[PATCH] D157132: [RISCVGatherScatterLowering] Support broadcast base pointer

[Philip Reames via Phabricator via llvm-commits]

reames created this revision.
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A broadcast base pointer is the same as a scalar base pointer for GEP semantics (when there's at least one other vector operand).  This is the form that SLP likes to emit, so we should handle it.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D157132

Files:
  llvm/lib/Target/RISCV/RISCVGatherScatterLowering.cpp
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-load-store.ll


Index: llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-load-store.ll
===================================================================
--- llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-load-store.ll
+++ llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-load-store.ll
@@ -947,3 +947,19 @@
 bb16:                                             ; preds = %bb4, %bb
   ret void
 }
+
+define <8 x i8> @broadcast_ptr_base(ptr %a) {
+; CHECK-LABEL: @broadcast_ptr_base(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = call <8 x i8> @llvm.riscv.masked.strided.load.v8i8.p0.i64(<8 x i8> poison, ptr [[A:%.*]], i64 64, <8 x i1> <i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true>)
+; CHECK-NEXT:    ret <8 x i8> [[TMP0]]
+;
+entry:
+  %0 = insertelement <8 x ptr> poison, ptr %a, i64 0
+  %1 = shufflevector <8 x ptr> %0, <8 x ptr> poison, <8 x i32> zeroinitializer
+  %2 = getelementptr i8, <8 x ptr> %1, <8 x i64> <i64 0, i64 64, i64 128, i64 192, i64 256, i64 320, i64 384, i64 448>
+  %3 = tail call <8 x i8> @llvm.masked.gather.v8i8.v8p0(<8 x ptr> %2, i32 1, <8 x i1> <i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true>, <8 x i8> poison)
+  ret <8 x i8> %3
+}
+
+declare <8 x i8> @llvm.masked.gather.v8i8.v8p0(<8 x ptr>, i32 immarg, <8 x i1>, <8 x i8>)
Index: llvm/lib/Target/RISCV/RISCVGatherScatterLowering.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVGatherScatterLowering.cpp
+++ llvm/lib/Target/RISCV/RISCVGatherScatterLowering.cpp
@@ -331,8 +331,12 @@
   SmallVector<Value *, 2> Ops(GEP->operands());
 
   // Base pointer needs to be a scalar.
-  if (Ops[0]->getType()->isVectorTy())
-    return std::make_pair(nullptr, nullptr);
+  Value *ScalarBase = Ops[0];
+  if (ScalarBase->getType()->isVectorTy()) {
+    ScalarBase = getSplatValue(ScalarBase);
+    if (!ScalarBase)
+      return std::make_pair(nullptr, nullptr);
+  }
 
   std::optional<unsigned> VecOperand;
   unsigned TypeScale = 0;
@@ -379,7 +383,7 @@
     Ops[*VecOperand] = Start;
     Type *SourceTy = GEP->getSourceElementType();
     Value *BasePtr =
-        Builder.CreateGEP(SourceTy, Ops[0], ArrayRef(Ops).drop_front());
+        Builder.CreateGEP(SourceTy, ScalarBase, ArrayRef(Ops).drop_front());
 
     // Convert stride to pointer size if needed.
     Type *IntPtrTy = DL->getIntPtrType(BasePtr->getType());
@@ -415,7 +419,7 @@
   Ops[*VecOperand] = BasePhi;
   Type *SourceTy = GEP->getSourceElementType();
   Value *BasePtr =
-      Builder.CreateGEP(SourceTy, Ops[0], ArrayRef(Ops).drop_front());
+      Builder.CreateGEP(SourceTy, ScalarBase, ArrayRef(Ops).drop_front());
 
   // Final adjustments to stride should go in the start block.
   Builder.SetInsertPoint(


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