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[LoongArch] Optimize insertelement containing variable index using compare+select #151131

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Merged
merged 3 commits into from
Jul 30, 2025
Merged

[LoongArch] Optimize insertelement containing variable index using compare+select #151131

merged 3 commits into from
Jul 30, 2025

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zhaoqi5
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@zhaoqi5 zhaoqi5 commented Jul 29, 2025

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llvmbot commented Jul 29, 2025

@llvm/pr-subscribers-backend-loongarch

Author: ZhaoQi (zhaoqi5)

Changes

Full diff: https://github.com/llvm/llvm-project/pull/151131.diff

3 Files Affected:

  • (modified) llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp (+33-1)
  • (modified) llvm/test/CodeGen/LoongArch/lasx/ir-instruction/insertelement.ll (+50-90)
  • (modified) llvm/test/CodeGen/LoongArch/lsx/ir-instruction/insertelement.ll (+50-48)
diff --git a/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
index d96136cddb3b0..6f01c7bd06111 100644
--- a/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
+++ b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
@@ -2621,8 +2621,40 @@ LoongArchTargetLowering::lowerEXTRACT_VECTOR_ELT(SDValue Op,
 SDValue
 LoongArchTargetLowering::lowerINSERT_VECTOR_ELT(SDValue Op,
                                                 SelectionDAG &DAG) const {
-  if (isa<ConstantSDNode>(Op->getOperand(2)))
+  MVT VT = Op.getSimpleValueType();
+  MVT EltVT = VT.getVectorElementType();
+  unsigned NumElts = VT.getVectorNumElements();
+  unsigned EltSizeInBits = EltVT.getScalarSizeInBits();
+  SDLoc DL(Op);
+  SDValue Op0 = Op.getOperand(0);
+  SDValue Op1 = Op.getOperand(1);
+  SDValue Op2 = Op.getOperand(2);
+
+  if (isa<ConstantSDNode>(Op2)) {
     return Op;
+  } else {
+    MVT IdxTy = MVT::getIntegerVT(EltSizeInBits);
+    MVT IdxVTy = MVT::getVectorVT(IdxTy, NumElts);
+
+    if (!isTypeLegal(VT) || !isTypeLegal(IdxVTy))
+      return SDValue();
+
+    SDValue SplatElt = DAG.getSplatBuildVector(VT, DL, Op1);
+    SDValue SplatIdx = DAG.getSplatBuildVector(IdxVTy, DL, Op2);
+
+    SmallVector<SDValue, 32> RawIndices;
+    for (unsigned i = 0; i < NumElts; ++i)
+      RawIndices.push_back(DAG.getConstant(i, DL, Subtarget.getGRLenVT()));
+    SDValue Indices = DAG.getBuildVector(IdxVTy, DL, RawIndices);
+
+    // insert vec, elt, idx
+    // =>
+    // select (splatidx == {0,1,2...}) ? splatelt : vec
+    SDValue SelectCC =
+        DAG.getSetCC(DL, IdxVTy, SplatIdx, Indices, ISD::CondCode::SETEQ);
+    return DAG.getNode(ISD::VSELECT, DL, VT, SelectCC, SplatElt, Op0);
+  }
+
   return SDValue();
 }
 
