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[ExpandVectorPredication] Support vp.merge in foldEVLIntoMask. #157195

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merged 1 commit into from
Sep 6, 2025
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[ExpandVectorPredication] Support vp.merge in foldEVLIntoMask. #157195

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11 changes: 10 additions & 1 deletion llvm/lib/CodeGen/ExpandVectorPredication.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -527,6 +527,12 @@ std::pair<Value *, bool> CachingVPExpander::foldEVLIntoMask(VPIntrinsic &VPI) {

// Only VP intrinsics can have an %evl parameter.
Value *OldMaskParam = VPI.getMaskParam();
if (!OldMaskParam) {
assert(VPI.getIntrinsicID() == Intrinsic::vp_merge &&
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vp_select doesn't have a mask param either. Should we handle it here too?

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vp_select is speculatable so the equivalebt test from the bug report didn’t get here.

"Unexpected VP intrinsic without mask operand");
OldMaskParam = VPI.getArgOperand(0);
}

Value *OldEVLParam = VPI.getVectorLengthParam();
assert(OldMaskParam && "no mask param to fold the vl param into");
assert(OldEVLParam && "no EVL param to fold away");
Expand All @@ -538,7 +544,10 @@ std::pair<Value *, bool> CachingVPExpander::foldEVLIntoMask(VPIntrinsic &VPI) {
ElementCount ElemCount = VPI.getStaticVectorLength();
Value *VLMask = convertEVLToMask(Builder, OldEVLParam, ElemCount);
Value *NewMaskParam = Builder.CreateAnd(VLMask, OldMaskParam);
VPI.setMaskParam(NewMaskParam);
if (VPI.getIntrinsicID() == Intrinsic::vp_merge)
VPI.setArgOperand(0, NewMaskParam);
else
VPI.setMaskParam(NewMaskParam);

// Drop the %evl parameter.
discardEVLParameter(VPI);
Expand Down
14 changes: 13 additions & 1 deletion llvm/test/Transforms/PreISelIntrinsicLowering/expand-vp.ll
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Expand Up @@ -68,6 +68,7 @@ define void @test_vp_int_v8(<8 x i32> %i0, <8 x i32> %i1, <8 x i32> %i2, <8 x i3
%rE = call <8 x i32> @llvm.vp.ashr.v8i32(<8 x i32> %i0, <8 x i32> %i1, <8 x i1> %m, i32 %n)
%rF = call <8 x i32> @llvm.vp.lshr.v8i32(<8 x i32> %i0, <8 x i32> %i1, <8 x i1> %m, i32 %n)
%r10 = call <8 x i32> @llvm.vp.shl.v8i32(<8 x i32> %i0, <8 x i32> %i1, <8 x i1> %m, i32 %n)
%r11 = call <8 x i32> @llvm.vp.merge.v8i32(<8 x i1> %m, <8 x i32> %i0, <8 x i32> %i1, i32 %n)
ret void
}

Expand Down Expand Up @@ -111,6 +112,7 @@ define void @test_vp_int_vscale(<vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1,
%rE = call <vscale x 4 x i32> @llvm.vp.ashr.nxv4i32(<vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, <vscale x 4 x i1> %m, i32 %n)
%rF = call <vscale x 4 x i32> @llvm.vp.lshr.nxv4i32(<vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, <vscale x 4 x i1> %m, i32 %n)
%r10 = call <vscale x 4 x i32> @llvm.vp.shl.nxv4i32(<vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, <vscale x 4 x i1> %m, i32 %n)
%r11 = call <vscale x 4 x i32> @llvm.vp.merge.nxv4i32(<vscale x 4 x i1> %m, <vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, i32 %n)
ret void
}

