[llvm] r329644 - [PR16756] Use SSAUpdaterBulk in JumpThreading.
Michael Zolotukhin via llvm-commits
llvm-commits at lists.llvm.org
Mon Apr 9 16:37:37 PDT 2018
Author: mzolotukhin
Date: Mon Apr 9 16:37:37 2018
New Revision: 329644
URL: http://llvm.org/viewvc/llvm-project?rev=329644&view=rev
Log:
[PR16756] Use SSAUpdaterBulk in JumpThreading.
Summary:
SSAUpdater is a bottleneck in JumpThreading, and this patch improves the
situation by using SSAUpdaterBulk instead.
Compile time impact: no noticable changes on CTMark, a big improvement
on the test from PR16756.
Reviewers: dberlin, davide, MatzeB
Subscribers: llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D44282
Modified:
llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp?rev=329644&r1=329643&r2=329644&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp Mon Apr 9 16:37:37 2018
@@ -66,6 +66,7 @@
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
+#include "llvm/Transforms/Utils/SSAUpdaterBulk.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include <algorithm>
#include <cassert>
@@ -1989,9 +1990,13 @@ bool JumpThreadingPass::ThreadEdge(Basic
// 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
// 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) {
+ UsesToRename.clear();
+
// Scan all uses of this instruction to see if it is used outside of its
// block, and if so, record them in UsesToRename.
for (Use &U : I.uses()) {
@@ -2008,19 +2013,15 @@ bool JumpThreadingPass::ThreadEdge(Basic
// If there are no uses outside the block, we're done with this instruction.
if (UsesToRename.empty())
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. Rename all uses of I that are outside
- // its block to be uses of the appropriate PHI node etc. See ValuesInBlocks
- // with the two values we know.
- SSAUpdate.Initialize(I.getType(), I.getName());
- SSAUpdate.AddAvailableValue(BB, &I);
- SSAUpdate.AddAvailableValue(NewBB, ValueMapping[&I]);
-
- while (!UsesToRename.empty())
- SSAUpdate.RewriteUse(*UsesToRename.pop_back_val());
- DEBUG(dbgs() << "\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.
+ SSAUpdate.AddAvailableValue(VarNum, BB, &I);
+ SSAUpdate.AddAvailableValue(VarNum, NewBB, ValueMapping[&I]);
+ for (auto U : UsesToRename)
+ SSAUpdate.AddUse(VarNum, U);
+ VarNum++;
}
// Ok, NewBB is good to go. Update the terminator of PredBB to jump to
@@ -2037,6 +2038,10 @@ bool JumpThreadingPass::ThreadEdge(Basic
{DominatorTree::Insert, PredBB, NewBB},
{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
// over the new instructions and zap any that are constants or dead. This
// frequently happens because of phi translation.
More information about the llvm-commits
mailing list