diff --git a/llvm/test/CodeGen/LoongArch/lasx/ir-instruction/insertelement.ll b/llvm/test/CodeGen/LoongArch/lasx/ir-instruction/insertelement.ll
index c1d4220fc1166..e5a85245710de 100644
--- a/llvm/test/CodeGen/LoongArch/lasx/ir-instruction/insertelement.ll
+++ b/llvm/test/CodeGen/LoongArch/lasx/ir-instruction/insertelement.ll
@@ -114,22 +114,15 @@ define void @insert_4xdouble(ptr %src, ptr %dst, double %in) nounwind {
 define void @insert_32xi8_idx(ptr %src, ptr %dst, i8 %in, i32 %idx) nounwind {
 ; CHECK-LABEL: insert_32xi8_idx:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi.d $sp, $sp, -96
-; CHECK-NEXT:    st.d $ra, $sp, 88 # 8-byte Folded Spill
-; CHECK-NEXT:    st.d $fp, $sp, 80 # 8-byte Folded Spill
-; CHECK-NEXT:    addi.d $fp, $sp, 96
-; CHECK-NEXT:    bstrins.d $sp, $zero, 4, 0
-; CHECK-NEXT:    xvld $xr0, $a0, 0
-; CHECK-NEXT:    xvst $xr0, $sp, 32
-; CHECK-NEXT:    addi.d $a0, $sp, 32
-; CHECK-NEXT:    bstrins.d $a0, $a3, 4, 0
-; CHECK-NEXT:    st.b $a2, $a0, 0
-; CHECK-NEXT:    xvld $xr0, $sp, 32
+; CHECK-NEXT:    pcalau12i $a4, %pc_hi20(.LCPI8_0)
+; CHECK-NEXT:    xvld $xr0, $a4, %pc_lo12(.LCPI8_0)
+; CHECK-NEXT:    xvld $xr1, $a0, 0
+; CHECK-NEXT:    bstrpick.d $a0, $a3, 31, 0
+; CHECK-NEXT:    xvreplgr2vr.b $xr2, $a0
+; CHECK-NEXT:    xvseq.b $xr0, $xr2, $xr0
+; CHECK-NEXT:    xvreplgr2vr.b $xr2, $a2
+; CHECK-NEXT:    xvbitsel.v $xr0, $xr1, $xr2, $xr0
 ; CHECK-NEXT:    xvst $xr0, $a1, 0
-; CHECK-NEXT:    addi.d $sp, $fp, -96
-; CHECK-NEXT:    ld.d $fp, $sp, 80 # 8-byte Folded Reload
-; CHECK-NEXT:    ld.d $ra, $sp, 88 # 8-byte Folded Reload
-; CHECK-NEXT:    addi.d $sp, $sp, 96
 ; CHECK-NEXT:    ret
   %v = load volatile <32 x i8>, ptr %src
   %v_new = insertelement <32 x i8> %v, i8 %in, i32 %idx
@@ -140,22 +133,15 @@ define void @insert_32xi8_idx(ptr %src, ptr %dst, i8 %in, i32 %idx) nounwind {
 define void @insert_16xi16_idx(ptr %src, ptr %dst, i16 %in, i32 %idx) nounwind {
 ; CHECK-LABEL: insert_16xi16_idx:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi.d $sp, $sp, -96
-; CHECK-NEXT:    st.d $ra, $sp, 88 # 8-byte Folded Spill
-; CHECK-NEXT:    st.d $fp, $sp, 80 # 8-byte Folded Spill
-; CHECK-NEXT:    addi.d $fp, $sp, 96
-; CHECK-NEXT:    bstrins.d $sp, $zero, 4, 0
-; CHECK-NEXT:    xvld $xr0, $a0, 0
-; CHECK-NEXT:    xvst $xr0, $sp, 32
-; CHECK-NEXT:    addi.d $a0, $sp, 32
-; CHECK-NEXT:    bstrins.d $a0, $a3, 4, 1
-; CHECK-NEXT:    st.h $a2, $a0, 0
-; CHECK-NEXT:    xvld $xr0, $sp, 32
+; CHECK-NEXT:    pcalau12i $a4, %pc_hi20(.LCPI9_0)
+; CHECK-NEXT:    xvld $xr0, $a4, %pc_lo12(.LCPI9_0)
+; CHECK-NEXT:    xvld $xr1, $a0, 0
+; CHECK-NEXT:    bstrpick.d $a0, $a3, 31, 0
