[llvm] [RISCV] Enable tail folding by default (PR #151681)

[Luke Lau via llvm-commits]

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@@ -62,50 +62,10 @@ define i32 @any_of_reduction_used_in_blend_with_multiple_phis(ptr %src, i64 %N,
 ; CHECK-LABEL: define i32 @any_of_reduction_used_in_blend_with_multiple_phis(
 ; CHECK-SAME: ptr [[SRC:%.*]], i64 [[N:%.*]], i1 [[C_0:%.*]], i1 [[C_1:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
-; CHECK-NEXT:    [[TMP0:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT:    [[TMP1:%.*]] = mul nuw i64 [[TMP0]], 2
-; CHECK-NEXT:    [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[N]], [[TMP1]]
-; CHECK-NEXT:    br i1 [[MIN_ITERS_CHECK]], label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
-; CHECK:       [[VECTOR_PH]]:
-; CHECK-NEXT:    [[TMP2:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT:    [[TMP3:%.*]] = mul nuw i64 [[TMP2]], 2
-; CHECK-NEXT:    [[N_MOD_VF:%.*]] = urem i64 [[N]], [[TMP3]]
-; CHECK-NEXT:    [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
-; CHECK-NEXT:    [[TMP4:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT:    [[TMP5:%.*]] = mul nuw i64 [[TMP4]], 2
-; CHECK-NEXT:    [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <vscale x 2 x i1> poison, i1 [[C_1]], i64 0
-; CHECK-NEXT:    [[BROADCAST_SPLAT2:%.*]] = shufflevector <vscale x 2 x i1> [[BROADCAST_SPLATINSERT1]], <vscale x 2 x i1> poison, <vscale x 2 x i32> zeroinitializer
-; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 2 x i1> poison, i1 [[C_0]], i64 0
-; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 2 x i1> [[BROADCAST_SPLATINSERT]], <vscale x 2 x i1> poison, <vscale x 2 x i32> zeroinitializer
-; CHECK-NEXT:    [[TMP6:%.*]] = xor <vscale x 2 x i1> [[BROADCAST_SPLAT]], splat (i1 true)
-; CHECK-NEXT:    [[TMP7:%.*]] = xor <vscale x 2 x i1> [[BROADCAST_SPLAT2]], splat (i1 true)
-; CHECK-NEXT:    [[TMP8:%.*]] = select <vscale x 2 x i1> [[TMP6]], <vscale x 2 x i1> [[TMP7]], <vscale x 2 x i1> zeroinitializer
-; CHECK-NEXT:    [[BROADCAST_SPLATINSERT3:%.*]] = insertelement <vscale x 2 x ptr> poison, ptr [[SRC]], i64 0
-; CHECK-NEXT:    [[BROADCAST_SPLAT4:%.*]] = shufflevector <vscale x 2 x ptr> [[BROADCAST_SPLATINSERT3]], <vscale x 2 x ptr> poison, <vscale x 2 x i32> zeroinitializer
-; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
-; CHECK:       [[VECTOR_BODY]]:
-; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
-; CHECK-NEXT:    [[VEC_PHI:%.*]] = phi <vscale x 2 x i1> [ zeroinitializer, %[[VECTOR_PH]] ], [ [[PREDPHI:%.*]], %[[VECTOR_BODY]] ]
-; CHECK-NEXT:    [[WIDE_MASKED_GATHER:%.*]] = call <vscale x 2 x ptr> @llvm.masked.gather.nxv2p0.nxv2p0(<vscale x 2 x ptr> [[BROADCAST_SPLAT4]], i32 8, <vscale x 2 x i1> [[TMP8]], <vscale x 2 x ptr> poison)
-; CHECK-NEXT:    [[TMP9:%.*]] = icmp eq <vscale x 2 x ptr> [[WIDE_MASKED_GATHER]], zeroinitializer
-; CHECK-NEXT:    [[TMP10:%.*]] = or <vscale x 2 x i1> [[VEC_PHI]], [[TMP9]]
-; CHECK-NEXT:    [[PREDPHI]] = select <vscale x 2 x i1> [[TMP8]], <vscale x 2 x i1> [[TMP10]], <vscale x 2 x i1> [[VEC_PHI]]
-; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], [[TMP5]]
-; CHECK-NEXT:    [[TMP11:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
-; CHECK-NEXT:    br i1 [[TMP11]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
-; CHECK:       [[MIDDLE_BLOCK]]:
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lukel97 wrote:

Yeah, I've included a note about this in the PR description

https://github.com/llvm/llvm-project/pull/151681