LV]: consider scalable VF during deciding dead epilogue. #156724
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hassnaaHamdi
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@llvm/pr-subscribers-vectorizers @llvm/pr-subscribers-llvm-transforms Author: Hassnaa Hamdi (hassnaaHamdi) ChangesThis patch should be on top of #156723 Patch is 90.64 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/156724.diff 4 Files Affected:
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 3fbeef1211954..c73ebc1cfac35 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4411,8 +4411,21 @@ VectorizationFactor LoopVectorizationPlanner::selectEpilogueVectorizationFactor(
const SCEV *TC =
vputils::getSCEVExprForVPValue(getPlanFor(MainLoopVF).getTripCount(), SE);
assert(!isa<SCEVCouldNotCompute>(TC) && "Trip count SCEV must be computable");
+
+ // TODO: Maybe this could be removed when SCEV can evaluate expressions with
+ // 'vscale'.
+ // If TC is multiple of vscale, try to get estimated value:
+ if (match(TC, m_scev_Mul(m_SCEV(), m_SCEVVScale()))) {
+ std::optional<ElementCount> BestKnownTC =
+ getSmallBestKnownTC(PSE, OrigLoop);
+ if (BestKnownTC) {
+ unsigned EstimatedRuntimeTC =
+ estimateElementCount(*BestKnownTC, CM.getVScaleForTuning());
+ TC = SE.getConstant(TCType, EstimatedRuntimeTC);
+ }
+ }
RemainingIterations =
- SE.getURemExpr(TC, SE.getElementCount(TCType, MainLoopVF * IC));
+ SE.getURemExpr(TC, SE.getElementCount(TCType, EstimatedRuntimeVF * IC));
// No iterations left to process in the epilogue.
if (RemainingIterations->isZero())
@@ -4445,13 +4458,12 @@ VectorizationFactor LoopVectorizationPlanner::selectEpilogueVectorizationFactor(
// If NextVF is greater than the number of remaining iterations, the
// epilogue loop would be dead. Skip such factors.
- if (RemainingIterations && !NextVF.Width.isScalable()) {
- if (SE.isKnownPredicate(
- CmpInst::ICMP_UGT,
- SE.getConstant(TCType, NextVF.Width.getFixedValue()),
- RemainingIterations))
- continue;
- }
+ ElementCount EstimatedRuntimeNextVF = ElementCount::getFixed(
+ estimateElementCount(NextVF.Width, CM.getVScaleForTuning()));
+ if (SE.isKnownPredicate(CmpInst::ICMP_UGT,
+ SE.getElementCount(TCType, EstimatedRuntimeNextVF),
+ RemainingIterations))
+ continue;
if (Result.Width.isScalar() ||
isMoreProfitable(NextVF, Result, MaxTripCount, !CM.foldTailByMasking()))
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/interleave-with-gaps.ll b/llvm/test/Transforms/LoopVectorize/AArch64/interleave-with-gaps.ll
index 1c78c5e6f2ce8..aca3c5c4ce39d 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/interleave-with-gaps.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/interleave-with-gaps.ll
@@ -9,13 +9,8 @@ target triple = "aarch64-linux-gnu"
define i64 @vector_loop_with_remaining_iterations(ptr %src, ptr noalias %dst, i32 %x) #0 {
; CHECK-LABEL: define i64 @vector_loop_with_remaining_iterations(
; CHECK-SAME: ptr [[SRC:%.*]], ptr noalias [[DST:%.*]], i32 [[X:%.*]]) #[[ATTR0:[0-9]+]] {