+; CHECK-NEXT:    xvreplgr2vr.h $xr2, $a0
+; CHECK-NEXT:    xvseq.h $xr0, $xr2, $xr0
+; CHECK-NEXT:    xvreplgr2vr.h $xr2, $a2
+; CHECK-NEXT:    xvbitsel.v $xr0, $xr1, $xr2, $xr0
 ; CHECK-NEXT:    xvst $xr0, $a1, 0
-; CHECK-NEXT:    addi.d $sp, $fp, -96
-; CHECK-NEXT:    ld.d $fp, $sp, 80 # 8-byte Folded Reload
-; CHECK-NEXT:    ld.d $ra, $sp, 88 # 8-byte Folded Reload
-; CHECK-NEXT:    addi.d $sp, $sp, 96
 ; CHECK-NEXT:    ret
   %v = load volatile <16 x i16>, ptr %src
   %v_new = insertelement <16 x i16> %v, i16 %in, i32 %idx
@@ -166,22 +152,15 @@ define void @insert_16xi16_idx(ptr %src, ptr %dst, i16 %in, i32 %idx) nounwind {
 define void @insert_8xi32_idx(ptr %src, ptr %dst, i32 %in, i32 %idx) nounwind {
 ; CHECK-LABEL: insert_8xi32_idx:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi.d $sp, $sp, -96
-; CHECK-NEXT:    st.d $ra, $sp, 88 # 8-byte Folded Spill
-; CHECK-NEXT:    st.d $fp, $sp, 80 # 8-byte Folded Spill
-; CHECK-NEXT:    addi.d $fp, $sp, 96
-; CHECK-NEXT:    bstrins.d $sp, $zero, 4, 0
-; CHECK-NEXT:    xvld $xr0, $a0, 0
-; CHECK-NEXT:    xvst $xr0, $sp, 32
-; CHECK-NEXT:    addi.d $a0, $sp, 32
-; CHECK-NEXT:    bstrins.d $a0, $a3, 4, 2
-; CHECK-NEXT:    st.w $a2, $a0, 0
-; CHECK-NEXT:    xvld $xr0, $sp, 32
+; CHECK-NEXT:    pcalau12i $a4, %pc_hi20(.LCPI10_0)
+; CHECK-NEXT:    xvld $xr0, $a4, %pc_lo12(.LCPI10_0)
+; CHECK-NEXT:    xvld $xr1, $a0, 0
+; CHECK-NEXT:    bstrpick.d $a0, $a3, 31, 0
+; CHECK-NEXT:    xvreplgr2vr.w $xr2, $a0
+; CHECK-NEXT:    xvseq.w $xr0, $xr2, $xr0
+; CHECK-NEXT:    xvreplgr2vr.w $xr2, $a2
+; CHECK-NEXT:    xvbitsel.v $xr0, $xr1, $xr2, $xr0
 ; CHECK-NEXT:    xvst $xr0, $a1, 0
-; CHECK-NEXT:    addi.d $sp, $fp, -96
-; CHECK-NEXT:    ld.d $fp, $sp, 80 # 8-byte Folded Reload
-; CHECK-NEXT:    ld.d $ra, $sp, 88 # 8-byte Folded Reload
-; CHECK-NEXT:    addi.d $sp, $sp, 96
 ; CHECK-NEXT:    ret
   %v = load volatile <8 x i32>, ptr %src
   %v_new = insertelement <8 x i32> %v, i32 %in, i32 %idx
@@ -192,22 +171,15 @@ define void @insert_8xi32_idx(ptr %src, ptr %dst, i32 %in, i32 %idx) nounwind {
 define void @insert_4xi64_idx(ptr %src, ptr %dst, i64 %in, i32 %idx) nounwind {
 ; CHECK-LABEL: insert_4xi64_idx:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi.d $sp, $sp, -96
-; CHECK-NEXT:    st.d $ra, $sp, 88 # 8-byte Folded Spill
-; CHECK-NEXT:    st.d $fp, $sp, 80 # 8-byte Folded Spill
-; CHECK-NEXT:    addi.d $fp, $sp, 96
-; CHECK-NEXT:    bstrins.d $sp, $zero, 4, 0
-; CHECK-NEXT:    xvld $xr0, $a0, 0
-; CHECK-NEXT:    xvst $xr0, $sp, 32
-; CHECK-NEXT:    addi.d $a0, $sp, 32
-; CHECK-NEXT:    bstrins.d $a0, $a3, 4, 3
-; CHECK-NEXT:    st.d $a2, $a0, 0
