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From 9cdff0785d5cf9effc8e922d3330311c4d3dda78 Mon Sep 17 00:00:00 2001
From: Naveen Saini <naveen.kumar.saini@intel.com>
Date: Fri, 27 Aug 2021 12:09:42 +0800
Subject: [PATCH 2/2] This patch is needed for avx512skx-i8x64 and
avx512skx-i16x32 targets.
This is combination of two commits:
- 0cd6712a7af0fa2702b5d4cc733500eb5e62e7d0 - stability fix.
- d8ad7cc0885f32104a7cd83c77191aec15fd684f - performance follow up.
Upstream-Status: Backport
Signed-off-by: Naveen Saini <naveen.kumar.saini@intel.com>
---
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 23 +++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 439a8367dabe..b1639c7f275d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -18471,6 +18471,26 @@ static SDValue narrowExtractedVectorLoad(SDNode *Extract, SelectionDAG &DAG) {
// Allow targets to opt-out.
EVT VT = Extract->getValueType(0);
+
+ // We can only create byte sized loads.
+ if (!VT.isByteSized())
+ return SDValue();
+
+ unsigned Index = ExtIdx->getZExtValue();
+ unsigned NumElts = VT.getVectorNumElements();
+
+ // If the index is a multiple of the extract element count, we can offset the
+ // address by the store size multiplied by the subvector index. Otherwise if
+ // the scalar type is byte sized, we can just use the index multiplied by
+ // the element size in bytes as the offset.
+ unsigned Offset;
+ if (Index % NumElts == 0)
+ Offset = (Index / NumElts) * VT.getStoreSize();
+ else if (VT.getScalarType().isByteSized())
+ Offset = Index * VT.getScalarType().getStoreSize();
+ else
+ return SDValue();
+
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
if (!TLI.shouldReduceLoadWidth(Ld, Ld->getExtensionType(), VT))
return SDValue();
@@ -18478,8 +18498,7 @@ static SDValue narrowExtractedVectorLoad(SDNode *Extract, SelectionDAG &DAG) {
// The narrow load will be offset from the base address of the old load if
// we are extracting from something besides index 0 (little-endian).
SDLoc DL(Extract);
- SDValue BaseAddr = Ld->getOperand(1);
- unsigned Offset = ExtIdx->getZExtValue() * VT.getScalarType().getStoreSize();
+ SDValue BaseAddr = Ld->getBasePtr();
// TODO: Use "BaseIndexOffset" to make this more effective.
SDValue NewAddr = DAG.getMemBasePlusOffset(BaseAddr, Offset, DL);
--
2.17.1
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