tail-folding-counting-down.ll
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; RUN: opt < %s -loop-vectorize -S | FileCheck %s --check-prefixes=COMMON,DEFAULT
; RUN: opt < %s -loop-vectorize -tail-predication=enabled -prefer-predicate-over-epilogue=predicate-dont-vectorize -S | FileCheck %s --check-prefixes=COMMON,CHECK-TF,CHECK-PREFER
; RUN: opt < %s -loop-vectorize -tail-predication=enabled -prefer-predicate-over-epilogue=predicate-else-scalar-epilogue -S | FileCheck %s --check-prefixes=COMMON,CHECK-TF,CHECK-PREFER
; RUN: opt < %s -loop-vectorize -tail-predication=enabled -S | FileCheck %s --check-prefixes=COMMON,CHECK-TF,CHECK-ENABLE-TP
target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "thumbv8.1m.main-arm-unknown-eabihf"
; This IR corresponds to this type of C-code:
;
; void f(char *a, char *b, char *c, int N) {
; while (N-- > 0)
; *c++ = *a++ + *b++;
; }
;
define dso_local void @sgt_loopguard(i8* noalias nocapture readonly %a, i8* noalias nocapture readonly %b, i8* noalias nocapture %c, i32 %N) local_unnamed_addr #0 {
; COMMON-LABEL: @sgt_loopguard(
; COMMON: vector.body:
; CHECK-TF: %[[VIVELEM0:.*]] = extractelement <16 x i32> %vec.iv, i32 0
; CHECK-TF: %active.lane.mask = call <16 x i1> @llvm.get.active.lane.mask.v16i1.i32(i32 %[[VIVELEM0]], i32 %N)
; CHECK-TF: llvm.masked.load.v16i8.p0v16i8(<16 x i8>* %{{.*}}, i32 1, <16 x i1> %active.lane.mask
; CHECK-TF: llvm.masked.load.v16i8.p0v16i8(<16 x i8>* %{{.*}}, i32 1, <16 x i1> %active.lane.mask
; CHECK-TF: llvm.masked.store.v16i8.p0v16i8(<16 x i8> %{{.*}}, <16 x i8>* %{{.*}}, i32 1, <16 x i1> %active.lane.mask)
entry:
%cmp5 = icmp sgt i32 %N, 0
br i1 %cmp5, label %while.body.preheader, label %while.end
while.body.preheader:
br label %while.body
while.body:
%N.addr.09 = phi i32 [ %dec, %while.body ], [ %N, %while.body.preheader ]
%c.addr.08 = phi i8* [ %incdec.ptr4, %while.body ], [ %c, %while.body.preheader ]
%b.addr.07 = phi i8* [ %incdec.ptr1, %while.body ], [ %b, %while.body.preheader ]
%a.addr.06 = phi i8* [ %incdec.ptr, %while.body ], [ %a, %while.body.preheader ]
%dec = add nsw i32 %N.addr.09, -1
%incdec.ptr = getelementptr inbounds i8, i8* %a.addr.06, i32 1
%0 = load i8, i8* %a.addr.06, align 1
%incdec.ptr1 = getelementptr inbounds i8, i8* %b.addr.07, i32 1
%1 = load i8, i8* %b.addr.07, align 1
%add = add i8 %1, %0
%incdec.ptr4 = getelementptr inbounds i8, i8* %c.addr.08, i32 1
store i8 %add, i8* %c.addr.08, align 1
%cmp = icmp sgt i32 %N.addr.09, 1
br i1 %cmp, label %while.body, label %while.end.loopexit
while.end.loopexit:
br label %while.end
while.end:
ret void
}
; No loop-guard: we need one for this to be valid.