-; CHECK-NEXT:    xvld $xr0, $sp, 32
+; CHECK-NEXT:    pcalau12i $a4, %pc_hi20(.LCPI11_0)
+; CHECK-NEXT:    xvld $xr0, $a4, %pc_lo12(.LCPI11_0)
+; CHECK-NEXT:    xvld $xr1, $a0, 0
+; CHECK-NEXT:    bstrpick.d $a0, $a3, 31, 0
+; CHECK-NEXT:    xvreplgr2vr.d $xr2, $a0
+; CHECK-NEXT:    xvseq.d $xr0, $xr2, $xr0
+; CHECK-NEXT:    xvreplgr2vr.d $xr2, $a2
+; CHECK-NEXT:    xvbitsel.v $xr0, $xr1, $xr2, $xr0
 ; CHECK-NEXT:    xvst $xr0, $a1, 0
-; CHECK-NEXT:    addi.d $sp, $fp, -96
-; CHECK-NEXT:    ld.d $fp, $sp, 80 # 8-byte Folded Reload
-; CHECK-NEXT:    ld.d $ra, $sp, 88 # 8-byte Folded Reload
-; CHECK-NEXT:    addi.d $sp, $sp, 96
 ; CHECK-NEXT:    ret
   %v = load volatile <4 x i64>, ptr %src
   %v_new = insertelement <4 x i64> %v, i64 %in, i32 %idx
@@ -218,22 +190,16 @@ define void @insert_4xi64_idx(ptr %src, ptr %dst, i64 %in, i32 %idx) nounwind {
 define void @insert_8xfloat_idx(ptr %src, ptr %dst, float %in, i32 %idx) nounwind {
 ; CHECK-LABEL: insert_8xfloat_idx:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi.d $sp, $sp, -96
-; CHECK-NEXT:    st.d $ra, $sp, 88 # 8-byte Folded Spill
-; CHECK-NEXT:    st.d $fp, $sp, 80 # 8-byte Folded Spill
-; CHECK-NEXT:    addi.d $fp, $sp, 96
-; CHECK-NEXT:    bstrins.d $sp, $zero, 4, 0
-; CHECK-NEXT:    xvld $xr1, $a0, 0
-; CHECK-NEXT:    xvst $xr1, $sp, 32
-; CHECK-NEXT:    addi.d $a0, $sp, 32
-; CHECK-NEXT:    bstrins.d $a0, $a2, 4, 2
-; CHECK-NEXT:    fst.s $fa0, $a0, 0
-; CHECK-NEXT:    xvld $xr0, $sp, 32
+; CHECK-NEXT:    # kill: def $f0 killed $f0 def $xr0
+; CHECK-NEXT:    pcalau12i $a3, %pc_hi20(.LCPI12_0)
+; CHECK-NEXT:    xvld $xr1, $a3, %pc_lo12(.LCPI12_0)
+; CHECK-NEXT:    xvld $xr2, $a0, 0
+; CHECK-NEXT:    bstrpick.d $a0, $a2, 31, 0
+; CHECK-NEXT:    xvreplgr2vr.w $xr3, $a0
+; CHECK-NEXT:    xvseq.w $xr1, $xr3, $xr1
+; CHECK-NEXT:    xvreplve0.w $xr0, $xr0
+; CHECK-NEXT:    xvbitsel.v $xr0, $xr2, $xr0, $xr1
 ; CHECK-NEXT:    xvst $xr0, $a1, 0
-; CHECK-NEXT:    addi.d $sp, $fp, -96
-; CHECK-NEXT:    ld.d $fp, $sp, 80 # 8-byte Folded Reload
-; CHECK-NEXT:    ld.d $ra, $sp, 88 # 8-byte Folded Reload
-; CHECK-NEXT:    addi.d $sp, $sp, 96
 ; CHECK-NEXT:    ret
   %v = load volatile <8 x float>, ptr %src
   %v_new = insertelement <8 x float> %v, float %in, i32 %idx
@@ -244,22 +210,16 @@ define void @insert_8xfloat_idx(ptr %src, ptr %dst, float %in, i32 %idx) nounwin
 define void @insert_4xdouble_idx(ptr %src, ptr %dst, double %in, i32 %idx) nounwind {
 ; CHECK-LABEL: insert_4xdouble_idx:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi.d $sp, $sp, -96
-; CHECK-NEXT:    st.d $ra, $sp, 88 # 8-byte Folded Spill
-; CHECK-NEXT:    st.d $fp, $sp, 80 # 8-byte Folded Spill