-; CHECK-NEXT: [[ITER_CHECK:.*]]:
-; CHECK-NEXT: [[TMP0:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP1:%.*]] = shl nuw i64 [[TMP0]], 1
-; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ule i64 17, [[TMP1]]
-; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label %[[VEC_EPILOG_SCALAR_PH:.*]], label %[[VECTOR_MAIN_LOOP_ITER_CHECK:.*]]
-; CHECK: [[VECTOR_MAIN_LOOP_ITER_CHECK]]:
-; CHECK-NEXT: br i1 false, label %[[VEC_EPILOG_PH:.*]], label %[[VECTOR_PH:.*]]
+; CHECK-NEXT: [[ENTRY:.*]]:
+; CHECK-NEXT: br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <16 x i32> poison, i32 [[X]], i64 0
; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <16 x i32> [[BROADCAST_SPLATINSERT]], <16 x i32> poison, <16 x i32> zeroinitializer
@@ -39,60 +34,14 @@ define i64 @vector_loop_with_remaining_iterations(ptr %src, ptr noalias %dst, i3
; CHECK-NEXT: br i1 [[TMP12]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
; CHECK: [[MIDDLE_BLOCK]]:
; CHECK-NEXT: [[TMP13:%.*]] = call i64 @llvm.vector.reduce.or.v16i64(<16 x i64> [[TMP11]])
-; CHECK-NEXT: br label %[[VEC_EPILOG_ITER_CHECK:.*]]
-; CHECK: [[VEC_EPILOG_ITER_CHECK]]:
-; CHECK-NEXT: [[TMP14:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP15:%.*]] = shl nuw i64 [[TMP14]], 1
-; CHECK-NEXT: [[MIN_EPILOG_ITERS_CHECK:%.*]] = icmp ule i64 1, [[TMP15]]
-; CHECK-NEXT: br i1 [[MIN_EPILOG_ITERS_CHECK]], label %[[VEC_EPILOG_SCALAR_PH]], label %[[VEC_EPILOG_PH]]
-; CHECK: [[VEC_EPILOG_PH]]:
-; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 16, %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
-; CHECK-NEXT: [[BC_MERGE_RDX:%.*]] = phi i64 [ [[TMP13]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
-; CHECK-NEXT: [[TMP16:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP17:%.*]] = mul nuw i64 [[TMP16]], 2
-; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 17, [[TMP17]]
-; CHECK-NEXT: [[TMP18:%.*]] = icmp eq i64 [[N_MOD_VF]], 0
-; CHECK-NEXT: [[TMP19:%.*]] = select i1 [[TMP18]], i64 [[TMP17]], i64 [[N_MOD_VF]]
-; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 17, [[TMP19]]
-; CHECK-NEXT: [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <vscale x 2 x i32> poison, i32 [[X]], i64 0
-; CHECK-NEXT: [[BROADCAST_SPLAT2:%.*]] = shufflevector <vscale x 2 x i32> [[BROADCAST_SPLATINSERT1]], <vscale x 2 x i32> poison, <vscale x 2 x i32> zeroinitializer
-; CHECK-NEXT: [[TMP22:%.*]] = insertelement <vscale x 2 x i64> zeroinitializer, i64 [[BC_MERGE_RDX]], i32 0
-; CHECK-NEXT: [[TMP24:%.*]] = call <vscale x 2 x i32> @llvm.abs.nxv2i32(<vscale x 2 x i32> [[BROADCAST_SPLAT2]], i1 false)
-; CHECK-NEXT: [[TMP25:%.*]] = call <vscale x 2 x i64> @llvm.stepvector.nxv2i64()
-; CHECK-NEXT: [[BROADCAST_SPLATINSERT3:%.*]] = insertelement <vscale x 2 x i64> poison, i64 [[BC_RESUME_VAL]], i64 0
-; CHECK-NEXT: [[BROADCAST_SPLAT4:%.*]] = shufflevector <vscale x 2 x i64> [[BROADCAST_SPLATINSERT3]], <vscale x 2 x i64> poison, <vscale x 2 x i32> zeroinitializer