;
define dso_local void @sgt_no_loopguard(i8* noalias nocapture readonly %a, i8* noalias nocapture readonly %b, i8* noalias nocapture %c, i32 %N) local_unnamed_addr #0 {
; COMMON-LABEL: @sgt_no_loopguard(
; COMMON: vector.body:
; CHECK-TF: masked.load
; CHECK-TF: masked.load
; CHECK-TF: masked.store
entry:
br label %while.body
while.body:
%N.addr.09 = phi i32 [ %dec, %while.body ], [ %N, %entry ]
%c.addr.08 = phi i8* [ %incdec.ptr4, %while.body ], [ %c, %entry ]
%b.addr.07 = phi i8* [ %incdec.ptr1, %while.body ], [ %b, %entry ]
%a.addr.06 = phi i8* [ %incdec.ptr, %while.body ], [ %a, %entry ]
%dec = add nsw i32 %N.addr.09, -1
%incdec.ptr = getelementptr inbounds i8, i8* %a.addr.06, i32 1
%0 = load i8, i8* %a.addr.06, align 1
%incdec.ptr1 = getelementptr inbounds i8, i8* %b.addr.07, i32 1
%1 = load i8, i8* %b.addr.07, align 1
%add = add i8 %1, %0
%incdec.ptr4 = getelementptr inbounds i8, i8* %c.addr.08, i32 1
store i8 %add, i8* %c.addr.08, align 1
%cmp = icmp sgt i32 %N.addr.09, 1
br i1 %cmp, label %while.body, label %while.end.loopexit
while.end.loopexit:
br label %while.end
while.end:
ret void
}
define dso_local void @sgt_extra_use_cmp(i8* noalias nocapture readonly %a, i8* noalias nocapture readonly %b, i8* noalias nocapture %c, i32 %N) local_unnamed_addr #0 {
; COMMON-LABEL: @sgt_extra_use_cmp(
; COMMON: vector.body:
; CHECK-TF: masked.load
; CHECK-TF: masked.load
; CHECK-TF: masked.store
entry:
br label %while.body
while.body:
%N.addr.09 = phi i32 [ %dec, %while.body ], [ %N, %entry ]
%c.addr.08 = phi i8* [ %incdec.ptr4, %while.body ], [ %c, %entry ]
%b.addr.07 = phi i8* [ %incdec.ptr1, %while.body ], [ %b, %entry ]
%a.addr.06 = phi i8* [ %incdec.ptr, %while.body ], [ %a, %entry ]
%dec = add nsw i32 %N.addr.09, -1
%incdec.ptr = getelementptr inbounds i8, i8* %a.addr.06, i32 1
%0 = load i8, i8* %a.addr.06, align 1
%incdec.ptr1 = getelementptr inbounds i8, i8* %b.addr.07, i32 1
%1 = load i8, i8* %b.addr.07, align 1
%add = add i8 %1, %0
%incdec.ptr4 = getelementptr inbounds i8, i8* %c.addr.08, i32 1
store i8 %add, i8* %c.addr.08, align 1
%cmp = icmp sgt i32 %N.addr.09, 1
%select = select i1 %cmp, i8 %0, i8 %1
br i1 %cmp, label %while.body, label %while.end.loopexit
while.end.loopexit:
br label %while.end
while.end:
ret void
}
define dso_local void @sgt_const_tripcount(i8* noalias nocapture readonly %a, i8* noalias nocapture readonly %b, i8* noalias nocapture %c, i32 %N) local_unnamed_addr #0 {
; COMMON-LABEL: @sgt_const_tripcount(
; COMMON: vector.body:
; CHECK-TF: masked.load
; CHECK-TF: masked.load
; CHECK-TF: masked.store
entry:
%cmp5 = icmp sgt i32 %N, 0
br i1 %cmp5, label %while.body.preheader, label %while.end
while.body.preheader:
br label %while.body
while.body:
%N.addr.09 = phi i32 [ %dec, %while.body ], [ 2049, %while.body.preheader ]
%c.addr.08 = phi i8* [ %incdec.ptr4, %while.body ], [ %c, %while.body.preheader ]
%b.addr.07 = phi i8* [ %incdec.ptr1, %while.body ], [ %b, %while.body.preheader ]