-; CHECK-NEXT:    addi.d $fp, $sp, 96
-; CHECK-NEXT:    bstrins.d $sp, $zero, 4, 0
-; CHECK-NEXT:    xvld $xr1, $a0, 0
-; CHECK-NEXT:    xvst $xr1, $sp, 32
-; CHECK-NEXT:    addi.d $a0, $sp, 32
-; CHECK-NEXT:    bstrins.d $a0, $a2, 4, 3
-; CHECK-NEXT:    fst.d $fa0, $a0, 0
-; CHECK-NEXT:    xvld $xr0, $sp, 32
+; CHECK-NEXT:    # kill: def $f0_64 killed $f0_64 def $xr0
+; CHECK-NEXT:    pcalau12i $a3, %pc_hi20(.LCPI13_0)
+; CHECK-NEXT:    xvld $xr1, $a3, %pc_lo12(.LCPI13_0)
+; CHECK-NEXT:    xvld $xr2, $a0, 0
+; CHECK-NEXT:    bstrpick.d $a0, $a2, 31, 0
+; CHECK-NEXT:    xvreplgr2vr.d $xr3, $a0
+; CHECK-NEXT:    xvseq.d $xr1, $xr3, $xr1
+; CHECK-NEXT:    xvreplve0.d $xr0, $xr0
+; CHECK-NEXT:    xvbitsel.v $xr0, $xr2, $xr0, $xr1
 ; CHECK-NEXT:    xvst $xr0, $a1, 0
-; CHECK-NEXT:    addi.d $sp, $fp, -96
-; CHECK-NEXT:    ld.d $fp, $sp, 80 # 8-byte Folded Reload
-; CHECK-NEXT:    ld.d $ra, $sp, 88 # 8-byte Folded Reload
-; CHECK-NEXT:    addi.d $sp, $sp, 96
 ; CHECK-NEXT:    ret
   %v = load volatile <4 x double>, ptr %src
   %v_new = insertelement <4 x double> %v, double %in, i32 %idx
diff --git a/llvm/test/CodeGen/LoongArch/lsx/ir-instruction/insertelement.ll b/llvm/test/CodeGen/LoongArch/lsx/ir-instruction/insertelement.ll
index c73252bd1335f..4bb1941724dc6 100644
--- a/llvm/test/CodeGen/LoongArch/lsx/ir-instruction/insertelement.ll
+++ b/llvm/test/CodeGen/LoongArch/lsx/ir-instruction/insertelement.ll
@@ -84,15 +84,15 @@ define void @insert_2xdouble(ptr %src, ptr %dst, double %ins) nounwind {
 define void @insert_16xi8_idx(ptr %src, ptr %dst, i8 %ins, i32 %idx) nounwind {
 ; CHECK-LABEL: insert_16xi8_idx:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi.d $sp, $sp, -16
-; CHECK-NEXT:    vld $vr0, $a0, 0
-; CHECK-NEXT:    vst $vr0, $sp, 0
-; CHECK-NEXT:    addi.d $a0, $sp, 0
-; CHECK-NEXT:    bstrins.d $a0, $a3, 3, 0
-; CHECK-NEXT:    st.b $a2, $a0, 0
-; CHECK-NEXT:    vld $vr0, $sp, 0
+; CHECK-NEXT:    pcalau12i $a4, %pc_hi20(.LCPI6_0)
+; CHECK-NEXT:    vld $vr0, $a4, %pc_lo12(.LCPI6_0)
+; CHECK-NEXT:    vld $vr1, $a0, 0
+; CHECK-NEXT:    bstrpick.d $a0, $a3, 31, 0
+; CHECK-NEXT:    vreplgr2vr.b $vr2, $a0
+; CHECK-NEXT:    vseq.b $vr0, $vr2, $vr0
+; CHECK-NEXT:    vreplgr2vr.b $vr2, $a2
+; CHECK-NEXT:    vbitsel.v $vr0, $vr1, $vr2, $vr0
 ; CHECK-NEXT:    vst $vr0, $a1, 0
-; CHECK-NEXT:    addi.d $sp, $sp, 16
 ; CHECK-NEXT:    ret
   %v = load volatile <16 x i8>, ptr %src
   %v_new = insertelement <16 x i8> %v, i8 %ins, i32 %idx
@@ -103,15 +103,15 @@ define void @insert_16xi8_idx(ptr %src, ptr %dst, i8 %ins, i32 %idx) nounwind {
 define void @insert_8xi16_idx(ptr %src, ptr %dst, i16 %ins, i32 %idx) nounwind {
