[llvm] d713f0e - Revert "[MachineSSAUpdater] compile time improvement in GetValueInMiddleOfBlock"

[Serguei Katkov via llvm-commits]

Author: Serguei Katkov
Date: 2022-06-14T20:27:21+07:00
New Revision: d713f0eab8c4604c6308f1a0135b1d726bdc889b

URL: https://github.com/llvm/llvm-project/commit/d713f0eab8c4604c6308f1a0135b1d726bdc889b
DIFF: https://github.com/llvm/llvm-project/commit/d713f0eab8c4604c6308f1a0135b1d726bdc889b.diff

LOG: Revert "[MachineSSAUpdater] compile time improvement in GetValueInMiddleOfBlock"

It looks like it causes buildbot failures.
As an example: https://lab.llvm.org/buildbot/#/builders/121/builds/20364

Revert to investigate...

This reverts commit 6bf27918144cb843cf5ae9a93cb5f936730f3cce.

Added: 
    

Modified: 
    llvm/lib/CodeGen/MachineSSAUpdater.cpp
    llvm/lib/Transforms/Utils/SSAUpdater.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/MachineSSAUpdater.cpp b/llvm/lib/CodeGen/MachineSSAUpdater.cpp
index f58b0f77897d6..48076663ddf53 100644
--- a/llvm/lib/CodeGen/MachineSSAUpdater.cpp
+++ b/llvm/lib/CodeGen/MachineSSAUpdater.cpp
@@ -152,14 +152,6 @@ Register MachineSSAUpdater::GetValueInMiddleOfBlock(MachineBasicBlock *BB,
   if (!HasValueForBlock(BB))
     return GetValueAtEndOfBlockInternal(BB, ExistingValueOnly);
 
-  // Ok, we have already got a value for this block. If it is out of our block
-  // or it is a phi - we can re-use it as it will be defined in the middle of
-  // block as well.
-  Register defR = getAvailableVals(AV).lookup(BB);
-  if (auto I = MRI->getVRegDef(defR))
-    if (I->isPHI() || I->getParent() != BB)
-      return defR;
-
   // If there are no predecessors, just return undef.
   if (BB->pred_empty()) {
     // If we cannot insert new instructions, just return $noreg.

diff  --git a/llvm/lib/Transforms/Utils/SSAUpdater.cpp b/llvm/lib/Transforms/Utils/SSAUpdater.cpp
index 69c93b304260d..37019e3bf95be 100644
--- a/llvm/lib/Transforms/Utils/SSAUpdater.cpp
+++ b/llvm/lib/Transforms/Utils/SSAUpdater.cpp
@@ -100,14 +100,6 @@ Value *SSAUpdater::GetValueInMiddleOfBlock(BasicBlock *BB) {
   if (!HasValueForBlock(BB))
     return GetValueAtEndOfBlock(BB);
 
-  // Ok, we have already got a value for this block. If it is out of our block
-  // or it is a phi - we can re-use it as it will be defined in the middle of
-  // block as well.
-  Value *defV = FindValueForBlock(BB);
-  if (auto I = dyn_cast<Instruction>(defV))
-    if (isa<PHINode>(I) || I->getParent() != BB)
-      return defV;
-
   // Otherwise, we have the hard case.  Get the live-in values for each
   // predecessor.
   SmallVector<std::pair<BasicBlock *, Value *>, 8> PredValues;