway.
for (Use &U : I.uses()) { for (Use &U : I.uses()) {
Instruction *User = cast<Instruction>(U.getUser()); Instruction *User = cast<Instruction>(U.getUser());
if (PHINode *UserPN = dyn_cast<PHINode>(User)) { if (PHINode *UserPN = dyn_cast<PHINode>(User)) {
if (UserPN->getIncomingBlock(U) == BB) if (UserPN->getIncomingBlock(U) == BB ||
UserPN->getIncomingBlock(U) == PredBB)
continue; continue;
} else if (User->getParent() == BB) } else if (User->getParent() == BB)
continue; continue;
@ -2008,19 +2014,15 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
// If there are no uses outside the block, we're done with this instruction. // If there are no uses outside the block, we're done with this instruction.
if (UsesToRename.empty()) if (UsesToRename.empty())
continue; continue;
SSAUpdate.AddVariable(VarNum, I.getName(), I.getType());
DEBUG(dbgs() << "JT: Renaming non-local uses of: " << I << "\n"); // We found a use of I outside of BB - we need to rename all uses of I that
// are outside its block to be uses of the appropriate PHI node etc.
// We found a use of I outside of BB. Rename all uses of I that are outside SSAUpdate.AddAvailableValue(VarNum, BB, &I);
// its block to be uses of the appropriate PHI node etc. See ValuesInBlocks SSAUpdate.AddAvailableValue(VarNum, NewBB, ValueMapping[&I]);
// with the two values we know. for (auto *U : UsesToRename)
SSAUpdate.Initialize(I.getType(), I.getName()); SSAUpdate.AddUse(VarNum, U);
SSAUpdate.AddAvailableValue(BB, &I); VarNum++;
SSAUpdate.AddAvailableValue(NewBB, ValueMapping[&I]);
while (!UsesToRename.empty())
SSAUpdate.RewriteUse(*UsesToRename.pop_back_val());
DEBUG(dbgs() << "\n");
} }
// Ok, NewBB is good to go. Update the terminator of PredBB to jump to // Ok, NewBB is good to go. Update the terminator of PredBB to jump to
@ -2037,6 +2039,10 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
{DominatorTree::Insert, PredBB, NewBB}, {DominatorTree::Insert, PredBB, NewBB},
{DominatorTree::Delete, PredBB, BB}}); {DominatorTree::Delete, PredBB, BB}});
// Apply all updates we queued with DDT and get the updated Dominator Tree.
DominatorTree *DT = &DDT->flush();
SSAUpdate.RewriteAllUses(DT);
// At this point, the IR is fully up to date and consistent. Do a quick scan // At this point, the IR is fully up to date and consistent. Do a quick scan
// over the new instructions and zap any that are constants or dead. This // over the new instructions and zap any that are constants or dead. This
// frequently happens because of phi translation. // frequently happens because of phi translation.

28
test/Transforms/JumpThreading/removed-use.ll Normal file
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@ -0,0 +1,28 @@
; RUN: opt -S < %s -jump-threading | FileCheck %s
; CHECK-LABEL: @foo
; CHECK: bb6:
; CHECK-NEXT: ret void
; CHECK: bb3:
; CHECK: br label %bb3
define void @foo() {
entry:
br i1 true, label %bb6, label %bb3
bb3:
%x0 = phi i32 [ undef, %entry ], [ %x1, %bb5 ]
%y = and i64 undef, 1
%p = icmp ne i64 %y, 0
br i1 %p, label %bb4, label %bb5
bb4:
br label %bb5
bb5:
%x1 = phi i32 [ %x0, %bb3 ], [ %x0, %bb4 ]
%z = phi i32 [ 0, %bb3 ], [ 1, %bb4 ]
%q = icmp eq i32 %z, 0
br i1 %q, label %bb3, label %bb6
bb6:
ret void
}