 ; CHECK-LABEL: insert_8xi16_idx:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi.d $sp, $sp, -16
-; CHECK-NEXT:    vld $vr0, $a0, 0
-; CHECK-NEXT:    vst $vr0, $sp, 0
-; CHECK-NEXT:    addi.d $a0, $sp, 0
-; CHECK-NEXT:    bstrins.d $a0, $a3, 3, 1
-; CHECK-NEXT:    st.h $a2, $a0, 0
-; CHECK-NEXT:    vld $vr0, $sp, 0
+; CHECK-NEXT:    pcalau12i $a4, %pc_hi20(.LCPI7_0)
+; CHECK-NEXT:    vld $vr0, $a4, %pc_lo12(.LCPI7_0)
+; CHECK-NEXT:    vld $vr1, $a0, 0
+; CHECK-NEXT:    bstrpick.d $a0, $a3, 31, 0
+; CHECK-NEXT:    vreplgr2vr.h $vr2, $a0
+; CHECK-NEXT:    vseq.h $vr0, $vr2, $vr0
+; CHECK-NEXT:    vreplgr2vr.h $vr2, $a2
+; CHECK-NEXT:    vbitsel.v $vr0, $vr1, $vr2, $vr0
 ; CHECK-NEXT:    vst $vr0, $a1, 0
-; CHECK-NEXT:    addi.d $sp, $sp, 16
 ; CHECK-NEXT:    ret
   %v = load volatile <8 x i16>, ptr %src
   %v_new = insertelement <8 x i16> %v, i16 %ins, i32 %idx
@@ -122,15 +122,15 @@ define void @insert_8xi16_idx(ptr %src, ptr %dst, i16 %ins, i32 %idx) nounwind {
 define void @insert_4xi32_idx(ptr %src, ptr %dst, i32 %ins, i32 %idx) nounwind {
 ; CHECK-LABEL: insert_4xi32_idx:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi.d $sp, $sp, -16
-; CHECK-NEXT:    vld $vr0, $a0, 0
-; CHECK-NEXT:    vst $vr0, $sp, 0
-; CHECK-NEXT:    addi.d $a0, $sp, 0
-; CHECK-NEXT:    bstrins.d $a0, $a3, 3, 2
-; CHECK-NEXT:    st.w $a2, $a0, 0
-; CHECK-NEXT:    vld $vr0, $sp, 0
+; CHECK-NEXT:    pcalau12i $a4, %pc_hi20(.LCPI8_0)
+; CHECK-NEXT:    vld $vr0, $a4, %pc_lo12(.LCPI8_0)
+; CHECK-NEXT:    vld $vr1, $a0, 0
+; CHECK-NEXT:    bstrpick.d $a0, $a3, 31, 0
+; CHECK-NEXT:    vreplgr2vr.w $vr2, $a0
+; CHECK-NEXT:    vseq.w $vr0, $vr2, $vr0
+; CHECK-NEXT:    vreplgr2vr.w $vr2, $a2
+; CHECK-NEXT:    vbitsel.v $vr0, $vr1, $vr2, $vr0
 ; CHECK-NEXT:    vst $vr0, $a1, 0
-; CHECK-NEXT:    addi.d $sp, $sp, 16
 ; CHECK-NEXT:    ret
   %v = load volatile <4 x i32>, ptr %src
   %v_new = insertelement <4 x i32> %v, i32 %ins, i32 %idx
@@ -141,15 +141,15 @@ define void @insert_4xi32_idx(ptr %src, ptr %dst, i32 %ins, i32 %idx) nounwind {
 define void @insert_2xi64_idx(ptr %src, ptr %dst, i64 %ins, i32 %idx) nounwind {
 ; CHECK-LABEL: insert_2xi64_idx:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi.d $sp, $sp, -16
-; CHECK-NEXT:    vld $vr0, $a0, 0
-; CHECK-NEXT:    vst $vr0, $sp, 0
-; CHECK-NEXT:    addi.d $a0, $sp, 0
-; CHECK-NEXT:    bstrins.d $a0, $a3, 3, 3
-; CHECK-NEXT:    st.d $a2, $a0, 0
-; CHECK-NEXT:    vld $vr0, $sp, 0
+; CHECK-NEXT:    pcalau12i $a4, %pc_hi20(.LCPI9_0)
+; CHECK-NEXT:    vld $vr0, $a4, %pc_lo12(.LCPI9_0)
+; CHECK-NEXT:    vld $vr1, $a0, 0
+; CHECK-NEXT:    bstrpick.d $a0, $a3, 31, 0