%a.addr.06 = phi i8* [ %incdec.ptr, %while.body ], [ %a, %while.body.preheader ]
%dec = add nsw i32 %N.addr.09, -1
%incdec.ptr = getelementptr inbounds i8, i8* %a.addr.06, i32 1
%0 = load i8, i8* %a.addr.06, align 1
%incdec.ptr1 = getelementptr inbounds i8, i8* %b.addr.07, i32 1
%1 = load i8, i8* %b.addr.07, align 1
%add = add i8 %1, %0
%incdec.ptr4 = getelementptr inbounds i8, i8* %c.addr.08, i32 1
store i8 %add, i8* %c.addr.08, align 1
%cmp = icmp sgt i32 %N.addr.09, 1
br i1 %cmp, label %while.body, label %while.end.loopexit
while.end.loopexit:
br label %while.end
while.end:
ret void
}
define dso_local void @sgt_no_guard_0_startval(i8* noalias nocapture readonly %a, i8* noalias nocapture readonly %b, i8* noalias nocapture %c, i32 %N) local_unnamed_addr #0 {
; COMMON-LABEL: @sgt_no_guard_0_startval(
; COMMON-NOT: vector.body:
entry:
br label %while.body
while.body:
%N.addr.09 = phi i32 [ %dec, %while.body ], [ 0, %entry ]
%c.addr.08 = phi i8* [ %incdec.ptr4, %while.body ], [ %c, %entry ]
%b.addr.07 = phi i8* [ %incdec.ptr1, %while.body ], [ %b, %entry ]
%a.addr.06 = phi i8* [ %incdec.ptr, %while.body ], [ %a, %entry]
%dec = add nsw i32 %N.addr.09, -1
%incdec.ptr = getelementptr inbounds i8, i8* %a.addr.06, i32 1
%0 = load i8, i8* %a.addr.06, align 1
%incdec.ptr1 = getelementptr inbounds i8, i8* %b.addr.07, i32 1
%1 = load i8, i8* %b.addr.07, align 1
%add = add i8 %1, %0
%incdec.ptr4 = getelementptr inbounds i8, i8* %c.addr.08, i32 1
store i8 %add, i8* %c.addr.08, align 1
%cmp = icmp sgt i32 %N.addr.09, 1
br i1 %cmp, label %while.body, label %while.end.loopexit
while.end.loopexit:
br label %while.end
while.end:
ret void
}
define dso_local void @sgt_step_minus_two(i8* noalias nocapture readonly %a, i8* noalias nocapture readonly %b, i8* noalias nocapture %c, i32 %N) local_unnamed_addr #0 {
; COMMON-LABEL: @sgt_step_minus_two(
; COMMON: vector.body:
; CHECK-TF: masked.load
; CHECK-TF: masked.load
; CHECK-TF: masked.store
entry:
%cmp5 = icmp sgt i32 %N, 0
br i1 %cmp5, label %while.body.preheader, label %while.end
while.body.preheader:
br label %while.body
while.body:
%N.addr.09 = phi i32 [ %dec, %while.body ], [ %N, %while.body.preheader ]
%c.addr.08 = phi i8* [ %incdec.ptr4, %while.body ], [ %c, %while.body.preheader ]
%b.addr.07 = phi i8* [ %incdec.ptr1, %while.body ], [ %b, %while.body.preheader ]
%a.addr.06 = phi i8* [ %incdec.ptr, %while.body ], [ %a, %while.body.preheader ]
%dec = add nsw i32 %N.addr.09, -2
%incdec.ptr = getelementptr inbounds i8, i8* %a.addr.06, i32 1
%0 = load i8, i8* %a.addr.06, align 1
%incdec.ptr1 = getelementptr inbounds i8, i8* %b.addr.07, i32 1
%1 = load i8, i8* %b.addr.07, align 1
%add = add i8 %1, %0
%incdec.ptr4 = getelementptr inbounds i8, i8* %c.addr.08, i32 1
store i8 %add, i8* %c.addr.08, align 1
%cmp = icmp sgt i32 %N.addr.09, 1
br i1 %cmp, label %while.body, label %while.end.loopexit
while.end.loopexit:
br label %while.end
while.end:
ret void
}
