[llvm] 3894a11 - [X86] combineConcatVectorOps - handle the load combines in the same place

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2023-12-08T14:54:50Z
New Revision: 3894a11acd1c8907c4d8a19a96d1ea398463af65

URL: https://github.com/llvm/llvm-project/commit/3894a11acd1c8907c4d8a19a96d1ea398463af65
DIFF: https://github.com/llvm/llvm-project/commit/3894a11acd1c8907c4d8a19a96d1ea398463af65.diff

LOG: [X86] combineConcatVectorOps - handle the load combines in the same place

The intention is to merge some of the concat folds of vector constant data to address some of the remaining regressions in #73509

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86ISelLowering.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 6d7c279f85935..f6c7cabdf64c0 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -54490,25 +54490,6 @@ static SDValue combineConcatVectorOps(const SDLoc &DL, MVT VT,
     if (Op0.getOpcode() == X86ISD::VBROADCAST)
       return DAG.getNode(Op0.getOpcode(), DL, VT, Op0.getOperand(0));
 
-    // If this simple subvector or scalar/subvector broadcast_load is inserted
-    // into both halves, use a larger broadcast_load. Update other uses to use
-    // an extracted subvector.
-    if (ISD::isNormalLoad(Op0.getNode()) ||
-        Op0.getOpcode() == X86ISD::VBROADCAST_LOAD ||
-        Op0.getOpcode() == X86ISD::SUBV_BROADCAST_LOAD) {
-      auto *Mem = cast<MemSDNode>(Op0);
-      unsigned Opc = Op0.getOpcode() == X86ISD::VBROADCAST_LOAD
-                         ? X86ISD::VBROADCAST_LOAD
-                         : X86ISD::SUBV_BROADCAST_LOAD;
-      if (SDValue BcastLd =
-              getBROADCAST_LOAD(Opc, DL, VT, Mem->getMemoryVT(), Mem, 0, DAG)) {
-        SDValue BcastSrc =
-            extractSubVector(BcastLd, 0, DAG, DL, Op0.getValueSizeInBits());
-        DAG.ReplaceAllUsesOfValueWith(Op0, BcastSrc);
-        return BcastLd;
-      }
-    }
-
     // concat_vectors(movddup(x),movddup(x)) -> broadcast(x)
     if (Op0.getOpcode() == X86ISD::MOVDDUP && VT == MVT::v4f64 &&
         (Subtarget.hasAVX2() ||
@@ -54995,6 +54976,28 @@ static SDValue combineConcatVectorOps(const SDLoc &DL, MVT VT,
     }
   }
 
+  // If this simple subvector or scalar/subvector broadcast_load is inserted
+  // into both halves, use a larger broadcast_load. Update other uses to use
+  // an extracted subvector.
+  if (IsSplat &&
+      (VT.is256BitVector() || (VT.is512BitVector() && Subtarget.hasAVX512()))) {
+    if (ISD::isNormalLoad(Op0.getNode()) ||
+        Op0.getOpcode() == X86ISD::VBROADCAST_LOAD ||
+        Op0.getOpcode() == X86ISD::SUBV_BROADCAST_LOAD) {
+      auto *Mem = cast<MemSDNode>(Op0);
+      unsigned Opc = Op0.getOpcode() == X86ISD::VBROADCAST_LOAD
+                         ? X86ISD::VBROADCAST_LOAD
+                         : X86ISD::SUBV_BROADCAST_LOAD;
+      if (SDValue BcastLd =
+              getBROADCAST_LOAD(Opc, DL, VT, Mem->getMemoryVT(), Mem, 0, DAG)) {
+        SDValue BcastSrc =
+            extractSubVector(BcastLd, 0, DAG, DL, Op0.getValueSizeInBits());
+        DAG.ReplaceAllUsesOfValueWith(Op0, BcastSrc);
+        return BcastLd;
+      }
+    }
+  }
+
   // Attempt to fold target constant loads.
   if (all_of(Ops, [](SDValue Op) { return getTargetConstantFromNode(Op); })) {
     SmallVector<APInt> EltBits;