+; CHECK-NEXT:    vreplgr2vr.d $vr2, $a0
+; CHECK-NEXT:    vseq.d $vr0, $vr2, $vr0
+; CHECK-NEXT:    vreplgr2vr.d $vr2, $a2
+; CHECK-NEXT:    vbitsel.v $vr0, $vr1, $vr2, $vr0
 ; CHECK-NEXT:    vst $vr0, $a1, 0
-; CHECK-NEXT:    addi.d $sp, $sp, 16
 ; CHECK-NEXT:    ret
   %v = load volatile <2 x i64>, ptr %src
   %v_new = insertelement <2 x i64> %v, i64 %ins, i32 %idx
@@ -160,15 +160,16 @@ define void @insert_2xi64_idx(ptr %src, ptr %dst, i64 %ins, i32 %idx) nounwind {
 define void @insert_4xfloat_idx(ptr %src, ptr %dst, float %ins, i32 %idx) nounwind {
 ; CHECK-LABEL: insert_4xfloat_idx:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi.d $sp, $sp, -16
-; CHECK-NEXT:    vld $vr1, $a0, 0
-; CHECK-NEXT:    vst $vr1, $sp, 0
-; CHECK-NEXT:    addi.d $a0, $sp, 0
-; CHECK-NEXT:    bstrins.d $a0, $a2, 3, 2
-; CHECK-NEXT:    fst.s $fa0, $a0, 0
-; CHECK-NEXT:    vld $vr0, $sp, 0
+; CHECK-NEXT:    # kill: def $f0 killed $f0 def $vr0
+; CHECK-NEXT:    pcalau12i $a3, %pc_hi20(.LCPI10_0)
+; CHECK-NEXT:    vld $vr1, $a3, %pc_lo12(.LCPI10_0)
+; CHECK-NEXT:    vld $vr2, $a0, 0
+; CHECK-NEXT:    bstrpick.d $a0, $a2, 31, 0
+; CHECK-NEXT:    vreplgr2vr.w $vr3, $a0
+; CHECK-NEXT:    vseq.w $vr1, $vr3, $vr1
+; CHECK-NEXT:    vreplvei.w $vr0, $vr0, 0
+; CHECK-NEXT:    vbitsel.v $vr0, $vr2, $vr0, $vr1
 ; CHECK-NEXT:    vst $vr0, $a1, 0
-; CHECK-NEXT:    addi.d $sp, $sp, 16
 ; CHECK-NEXT:    ret
   %v = load volatile <4 x float>, ptr %src
   %v_new = insertelement <4 x float> %v, float %ins, i32 %idx
@@ -179,15 +180,16 @@ define void @insert_4xfloat_idx(ptr %src, ptr %dst, float %ins, i32 %idx) nounwi
 define void @insert_2xdouble_idx(ptr %src, ptr %dst, double %ins, i32 %idx) nounwind {
 ; CHECK-LABEL: insert_2xdouble_idx:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addi.d $sp, $sp, -16
-; CHECK-NEXT:    vld $vr1, $a0, 0
-; CHECK-NEXT:    vst $vr1, $sp, 0
-; CHECK-NEXT:    addi.d $a0, $sp, 0
-; CHECK-NEXT:    bstrins.d $a0, $a2, 3, 3
-; CHECK-NEXT:    fst.d $fa0, $a0, 0
-; CHECK-NEXT:    vld $vr0, $sp, 0
+; CHECK-NEXT:    # kill: def $f0_64 killed $f0_64 def $vr0
+; CHECK-NEXT:    pcalau12i $a3, %pc_hi20(.LCPI11_0)
+; CHECK-NEXT:    vld $vr1, $a3, %pc_lo12(.LCPI11_0)
+; CHECK-NEXT:    vld $vr2, $a0, 0
+; CHECK-NEXT:    bstrpick.d $a0, $a2, 31, 0
+; CHECK-NEXT:    vreplgr2vr.d $vr3, $a0
+; CHECK-NEXT:    vseq.d $vr1, $vr3, $vr1
+; CHECK-NEXT:    vreplvei.d $vr0, $vr0, 0
+; CHECK-NEXT:    vbitsel.v $vr0, $vr2, $vr0, $vr1
 ; CHECK-NEXT:    vst $vr0, $a1, 0
-; CHECK-NEXT:    addi.d $sp, $sp, 16
 ; CHECK-NEXT:    ret
   %v = load volatile <2 x double>, ptr %src
   %v_new = insertelement <2 x double> %v, double %ins, i32 %idx