define dso_local void @sgt_step_not_constant(i8* noalias nocapture readonly %a, i8* noalias nocapture readonly %b, i8* noalias nocapture %c, i32 %N, i32 %S) local_unnamed_addr #0 {
; COMMON-LABEL: @sgt_step_not_constant(
; COMMON-NOT: vector.body:
entry:
%cmp5 = icmp sgt i32 %N, 0
br i1 %cmp5, label %while.body.preheader, label %while.end
while.body.preheader:
br label %while.body
while.body:
%N.addr.09 = phi i32 [ %dec, %while.body ], [ %N, %while.body.preheader ]
%c.addr.08 = phi i8* [ %incdec.ptr4, %while.body ], [ %c, %while.body.preheader ]
%b.addr.07 = phi i8* [ %incdec.ptr1, %while.body ], [ %b, %while.body.preheader ]
%a.addr.06 = phi i8* [ %incdec.ptr, %while.body ], [ %a, %while.body.preheader ]
%dec = add nsw i32 %N.addr.09, %S
%incdec.ptr = getelementptr inbounds i8, i8* %a.addr.06, i32 1
%0 = load i8, i8* %a.addr.06, align 1
%incdec.ptr1 = getelementptr inbounds i8, i8* %b.addr.07, i32 1
%1 = load i8, i8* %b.addr.07, align 1
%add = add i8 %1, %0
%incdec.ptr4 = getelementptr inbounds i8, i8* %c.addr.08, i32 1
store i8 %add, i8* %c.addr.08, align 1
%cmp = icmp sgt i32 %N.addr.09, 1
br i1 %cmp, label %while.body, label %while.end.loopexit
while.end.loopexit:
br label %while.end
while.end:
ret void
}
define dso_local void @icmp_eq(i8* noalias nocapture readonly %A, i8* noalias nocapture readonly %B, i8* noalias nocapture %C, i32 %N) #0 {
; COMMON-LABEL: @icmp_eq
; COMMON: vector.body:
entry:
%cmp6 = icmp eq i32 %N, 0
br i1 %cmp6, label %while.end, label %while.body.preheader
while.body.preheader:
br label %while.body
while.body:
%N.addr.010 = phi i32 [ %dec, %while.body ], [ %N, %while.body.preheader ]
%C.addr.09 = phi i8* [ %incdec.ptr4, %while.body ], [ %C, %while.body.preheader ]
%B.addr.08 = phi i8* [ %incdec.ptr1, %while.body ], [ %B, %while.body.preheader ]
%A.addr.07 = phi i8* [ %incdec.ptr, %while.body ], [ %A, %while.body.preheader ]
%incdec.ptr = getelementptr inbounds i8, i8* %A.addr.07, i32 1
%0 = load i8, i8* %A.addr.07, align 1
%incdec.ptr1 = getelementptr inbounds i8, i8* %B.addr.08, i32 1
%1 = load i8, i8* %B.addr.08, align 1
%add = add i8 %1, %0
%incdec.ptr4 = getelementptr inbounds i8, i8* %C.addr.09, i32 1
store i8 %add, i8* %C.addr.09, align 1
%dec = add i32 %N.addr.010, -1
%cmp = icmp eq i32 %dec, 0
br i1 %cmp, label %while.end.loopexit, label %while.body
while.end.loopexit:
br label %while.end
while.end:
ret void
}
; This IR corresponds to this type of C-code:
;
; void f(char *a, char *b, char * __restrict c, int N) {
; #pragma clang loop vectorize_width(16)
; for (int i = N; i>0; i--)
; c[i] = a[i] + b[i];
; }
;
define dso_local void @sgt_for_loop(i8* noalias nocapture readonly %a, i8* noalias nocapture readonly %b, i8* noalias nocapture %c, i32 %N) local_unnamed_addr #0 {
; COMMON-LABEL: @sgt_for_loop(
; COMMON: vector.body:
; CHECK-PREFER: masked.load
; CHECK-PREFER: masked.load
; CHECK-PREFER: masked.store
;
; TODO: if tail-predication is requested, tail-folding isn't triggered because
; the profitability check returns "Different strides found, can't tail-predicate",
; investigate this.
