[llvm] 397e5a4 - [ExpandVectorPredication] Expand vp_merge and vp_select in expandPredication. (#157777)

[via llvm-commits]

Author: Craig Topper
Date: 2025-09-10T08:50:30-07:00
New Revision: 397e5a457ae8458fe4687c607c75be6ede453a25

URL: https://github.com/llvm/llvm-project/commit/397e5a457ae8458fe4687c607c75be6ede453a25
DIFF: https://github.com/llvm/llvm-project/commit/397e5a457ae8458fe4687c607c75be6ede453a25.diff

LOG: [ExpandVectorPredication] Expand vp_merge and vp_select in expandPredication. (#157777)

Added: 
    

Modified: 
    llvm/lib/CodeGen/ExpandVectorPredication.cpp
    llvm/test/Transforms/PreISelIntrinsicLowering/expand-vp.ll

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/ExpandVectorPredication.cpp b/llvm/lib/CodeGen/ExpandVectorPredication.cpp
index 75e8fe4965025..03abc042e5564 100644
--- a/llvm/lib/CodeGen/ExpandVectorPredication.cpp
+++ b/llvm/lib/CodeGen/ExpandVectorPredication.cpp
@@ -581,6 +581,14 @@ bool CachingVPExpander::expandPredication(VPIntrinsic &VPI) {
     replaceOperation(*NewNegOp, VPI);
     return NewNegOp;
   }
+  case Intrinsic::vp_select:
+  case Intrinsic::vp_merge: {
+    assert(maySpeculateLanes(VPI) || VPI.canIgnoreVectorLengthParam());
+    Value *NewSelectOp = Builder.CreateSelect(
+        VPI.getOperand(0), VPI.getOperand(1), VPI.getOperand(2), VPI.getName());
+    replaceOperation(*NewSelectOp, VPI);
+    return NewSelectOp;
+  }
   case Intrinsic::vp_abs:
   case Intrinsic::vp_smax:
   case Intrinsic::vp_smin:

diff  --git a/llvm/test/Transforms/PreISelIntrinsicLowering/expand-vp.ll b/llvm/test/Transforms/PreISelIntrinsicLowering/expand-vp.ll
index 4a9c64e306029..8fef808f193a9 100644
--- a/llvm/test/Transforms/PreISelIntrinsicLowering/expand-vp.ll
+++ b/llvm/test/Transforms/PreISelIntrinsicLowering/expand-vp.ll
@@ -208,8 +208,8 @@ define void @test_vp_cmp_v8(<8 x i32> %i0, <8 x i32> %i1, <8 x float> %f0, <8 x
 ; ALL-CONVERT-NEXT:  [[NSPLAT2:%.+]] = shufflevector <8 x i32> [[NINS2]], <8 x i32> poison, <8 x i32> zeroinitializer
 ; ALL-CONVERT-NEXT:  [[EVLM2:%.+]] = icmp ult <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>, [[NSPLAT2]]
 ; ALL-CONVERT-NEXT:  [[NEWM2:%.+]] = and <8 x i1> [[EVLM2]], %m
-; ALL-CONVERT-NEXT:  %r11 = call <8 x i32> @llvm.vp.merge.v8i32(<8 x i1> [[NEWM2]], <8 x i32> %i0, <8 x i32> %i1, i32 8)
-; ALL-CONVERT-NEXT:  %r12 = call <8 x i32> @llvm.vp.select.v8i32(<8 x i1> %m, <8 x i32> %i0, <8 x i32> %i1, i32 8)
+; ALL-CONVERT-NEXT:  %{{.+}} = select <8 x i1> [[NEWM2]], <8 x i32> %i0, <8 x i32> %i1
+; ALL-CONVERT:       %{{.+}} = select <8 x i1> %m, <8 x i32> %i0, <8 x i32> %i1
 ; ALL-CONVERT-NEXT:  ret void
 
 ; ALL-CONVERT: 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) {
@@ -244,8 +244,8 @@ define void @test_vp_cmp_v8(<8 x i32> %i0, <8 x i32> %i1, <8 x float> %f0, <8 x
 ; ALL-CONVERT:       %{{.*}} = shl <vscale x 4 x i32> %i0, %i1
 ; ALL-CONVERT:       [[EVLM5:%.+]] = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 %n)
 ; ALL-CONVERT:       [[NEWM5:%.+]] = and <vscale x 4 x i1> [[EVLM5]], %m
-; ALL-CONVERT:       %r11 = call <vscale x 4 x i32> @llvm.vp.merge.nxv4i32(<vscale x 4 x i1> [[NEWM5]], <vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, i32 %scalable_size{{.*}})
-; ALL-CONVERT:       %r12 = call <vscale x 4 x i32> @llvm.vp.select.nxv4i32(<vscale x 4 x i1> %m, <vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1, i32 %scalable_size{{.*}})
+; ALL-CONVERT:       %{{.*}} = select <vscale x 4 x i1> [[NEWM5]], <vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1
+; ALL-CONVERT:       %{{.*}} = select <vscale x 4 x i1> %m, <vscale x 4 x i32> %i0, <vscale x 4 x i32> %i1
 ; ALL-CONVERT-NEXT:  ret void
 
 ; Check that reductions use the correct neutral element for masked-off elements