@zhaoqi5 zhaoqi5 requested a review from SixWeining July 29, 2025 11:59
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zhaoqi5 commented Jul 29, 2025

According to https://llvm.org/docs/LangRef.html#insertelement-instruction:
If idx exceeds the length of val for a fixed-length vector, the result is a poison value.

Before this commit, seems that element in idx%eltnum changed if idx exceeds.
But the result vector will stay unchanged after this commit. (In fact, this behaves the same as when idx is a constant.)

Anyway, both are right?

SixWeining
SixWeining reviewed Jul 29, 2025
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llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp Outdated

SmallVector<SDValue, 32> RawIndices;
for (unsigned i = 0; i < NumElts; ++i)
RawIndices.push_back(DAG.getConstant(i, DL, Subtarget.getGRLenVT()));
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Suggested change
RawIndices.push_back(DAG.getConstant(i, DL, Subtarget.getGRLenVT()));
RawIndices.push_back(DAG.getConstant(i, DL, IdxTy));

I'm not sure...

  /// Return an ISD::BUILD_VECTOR node. The number of elements in VT,
  /// which must be a vector type, must match the number of operands in Ops.
  /// The operands must have the same type as (or, for integers, a type wider
  /// than) VT's element type.
  SDValue getBuildVector(EVT VT, const SDLoc &DL, ArrayRef<SDValue> Ops) {
    // VerifySDNode (via InsertNode) checks BUILD_VECTOR later.
    return getNode(ISD::BUILD_VECTOR, DL, VT, Ops);
  }

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getBuildVector() allows "The operands must have the same type as (or, for integers, a type wider than) VT's element type.". And we must ensure the elements of BUILD_VECTOR we built are type legal (ie. i64. i8/i16/i32 are illegal for loongarch64) at this point.

When I tried to use IdxTy here, assertion occurs:

Legalizing: t38: v16i8 = BUILD_VECTOR Constant:i8<0>, Constant:i8<1>, ... , Constant:i8<15>
llc: /.../llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp:991: void (anonymous namespace)::SelectionDAGLegalize::LegalizeOp(SDNode *): Assertion `(TLI.getTypeAction(*DAG.getContext(), Op.getValueType()) == TargetLowering::TypeLegal || Op.getOpcode() == ISD::TargetConstant || Op.getOpcode() == ISD::Register) && "Unexpected illegal type!"' failed.

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How about loongarch32 if we use Subtarget.getGRLenVT() when the vector is v{2,4}i64 or v{2,4}f64?

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v2i64/v4i64 is okay, because of the split of i64 in the initial selectiondag.
v2f64/v4f64 occur an assertion error when verifyNode().

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OK. Other tests may also have issues with loongarch32 + lsx/lasx. I think @heiher will handle them later.

@zhaoqi5 zhaoqi5 merged commit ece7a72 into main Jul 30, 2025
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@zhaoqi5 zhaoqi5 deleted the users/zhaoqi5/opt-insertelement-idx branch July 30, 2025 10:06
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