-; CHECK-NEXT: [[TMP26:%.*]] = mul <vscale x 2 x i64> [[TMP25]], splat (i64 1)
-; CHECK-NEXT: [[INDUCTION:%.*]] = add <vscale x 2 x i64> [[BROADCAST_SPLAT4]], [[TMP26]]
-; CHECK-NEXT: [[BROADCAST_SPLATINSERT5:%.*]] = insertelement <vscale x 2 x i64> poison, i64 [[TMP17]], i64 0
-; CHECK-NEXT: [[BROADCAST_SPLAT6:%.*]] = shufflevector <vscale x 2 x i64> [[BROADCAST_SPLATINSERT5]], <vscale x 2 x i64> poison, <vscale x 2 x i32> zeroinitializer
-; CHECK-NEXT: br label %[[VEC_EPILOG_VECTOR_BODY:.*]]
-; CHECK: [[VEC_EPILOG_VECTOR_BODY]]:
-; CHECK-NEXT: [[INDEX7:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[VEC_EPILOG_PH]] ], [ [[INDEX_NEXT9:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
-; CHECK-NEXT: [[VEC_IND:%.*]] = phi <vscale x 2 x i64> [ [[INDUCTION]], %[[VEC_EPILOG_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
-; CHECK-NEXT: [[VEC_PHI8:%.*]] = phi <vscale x 2 x i64> [ [[TMP22]], %[[VEC_EPILOG_PH]] ], [ [[TMP35:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
-; CHECK-NEXT: [[TMP28:%.*]] = getelementptr { [4 x i8] }, ptr [[SRC]], <vscale x 2 x i64> [[VEC_IND]], i32 0, i64 3
-; CHECK-NEXT: [[WIDE_MASKED_GATHER:%.*]] = call <vscale x 2 x i8> @llvm.masked.gather.nxv2i8.nxv2p0(<vscale x 2 x ptr> [[TMP28]], i32 1, <vscale x 2 x i1> splat (i1 true), <vscale x 2 x i8> poison)
-; CHECK-NEXT: [[TMP29:%.*]] = zext <vscale x 2 x i8> [[WIDE_MASKED_GATHER]] to <vscale x 2 x i32>
-; CHECK-NEXT: [[TMP30:%.*]] = call <vscale x 2 x i32> @llvm.umin.nxv2i32(<vscale x 2 x i32> [[TMP24]], <vscale x 2 x i32> [[TMP29]])
-; CHECK-NEXT: [[TMP31:%.*]] = call <vscale x 2 x i32> @llvm.umin.nxv2i32(<vscale x 2 x i32> [[TMP24]], <vscale x 2 x i32> [[TMP30]])
-; CHECK-NEXT: [[TMP32:%.*]] = getelementptr inbounds i8, ptr [[DST]], i64 [[INDEX7]]
-; CHECK-NEXT: store <vscale x 2 x i8> zeroinitializer, ptr [[TMP32]], align 1
-; CHECK-NEXT: [[TMP34:%.*]] = zext <vscale x 2 x i32> [[TMP31]] to <vscale x 2 x i64>
-; CHECK-NEXT: [[TMP35]] = or <vscale x 2 x i64> [[VEC_PHI8]], [[TMP34]]
-; CHECK-NEXT: [[INDEX_NEXT9]] = add nuw i64 [[INDEX7]], [[TMP17]]
-; CHECK-NEXT: [[VEC_IND_NEXT]] = add <vscale x 2 x i64> [[VEC_IND]], [[BROADCAST_SPLAT6]]
-; CHECK-NEXT: [[TMP36:%.*]] = icmp eq i64 [[INDEX_NEXT9]], [[N_VEC]]
-; CHECK-NEXT: br i1 [[TMP36]], label %[[VEC_EPILOG_MIDDLE_BLOCK:.*]], label %[[VEC_EPILOG_VECTOR_BODY]], !llvm.loop [[LOOP3:![0-9]+]]
-; CHECK: [[VEC_EPILOG_MIDDLE_BLOCK]]:
-; CHECK-NEXT: [[TMP37:%.*]] = call i64 @llvm.vector.reduce.or.nxv2i64(<vscale x 2 x i64> [[TMP35]])
-; CHECK-NEXT: br label %[[VEC_EPILOG_SCALAR_PH]]
-; CHECK: [[VEC_EPILOG_SCALAR_PH]]:
-; CHECK-NEXT: [[BC_RESUME_VAL10:%.*]] = phi i64 [ [[N_VEC]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ 16, %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
-; CHECK-NEXT: [[BC_MERGE_RDX11:%.*]] = phi i64 [ [[TMP37]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ [[TMP13]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
