[llvm] 84cea60 - Revert "[SelectionDAGBuilder] Compute and cache PreferredExtendType on demand."

[Craig Topper via llvm-commits]

Author: Craig Topper
Date: 2021-08-19T08:42:05-07:00
New Revision: 84cea602f9425d48ea42cff2fc3771a7bd5df285

URL: https://github.com/llvm/llvm-project/commit/84cea602f9425d48ea42cff2fc3771a7bd5df285
DIFF: https://github.com/llvm/llvm-project/commit/84cea602f9425d48ea42cff2fc3771a7bd5df285.diff

LOG: Revert "[SelectionDAGBuilder] Compute and cache PreferredExtendType on demand."

This reverts commit add08c874147638e52d89eb07e40797dbc98d73b.

There was a compile time jump on tramp3d-v4 on https://llvm-compile-time-tracker.com/
Want to see if it goes away with this reverted.

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
    llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index 6a083047283e..85c6eca5775e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -57,6 +57,28 @@ static bool isUsedOutsideOfDefiningBlock(const Instruction *I) {
   return false;
 }
 
+static ISD::NodeType getPreferredExtendForValue(const Value *V) {
+  // For the users of the source value being used for compare instruction, if
+  // the number of signed predicate is greater than unsigned predicate, we
+  // prefer to use SIGN_EXTEND.
+  //
+  // With this optimization, we would be able to reduce some redundant sign or
+  // zero extension instruction, and eventually more machine CSE opportunities
+  // can be exposed.
+  ISD::NodeType ExtendKind = ISD::ANY_EXTEND;
+  unsigned NumOfSigned = 0, NumOfUnsigned = 0;
+  for (const User *U : V->users()) {
+    if (const auto *CI = dyn_cast<CmpInst>(U)) {
+      NumOfSigned += CI->isSigned();
+      NumOfUnsigned += CI->isUnsigned();
+    }
+  }
+  if (NumOfSigned > NumOfUnsigned)
+    ExtendKind = ISD::SIGN_EXTEND;
+
+  return ExtendKind;
+}
+
 void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
                                SelectionDAG *DAG) {
   Fn = &fn;
@@ -211,6 +233,9 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
       if (isUsedOutsideOfDefiningBlock(&I))
         if (!isa<AllocaInst>(I) || !StaticAllocaMap.count(cast<AllocaInst>(&I)))
           InitializeRegForValue(&I);
+
+      // Decide the preferred extend type for a value.
+      PreferredExtendType[&I] = getPreferredExtendForValue(&I);
     }
   }
 

diff  --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index ccc627317d66..eb2773580e04 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -9859,34 +9859,6 @@ SDValue TargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
   llvm_unreachable("LowerOperation not implemented for this target!");
 }
 
-static ISD::NodeType getPreferredExtendForValue(const Value *V) {
-  ISD::NodeType ExtendKind = ISD::ANY_EXTEND;
-
-  // TODO: Skip Arguments to match behavior when this was calculated only for
-  // instructions.
-  if (isa<Argument>(V))
-    return ExtendKind;
-
-  // For the users of the source value being used for compare instruction, if
-  // the number of signed predicate is greater than unsigned predicate, we
-  // prefer to use SIGN_EXTEND.
-  //
-  // With this optimization, we would be able to reduce some redundant sign or
-  // zero extension instruction, and eventually more machine CSE opportunities
-  // can be exposed.
-  unsigned NumOfSigned = 0, NumOfUnsigned = 0;
-  for (const User *U : V->users()) {
-    if (const auto *CI = dyn_cast<CmpInst>(U)) {
-      NumOfSigned += CI->isSigned();
-      NumOfUnsigned += CI->isUnsigned();
-    }
-  }
-  if (NumOfSigned > NumOfUnsigned)
-    ExtendKind = ISD::SIGN_EXTEND;
-
-  return ExtendKind;
-}
-
 void
 SelectionDAGBuilder::CopyValueToVirtualRegister(const Value *V, unsigned Reg) {
   SDValue Op = getNonRegisterValue(V);
@@ -9903,12 +9875,10 @@ SelectionDAGBuilder::CopyValueToVirtualRegister(const Value *V, unsigned Reg) {
                    None); // This is not an ABI copy.
   SDValue Chain = DAG.getEntryNode();
 
-  // Look up the preferred extend kind if we've already computed it. Otherwise,
-  // compute it and cache it.
-  ISD::NodeType &ExtendType = FuncInfo.PreferredExtendType[V];
-  if (!ExtendType)
-    ExtendType = getPreferredExtendForValue(V);
-
+  ISD::NodeType ExtendType = ISD::ANY_EXTEND;
+  auto PreferredExtendIt = FuncInfo.PreferredExtendType.find(V);
+  if (PreferredExtendIt != FuncInfo.PreferredExtendType.end())
+    ExtendType = PreferredExtendIt->second;
   RFV.getCopyToRegs(Op, DAG, getCurSDLoc(), Chain, nullptr, V, ExtendType);
   PendingExports.push_back(Chain);
 }