Expand Down Expand Up @@ -322,6 +324,7 @@ define void @test_vp_cmp_v8(<8 x i32> %i0, <8 x i32> %i1, <8 x float> %f0, <8 x
; LEGAL_LEGAL-NEXT: %rE = call <8 x i32> @llvm.vp.ashr.v8i32(<8 x i32> %i0, <8 x i32> %i1, <8 x i1> %m, i32 %n)
; LEGAL_LEGAL-NEXT: %rF = call <8 x i32> @llvm.vp.lshr.v8i32(<8 x i32> %i0, <8 x i32> %i1, <8 x i1> %m, i32 %n)
; LEGAL_LEGAL-NEXT: %r10 = call <8 x i32> @llvm.vp.shl.v8i32(<8 x i32> %i0, <8 x i32> %i1, <8 x i1> %m, i32 %n)
; LEGAL_LEGAL-NEXT: %r11 = call <8 x i32> @llvm.vp.merge.v8i32(<8 x i1> %m, <8 x i32> %i0, <8 x i32> %i1, i32 %n)
; LEGAL_LEGAL-NEXT: ret void

; LEGAL_LEGAL:define void @test_vp_int_vscale(<vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, <vscale x 4 x i32> %i2, <vscale x 4 x i32> %f3, <vscale x 4 x i1> %m, i32 %n) {
Expand All @@ -342,6 +345,7 @@ define void @test_vp_cmp_v8(<8 x i32> %i0, <8 x i32> %i1, <8 x float> %f0, <8 x
; LEGAL_LEGAL-NEXT: %rE = call <vscale x 4 x i32> @llvm.vp.ashr.nxv4i32(<vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, <vscale x 4 x i1> %m, i32 %n)
; LEGAL_LEGAL-NEXT: %rF = call <vscale x 4 x i32> @llvm.vp.lshr.nxv4i32(<vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, <vscale x 4 x i1> %m, i32 %n)
; LEGAL_LEGAL-NEXT: %r10 = call <vscale x 4 x i32> @llvm.vp.shl.nxv4i32(<vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, <vscale x 4 x i1> %m, i32 %n)
; LEGAL_LEGAL-NEXT: %r11 = call <vscale x 4 x i32> @llvm.vp.merge.nxv4i32(<vscale x 4 x i1> %m, <vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, i32 %n)
; LEGAL_LEGAL-NEXT: ret void

; LEGAL_LEGAL: define void @test_vp_reduce_int_v4(i32 %start, <4 x i32> %vi, <4 x i1> %m, i32 %n) {
Expand Down Expand Up @@ -415,6 +419,11 @@ define void @test_vp_cmp_v8(<8 x i32> %i0, <8 x i32> %i1, <8 x float> %f0, <8 x
; DISCARD_LEGAL-NEXT: %rE = call <8 x i32> @llvm.vp.ashr.v8i32(<8 x i32> %i0, <8 x i32> %i1, <8 x i1> %m, i32 8)
; DISCARD_LEGAL-NEXT: %rF = call <8 x i32> @llvm.vp.lshr.v8i32(<8 x i32> %i0, <8 x i32> %i1, <8 x i1> %m, i32 8)
; DISCARD_LEGAL-NEXT: %r10 = call <8 x i32> @llvm.vp.shl.v8i32(<8 x i32> %i0, <8 x i32> %i1, <8 x i1> %m, i32 8)
; DISCARD_LEGAL-NEXT: [[NSPLATINS2:%.+]] = insertelement <8 x i32> poison, i32 %n, i64 0
; DISCARD_LEGAL-NEXT: [[NSPLAT2:%.+]] = shufflevector <8 x i32> [[NSPLATINS2]], <8 x i32> poison, <8 x i32> zeroinitializer
; DISCARD_LEGAL-NEXT: [[EVLMASK2:%.+]] = icmp ult <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>, [[NSPLAT2]]
; DISCARD_LEGAL-NEXT: [[NEWMASK2:%.+]] = and <8 x i1> [[EVLMASK2]], %m
; DISCARD_LEGAL-NEXT: %r11 = call <8 x i32> @llvm.vp.merge.v8i32(<8 x i1> [[NEWMASK2]], <8 x i32> %i0, <8 x i32> %i1, i32 8)
; DISCARD_LEGAL-NEXT: ret void