+; CHECK-NEXT: br label %[[SCALAR_PH]]
+; CHECK: [[SCALAR_PH]]:
+; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 16, %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT: [[BC_MERGE_RDX:%.*]] = phi i64 [ [[TMP13]], %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
; CHECK-NEXT: br label %[[LOOP:.*]]
; CHECK: [[LOOP]]:
-; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL10]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
-; CHECK-NEXT: [[RED:%.*]] = phi i64 [ [[BC_MERGE_RDX11]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[RED_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[RED:%.*]] = phi i64 [ [[BC_MERGE_RDX]], %[[SCALAR_PH]] ], [ [[RED_NEXT:%.*]], %[[LOOP]] ]
; CHECK-NEXT: [[GEP_SRC_I_I:%.*]] = getelementptr { [4 x i8] }, ptr [[SRC]], i64 [[IV]], i32 0, i64 3
; CHECK-NEXT: [[L:%.*]] = load i8, ptr [[GEP_SRC_I_I]], align 1
; CHECK-NEXT: [[L_EXT:%.*]] = zext i8 [[L]] to i32
@@ -106,7 +55,7 @@ define i64 @vector_loop_with_remaining_iterations(ptr %src, ptr noalias %dst, i3
; CHECK-NEXT: [[RED_NEXT]] = or i64 [[RED]], [[MIN_EXT]]
; CHECK-NEXT: [[IV_NEXT]] = add i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND_NOT_I_I:%.*]] = icmp eq i64 [[IV_NEXT]], 17
-; CHECK-NEXT: br i1 [[EXITCOND_NOT_I_I]], label %[[EXIT:.*]], label %[[LOOP]], !llvm.loop [[LOOP4:![0-9]+]]
+; CHECK-NEXT: br i1 [[EXITCOND_NOT_I_I]], label %[[EXIT:.*]], label %[[LOOP]], !llvm.loop [[LOOP3:![0-9]+]]
; CHECK: [[EXIT]]:
; CHECK-NEXT: [[RED_NEXT_LCSSA:%.*]] = phi i64 [ [[RED_NEXT]], %[[LOOP]] ]
; CHECK-NEXT: ret i64 [[RED_NEXT_LCSSA]]
@@ -142,13 +91,8 @@ exit:
define i64 @main_vector_loop_fixed_with_no_remaining_iterations(ptr %src, ptr noalias %dst, i32 %x) #0 {
; CHECK-LABEL: define i64 @main_vector_loop_fixed_with_no_remaining_iterations(
; CHECK-SAME: ptr [[SRC:%.*]], ptr noalias [[DST:%.*]], i32 [[X:%.*]]) #[[ATTR0]] {
-; CHECK-NEXT: [[ITER_CHECK:.*]]:
-; CHECK-NEXT: [[TMP0:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP1:%.*]] = shl nuw i64 [[TMP0]], 1
-; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ule i64 17, [[TMP1]]
-; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label %[[VEC_EPILOG_SCALAR_PH:.*]], label %[[VECTOR_MAIN_LOOP_ITER_CHECK:.*]]
-; CHECK: [[VECTOR_MAIN_LOOP_ITER_CHECK]]:
-; CHECK-NEXT: br i1 false, label %[[VEC_EPILOG_PH:.*]], label %[[VECTOR_PH:.*]]
+; CHECK-NEXT: [[ENTRY:.*]]:
+; CHECK-NEXT: br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <16 x i32> poison, i32 [[X]], i64 0
; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <16 x i32> [[BROADCAST_SPLATINSERT]], <16 x i32> poison, <16 x i32> zeroinitializer
@@ -169,63 +113,17 @@ define i64 @main_vector_loop_fixed_with_no_remaining_iterations(ptr %src, ptr no
; CHECK-NEXT: [[TMP11]] = or <16 x i64> [[VEC_PHI]], [[TMP10]]
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 16
; CHECK-NEXT: [[TMP12:%.*]] = icmp eq i64 [[INDEX_NEXT]], 16
-; CHECK-NEXT: br i1 [[TMP12]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP5:![0-9]+]]
