[llvm] [SelectionDAGBuilder] Remove NodeMap updates from getValueImpl. NFC (PR #126849)

[Craig Topper via llvm-commits]

https://github.com/topperc updated https://github.com/llvm/llvm-project/pull/126849

>From cd4006f3bf5f0da752da8a32d8fec0f56e539ab6 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Tue, 11 Feb 2025 19:37:32 -0800
Subject: [PATCH 1/2] [SelectionDAGBuidler] Remove NodeMap updates from
 getValueImpl. NFC

Both callers already put the result in NodeMap immediately after
the call.

A long time ago getValueImpl's body was part of getValue. There was
reference taken to NodeMap[V] taken at the beginning and that reference
was used to update the map. But getValue is recursive for the creation of
builder_vector. The recursion may invalidate that reference so the
builder_vector code couldn't use that reference and had to update the
map directly. Later another recursive case was added that was added
and to fix the stale reference, getValueImpl was introduced with the
map update being done by the caller. Since build_vector had its own
NodeMap update, I guess it was missed in that update. The other NodeMap
update this patch removes were probably just copied from the build_vector
code without knowing it was unnecessary.
---
 llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 5a5596a542f72..8ebdb7058357f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1855,7 +1855,7 @@ SDValue SelectionDAGBuilder::getValueImpl(const Value *V) {
 
       if (isa<ArrayType>(CDS->getType()))
         return DAG.getMergeValues(Ops, getCurSDLoc());
-      return NodeMap[V] = DAG.getBuildVector(VT, getCurSDLoc(), Ops);
+      return DAG.getBuildVector(VT, getCurSDLoc(), Ops);
     }
 
     if (C->getType()->isStructTy() || C->getType()->isArrayTy()) {
@@ -1898,7 +1898,7 @@ SDValue SelectionDAGBuilder::getValueImpl(const Value *V) {
 
     if (VT.isRISCVVectorTuple()) {
       assert(C->isNullValue() && "Can only zero this target type!");
-      return NodeMap[V] = DAG.getNode(
+      return DAG.getNode(
                  ISD::BITCAST, getCurSDLoc(), VT,
                  DAG.getNode(
                      ISD::SPLAT_VECTOR, getCurSDLoc(),
@@ -1918,7 +1918,7 @@ SDValue SelectionDAGBuilder::getValueImpl(const Value *V) {
       for (unsigned i = 0; i != NumElements; ++i)
         Ops.push_back(getValue(CV->getOperand(i)));
 
-      return NodeMap[V] = DAG.getBuildVector(VT, getCurSDLoc(), Ops);
+      return DAG.getBuildVector(VT, getCurSDLoc(), Ops);
     }
 
     if (isa<ConstantAggregateZero>(C)) {
@@ -1931,7 +1931,7 @@ SDValue SelectionDAGBuilder::getValueImpl(const Value *V) {
       else
         Op = DAG.getConstant(0, getCurSDLoc(), EltVT);
 
-      return NodeMap[V] = DAG.getSplat(VT, getCurSDLoc(), Op);
+      return DAG.getSplat(VT, getCurSDLoc(), Op);
     }
 
     llvm_unreachable("Unknown vector constant");

>From 871d2015082fb6580993124906865ab791efa640 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Tue, 11 Feb 2025 22:13:16 -0800
Subject: [PATCH 2/2] fixup! clang-format

---
 .../CodeGen/SelectionDAG/SelectionDAGBuilder.cpp    | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 8ebdb7058357f..cac25fd7c1025 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1899,13 +1899,12 @@ SDValue SelectionDAGBuilder::getValueImpl(const Value *V) {
     if (VT.isRISCVVectorTuple()) {
       assert(C->isNullValue() && "Can only zero this target type!");
       return DAG.getNode(
-                 ISD::BITCAST, getCurSDLoc(), VT,
-                 DAG.getNode(
-                     ISD::SPLAT_VECTOR, getCurSDLoc(),
-                     EVT::getVectorVT(*DAG.getContext(), MVT::i8,
-                                      VT.getSizeInBits().getKnownMinValue() / 8,
-                                      true),
-                     DAG.getConstant(0, getCurSDLoc(), MVT::getIntegerVT(8))));
+          ISD::BITCAST, getCurSDLoc(), VT,
+          DAG.getNode(
+              ISD::SPLAT_VECTOR, getCurSDLoc(),
+              EVT::getVectorVT(*DAG.getContext(), MVT::i8,
+                               VT.getSizeInBits().getKnownMinValue() / 8, true),
+              DAG.getConstant(0, getCurSDLoc(), MVT::getIntegerVT(8))));
     }
 
     VectorType *VecTy = cast<VectorType>(V->getType());