; TODO compute vscale only once and use caching.
Expand All @@ -431,7 +440,8 @@ define void @test_vp_cmp_v8(<8 x i32> %i0, <8 x i32> %i1, <8 x float> %f0, <8 x
; DISCARD_LEGAL: [[NEWM:%.+]] = and <vscale x 4 x i1> [[EVLM]], %m
; DISCARD_LEGAL: %r3 = call <vscale x 4 x i32> @llvm.vp.sdiv.nxv4i32(<vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, <vscale x 4 x i1> [[NEWM]], i32 %scalable_size{{.*}})
; DISCARD_LEGAL-NOT: %{{.+}} = call <vscale x 4 x i32> @llvm.vp.{{.*}}, i32 %n)
; DISCARD_LEGAL: ret void
; DISCARD_LEGAL: %r11 = call <vscale x 4 x i32> @llvm.vp.merge.nxv4i32(<vscale x 4 x i1> %{{.*}}, <vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, i32 %scalable_size{{.*}})
; DISCARD_LEGAL-NEXT: ret void

; DISCARD_LEGAL: define void @test_vp_reduce_int_v4(i32 %start, <4 x i32> %vi, <4 x i1> %m, i32 %n) {
; DISCARD_LEGAL-NEXT: [[NSPLATINS:%.+]] = insertelement <4 x i32> poison, i32 %n, i64 0
Expand Down Expand Up @@ -503,6 +513,7 @@ define void @test_vp_cmp_v8(<8 x i32> %i0, <8 x i32> %i1, <8 x float> %f0, <8 x
; CONVERT_LEGAL-NOT: %{{.+}} = call <8 x i32> @llvm.vp.ashr.v8i32(<8 x i32> %i0, <8 x i32> %i1, <8 x i1> %m, i32 8)
; CONVERT_LEGAL-NOT: %{{.+}} = call <8 x i32> @llvm.vp.lshr.v8i32(<8 x i32> %i0, <8 x i32> %i1, <8 x i1> %m, i32 8)
; CONVERT_LEGAL-NOT: %{{.+}} = call <8 x i32> @llvm.vp.shl.v8i32(<8 x i32> %i0, <8 x i32> %i1, <8 x i1> %m, i32 8)
; CONVERT_LEGAL: %r11 = call <8 x i32> @llvm.vp.merge.v8i32(<8 x i1> %{{.*}}, <8 x i32> %i0, <8 x i32> %i1, i32 8)
; CONVERT_LEGAL: ret void

; Similar to %evl discard, %mask legal but make sure the first VP intrinsic has a legal expansion
Expand All @@ -513,6 +524,7 @@ define void @test_vp_cmp_v8(<8 x i32> %i0, <8 x i32> %i1, <8 x float> %f0, <8 x
; CONVERT_LEGAL-NEXT: %scalable_size = mul nuw i32 %vscale, 4
; CONVERT_LEGAL-NEXT: %r0 = call <vscale x 4 x i32> @llvm.vp.add.nxv4i32(<vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, <vscale x 4 x i1> [[NEWM]], i32 %scalable_size)
; CONVERT_LEGAL-NOT: %{{.*}} = call <vscale x 4 x i32> @llvm.vp.{{.*}}, i32 %n)
; CONVERT_LEGAL: %r11 = call <vscale x 4 x i32> @llvm.vp.merge.nxv4i32(<vscale x 4 x i1> %{{.*}}, <vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, i32 %scalable_size{{.*}})
; CONVERT_LEGAL: ret void

; CONVERT_LEGAL: define void @test_vp_reduce_int_v4(i32 %start, <4 x i32> %vi, <4 x i1> %m, i32 %n) {
Expand Down