+; CHECK-NEXT: br i1 [[TMP12]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
; CHECK: [[MIDDLE_BLOCK]]:
; CHECK-NEXT: [[TMP13:%.*]] = call i64 @llvm.vector.reduce.or.v16i64(<16 x i64> [[TMP11]])
-; CHECK-NEXT: br label %[[VEC_EPILOG_ITER_CHECK:.*]]
-; CHECK: [[VEC_EPILOG_ITER_CHECK]]:
-; CHECK-NEXT: [[TMP14:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP15:%.*]] = shl nuw i64 [[TMP14]], 1
-; CHECK-NEXT: [[MIN_EPILOG_ITERS_CHECK:%.*]] = icmp ule i64 1, [[TMP15]]
-; CHECK-NEXT: br i1 [[MIN_EPILOG_ITERS_CHECK]], label %[[VEC_EPILOG_SCALAR_PH]], label %[[VEC_EPILOG_PH]]
-; CHECK: [[VEC_EPILOG_PH]]:
-; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 16, %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
-; CHECK-NEXT: [[BC_MERGE_RDX:%.*]] = phi i64 [ [[TMP13]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
-; CHECK-NEXT: [[TMP16:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP17:%.*]] = mul nuw i64 [[TMP16]], 2
-; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 17, [[TMP17]]
-; CHECK-NEXT: [[TMP18:%.*]] = icmp eq i64 [[N_MOD_VF]], 0
-; CHECK-NEXT: [[TMP19:%.*]] = select i1 [[TMP18]], i64 [[TMP17]], i64 [[N_MOD_VF]]
-; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 17, [[TMP19]]
-; CHECK-NEXT: [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <vscale x 2 x i32> poison, i32 [[X]], i64 0
-; CHECK-NEXT: [[BROADCAST_SPLAT2:%.*]] = shufflevector <vscale x 2 x i32> [[BROADCAST_SPLATINSERT1]], <vscale x 2 x i32> poison, <vscale x 2 x i32> zeroinitializer
-; CHECK-NEXT: [[TMP22:%.*]] = insertelement <vscale x 2 x i64> zeroinitializer, i64 [[BC_MERGE_RDX]], i32 0
-; CHECK-NEXT: [[TMP24:%.*]] = call <vscale x 2 x i32> @llvm.abs.nxv2i32(<vscale x 2 x i32> [[BROADCAST_SPLAT2]], i1 false)
-; CHECK-NEXT: [[TMP25:%.*]] = call <vscale x 2 x i64> @llvm.stepvector.nxv2i64()
-; CHECK-NEXT: [[BROADCAST_SPLATINSERT3:%.*]] = insertelement <vscale x 2 x i64> poison, i64 [[BC_RESUME_VAL]], i64 0
-; CHECK-NEXT: [[BROADCAST_SPLAT4:%.*]] = shufflevector <vscale x 2 x i64> [[BROADCAST_SPLATINSERT3]], <vscale x 2 x i64> poison, <vscale x 2 x i32> zeroinitializer
-; CHECK-NEXT: [[TMP38:%.*]] = mul <vscale x 2 x i64> [[TMP25]], splat (i64 1)
-; CHECK-NEXT: [[INDUCTION:%.*]] = add <vscale x 2 x i64> [[BROADCAST_SPLAT4]], [[TMP38]]
-; CHECK-NEXT: [[BROADCAST_SPLATINSERT5:%.*]] = insertelement <vscale x 2 x i64> poison, i64 [[TMP17]], i64 0
-; CHECK-NEXT: [[BROADCAST_SPLAT6:%.*]] = shufflevector <vscale x 2 x i64> [[BROADCAST_SPLATINSERT5]], <vscale x 2 x i64> poison, <vscale x 2 x i32> zeroinitializer
-; CHECK-NEXT: br label %[[VEC_EPILOG_VECTOR_BODY:.*]]
-; CHECK: [[VEC_EPILOG_VECTOR_BODY]]:
-; CHECK-NEXT: [[INDEX7:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[VEC_EPILOG_PH]] ], [ [[INDEX_NEXT9:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
-; CHECK-NEXT: [[VEC_IND:%.*]] = phi <vscale x 2 x i64> [ [[INDUCTION]], %[[VEC_EPILOG_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
-; CHECK-NEXT: [[VEC_PHI8:%.*]] = phi <vscale x 2 x i64> [ [[TMP22]], %[[VEC_EPILOG_PH]] ], [ [[TMP35:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
-; CHECK-NEXT: [[TMP28:%.*]] = getelementptr { [4 x i8] }, ptr [[SRC]], <vscale x 2 x i64> [[VEC_IND]], i32 0, i64 3
-; CHECK-NEXT: [[WIDE_MASKED_GATHER:%.*]] = call <vscale x 2 x i8> @llvm.masked.gather.nxv2i8.nxv2p0(<vscale x 2 x ptr> [[TMP28]], i32 1, <vscale x 2 x i1> splat (i1 true), <vscale x 2 x i8> poison)
-; CHECK-NEXT: [[TMP29:%.*]] = zext <vscale x 2 x i8> [[WIDE_MASKED_GATHER]] to <vscale x 2 x i32>
-; CHECK-NEXT: [[TMP30:%.*]] = call <vscale x 2 x i32> @llvm.umin.nxv2i32(<vscale x 2 x i32> [[TMP24]], <vscale x 2 x i32> [[TMP29]])
-; CHECK-NEXT: [[TMP31:%.*]] = call <vscale x 2 x i32> @llvm.umin.nxv2i32(<vscale x 2 x i32> [[TMP24]], <vscale x 2 x i32> [[TMP30]])
-; CHECK-NEXT: [[TMP32:%.*]] = getelementptr inbounds i8, ptr [[DST]], i64 [[INDEX7]]
-; CHECK-NEXT: store <vscale x 2 x i8> zeroinitializer, ptr [[TMP32]], align 1
-; CHECK-NEXT: [[TMP34:%.*]] = zext <vscale x 2 x i32> [[TMP31]] to <vscale x 2 x i64>
-; CHECK-NEXT: [[TMP35]] = or <vscale x 2 x i64> [[VEC_PHI8]], [[TMP34]]
-; CHECK-NEXT: [[INDEX_NEXT9]] = add nuw i64 [[INDEX7]], [[TMP17]]
-; CHECK-NEXT: [[VEC_IND_NEXT]] = add <vscale x 2 x i64> [[VEC_IND]], [[BROADCAST_SPLAT6]]
-; CHECK-NEXT: [[TMP36:%.*]] = icmp eq i64 [[INDEX_NEXT9]], [[N_VEC]]
-; CHECK-NEXT: br i1 [[TMP36]], label %[[VEC_EPILOG_MIDDLE_BLOCK:.*]], label %[[VEC_EPILOG_VECTOR_BODY]], !llvm.loop [[LOOP6:![0-9]+]]
-; CHECK: [[VEC_EPILOG_MIDDLE_BLOCK]]:
-; CHECK-NEXT: [[TMP37:%.*]] = call i64 @llvm.vector.reduce.or.nxv2i64(<vscale x 2 x i64> [[TMP35]])
-; CHECK-NEXT: br label %[[VEC_EPILOG_SCALAR_PH]]
-; CHECK: [[VEC_EPILOG_SCALAR_PH]]:
-; CHECK-NEXT: [[BC_RESUME_VAL10:%.*]] = phi i64 [ [[N_VEC]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ 16, %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
-; CHECK-NEXT: [[BC_MERGE_RDX11:%.*]] = phi i64 [ [[TMP37]], %[[VEC_EPILOG_MIDDLE_BLOCK]] ], [ [[TMP13]], %[[VEC_EPILOG_ITER_CHECK]] ], [ 0, %[[ITER_CHECK]] ]
+; CHECK-NEXT: br label %[[SCALAR_PH]]
+; CHECK: [[SCALAR_PH]]:
+; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 16, %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT: [[BC_MERGE_RDX:%.*]] = phi i64 [ [[TMP13]], %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
; CHECK-NEXT: br label %[[LOOP:.*]]
; CHECK: [[LOOP]]:
-; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL10]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
-; CHECK-NEXT: [[RED:%.*]] = phi i64 [ [[BC_MERGE_RDX11]], %[[VEC_EPILOG_SCALAR_PH]] ], [ [[RED_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[RED:%.*]] = phi i64 [ [[BC_MERGE_RDX]], %[[SCALAR_PH]] ], [ [[RED_NEXT:%.*]], %[[LOOP]] ]
; CHECK-NEXT: [[GEP_SRC_I_I:%.*]] = getelementptr { [4 x i8] }, ptr [[SRC]], i64 [[IV]], i32 0, i64 3
; CHECK-NEXT: [[L:%.*]] = load i8, ptr [[GEP_SRC_I_I]], align 1
; CHECK-NEXT: [[L_EXT:%.*]] = zext i8 [[L]] to i32
@@ -239,7 +137,7 @@ define i64 @main_vector_loop_fixed_with_no_remaining_iterations(ptr %src, ptr no
; CHECK-NEXT: [[RED_NEXT]] = or i64 [[RED]], [[MIN_EXT]]
; CHECK-NEXT: [[IV_NEXT]] = add i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND_NOT_I_I:%.*]] = icmp eq i64 [[IV_NEXT]], 17
-; CHECK-NEXT: br i1 [[EXITCOND_NOT_I_I]], label %[[EXIT:.*]], label %[[LOOP]], !llvm.loop [[LOOP7:![0-9]+]]
+; CHECK-NEXT: br i1 [[EXITCOND_NOT_I_I]], label %[[EXIT:.*]], label %[[LOOP]], !llvm.loop [[LOOP5:![0-9]+]]
; CHECK: [[EXIT]]:
; CHECK-NEXT: [[RED_NEXT_LCSSA:%.*]] = phi i64 [ [[RED_NEXT]], %[[LOOP]] ]
; CHECK-NEXT: ret i64 [[RED_NEXT_LCSSA]]
@@ -312,7 +210,7 @@ define void @main_vector_loop_fixed_single_vector_iteration_with_runtime_checks(
; CHECK-NEXT: store i64 0, ptr [[L]], align 8
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
; CHECK-NEXT: [[TMP14:%.*]] = icmp eq i64 [[INDEX_NEXT]], 4
-; CHECK-NEXT: br i1 [[TMP14]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP8:![0-9]+]]
+; CHECK-NEXT: br i1 [[TMP14]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP6:![0-9]+]]
; CHECK: [[MIDDLE_BLOCK]]:
; CHECK-NEXT: br label %[[SCALAR_PH]]
; CHECK: [[SCALAR_PH]]:
@@ -337,7 +235,7 @@ define void @main_vector_loop_fixed_single_vector_iteration_with_runtime_checks(
; CHECK-NEXT: store i64 0, ptr [[L]], align 8
; CHECK-NEXT: [[IV_NEXT]] = add i64 [[IV1]], 2
; CHECK-NEXT: [[EC:%.*]] = icmp ult i64 [[IV1]], 14
-; CHECK-NEXT: br i1 [[EC]], label %[[LOOP]], label %[[EXIT:.*]], !llvm.loop [[LOOP10:![0-9]+]]
+; CHECK-NEXT: br i1 [[EC]], label %[[LOOP]], label %[[EXIT:.*]], !llvm.loop [[LOOP8:![0-9]+]]
; CHECK: [[EXIT]]:
; CHECK-NEXT: ret void
;
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/store-costs-sve.ll b/llvm/test/Transforms/LoopVectorize/AArch64/store-costs-sve.ll
index 4055d016...
[truncated]
|
hassnaaHamdi
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You can test this locally with the following command:git-clang-format --diff origin/main HEAD --extensions cpp -- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp --diff_from_common_commit
View the diff from clang-format here.diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 5be66fd49..51600e55a 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4409,7 +4409,9 @@ VectorizationFactor LoopVectorizationPlanner::selectEpilogueVectorizationFactor(
}
// Check if the RemainingIterations is scalable.
const SCEV *KnownMinRemIter = nullptr, *EstimatedRemIter = nullptr;
- bool ScalableRemIter = match(RemainingIterations, m_scev_c_Mul(m_SCEV(KnownMinRemIter), m_SCEVVScale()));
+ bool ScalableRemIter =
+ match(RemainingIterations,
+ m_scev_c_Mul(m_SCEV(KnownMinRemIter), m_SCEVVScale()));
if (ScalableRemIter)
EstimatedRemIter = SE.getMulExpr(
KnownMinRemIter,
@@ -4434,8 +4436,8 @@ VectorizationFactor LoopVectorizationPlanner::selectEpilogueVectorizationFactor(
// epilogue loop would be dead. Skip such factors.
if (ScalableRemIter == NextVF.Width.isScalable()) {
if (SE.isKnownPredicate(CmpInst::ICMP_UGT,
- SE.getElementCount(TCType, NextVF.Width),
- RemainingIterations))
+ SE.getElementCount(TCType, NextVF.Width),
+ RemainingIterations))
continue;
}
// Handle the case where NextVF and RemainingIterations are in different
@@ -4443,9 +4445,10 @@ VectorizationFactor LoopVectorizationPlanner::selectEpilogueVectorizationFactor(
else if (NextVF.Width.isScalable()) {
ElementCount EstimatedRuntimeNextVF = ElementCount::getFixed(
estimateElementCount(NextVF.Width, CM.getVScaleForTuning()));
- if (SE.isKnownPredicate(CmpInst::ICMP_UGT,
- SE.getElementCount(TCType, EstimatedRuntimeNextVF),
- RemainingIterations))
+ if (SE.isKnownPredicate(
+ CmpInst::ICMP_UGT,
+ SE.getElementCount(TCType, EstimatedRuntimeNextVF),
+ RemainingIterations))
continue;
} else {
if (SE.isKnownPredicate(CmpInst::ICMP_UGT,
|
david-arm
reviewed
Nov 4, 2025
| LLVM_DEBUG(dbgs() << "LEV: Maximum Trip Count for Epilogue: " | ||
| << MaxTripCount << "\n"); | ||
| } | ||
| // Check if the RemainingIterations is scalable. |
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Do we actually need this code? Unless I've missed something the only way RemainingIterations can be scalable is if both ScalableTC==true and MainLoopVF.isScalable()==true. Can't you just write
bool ScalableRemIter = ScalableTC && MainLoopVF.isScalable();
For all other calculations we are either operating on fixed-width only or we have used estimates for scalable versions.
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Yeah we still need this code.
We need to calculate the EstimatedRemIter to compare it against the fixed-width VFs.
The dependency on the fact that ScalableTC==true and MainLoopVF.isScalable()==true doesn't work for cases where SCEV can't get the KnownMinRemIter to calculate EstimatedRemIter, cases like when the RemainingIter is just vscale.
I could add a TODO here to simplify it as your suggestion, when SCEV can be able to handle scale_based expressions that are not in the standard form of: var x vscale
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OK so if both ScalableTC==true and MainLoopVF.isScalable()==true then we know RemainingIterations must be a multiple of vscale. If we cannot calculate EstimatedRemIter because RemainingIterations!=var x vscale then in the new code below we will end up comparing a fixed value with vscale.
When RemainingIterations isn't in the form var x vscale what does the expression look like? If it's just RemainingIterations=vscale then presumably we can support that fairly easily here too?
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Yes, it's just vscale, it could be handled by doing this:
const SCEV *KnownMinRemIter = SE->getOne(TCType), *EstimatedRemIter = nullptr;
bool ScalableRemIter =
match(RemainingIterations, m_scev_c_Mul(m_SCEV(KnownMinRemIter), m_SCEVVScale())) || match(RemainingIterations, m_SCEVVScale());
But I chose not to do that because that is a handling for a single case that SCEV can't handle, not generic handling for scale-based complex forms that SCEV can't handle.
But also I don't have strong opinion here, what do you think ?
| RemainingIterations)) | ||
| continue; | ||
| } else { | ||
| if (SE.isKnownPredicate(CmpInst::ICMP_UGT, |
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I think you can combine the if with the else, i.e.
} else if (SE.isKnown...)
continue;
| SE.getConstant(TCType, NextVF.Width.getFixedValue()), | ||
| RemainingIterations)) | ||
| if (ScalableRemIter == NextVF.Width.isScalable()) { | ||
| if (SE.isKnownPredicate(CmpInst::ICMP_UGT, |
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Given that you're asking the same thing each time, is it worth creating a small lambda function to do the work? For example,
auto skipNextVF = [&] (ElementCount VF) -> bool {
return SE.isKnownPredicate(...);
};
and then calling this lambda function each time?
| ; CHECK-NEXT: br i1 [[TMP12]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]] | ||
| ; CHECK: [[MIDDLE_BLOCK]]: | ||
| ; CHECK-NEXT: [[TMP13:%.*]] = call i64 @llvm.vector.reduce.or.v16i64(<16 x i64> [[TMP11]]) | ||
| ; CHECK-NEXT: br label %[[VEC_EPILOG_ITER_CHECK:.*]] |
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I think these changes can be reverted.
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This patch should be on top of #156723