;
; CHECK-ENABLE-TP-NOT: masked.load
; CHECK-ENABLE-TP-NOT: masked.load
; CHECK-ENABLE-TP-NOT: masked.store
;
entry:
%cmp5 = icmp sgt i32 %N, 0
br i1 %cmp5, label %for.body.preheader, label %for.end
for.body.preheader:
br label %for.body
for.body:
%i.011 = phi i32 [ %dec, %for.body ], [ %N, %for.body.preheader ]
%arrayidx = getelementptr inbounds i8, i8* %a, i32 %i.011
%0 = load i8, i8* %arrayidx, align 1
%arrayidx1 = getelementptr inbounds i8, i8* %b, i32 %i.011
%1 = load i8, i8* %arrayidx1, align 1
%add = add i8 %1, %0
%arrayidx4 = getelementptr inbounds i8, i8* %c, i32 %i.011
store i8 %add, i8* %arrayidx4, align 1
%dec = add nsw i32 %i.011, -1
%cmp = icmp sgt i32 %i.011, 1
br i1 %cmp, label %for.body, label %for.end, !llvm.loop !1
for.end:
ret void
}
define dso_local void @sgt_for_loop_i64(i8* noalias nocapture readonly %a, i8* noalias nocapture readonly %b, i8* noalias nocapture %c, i32 %N) local_unnamed_addr #0 {
; COMMON-LABEL: @sgt_for_loop_i64(
; COMMON: vector.body:
;
; CHECK-PREFER: masked.load
; CHECK-PREFER: masked.load
; CHECK-PREFER: masked.store
;
; With -disable-mve-tail-predication=false, the target hook returns
; "preferPredicateOverEpilogue: hardware-loop is not profitable."
; so here we don't expect the tail-folding. TODO: look into this.
;
; CHECK-ENABLE-TP-NOT: masked.load
; CHECK-ENABLE-TP-NOT: masked.load
; CHECK-ENABLE-TP-NOT: masked.store
;
entry:
%cmp14 = icmp sgt i32 %N, 0
br i1 %cmp14, label %for.body.preheader, label %for.cond.cleanup
for.body.preheader:
%conv16 = zext i32 %N to i64
br label %for.body
for.cond.cleanup.loopexit:
br label %for.cond.cleanup
for.cond.cleanup:
ret void
for.body:
%i.015 = phi i64 [ %dec, %for.body ], [ %conv16, %for.body.preheader ]
%idxprom = trunc i64 %i.015 to i32
%arrayidx = getelementptr inbounds i8, i8* %a, i32 %idxprom
%0 = load i8, i8* %arrayidx, align 1
%arrayidx4 = getelementptr inbounds i8, i8* %b, i32 %idxprom
%1 = load i8, i8* %arrayidx4, align 1
%add = add i8 %1, %0
%arrayidx8 = getelementptr inbounds i8, i8* %c, i32 %idxprom
store i8 %add, i8* %arrayidx8, align 1
%dec = add nsw i64 %i.015, -1
%cmp = icmp sgt i64 %i.015, 1
br i1 %cmp, label %for.body, label %for.cond.cleanup.loopexit, !llvm.loop !1
}
; This IR corresponds to this nested-loop:
;
; for (int i = 0; i<N; i++)
; for (int j = i+1; j>0; j--)
; c[j] = a[j] + b[j];
;
; while the inner-loop looks similar to previous examples, we can't
; transform this because the inner loop because isGuarded returns
; false for the inner-loop.
;
define dso_local void @sgt_nested_loop(i8* noalias nocapture readonly %a, i8* noalias nocapture readonly %b, i8* noalias nocapture %c, i32 %N) local_unnamed_addr #0 {
; COMMON-LABEL: @sgt_nested_loop(
; DEFAULT-NOT: vector.body:
; CHECK-TF-NOT: masked.load
; CHECK-TF-NOT: masked.load
; CHECK-TF-NOT: masked.store
; COMMON: }
;
entry:
%cmp21 = icmp sgt i32 %N, 0
br i1 %cmp21, label %for.body.preheader, label %for.cond.cleanup
for.body.preheader:
br label %for.body
for.cond.loopexit:
%exitcond = icmp eq i32 %add, %N
br i1 %exitcond, label %for.cond.cleanup.loopexit, label %for.body
for.cond.cleanup.loopexit:
br label %for.cond.cleanup
for.cond.cleanup:
ret void
for.body:
%i.022 = phi i32 [ %add, %for.cond.loopexit ], [ 0, %for.body.preheader ]
%add = add nuw nsw i32 %i.022, 1
br label %for.body4
for.body4: ; preds = %for.body, %for.body4
%j.020 = phi i32 [ %add, %for.body ], [ %dec, %for.body4 ]
%arrayidx = getelementptr inbounds i8, i8* %a, i32 %j.020
%0 = load i8, i8* %arrayidx, align 1
%arrayidx5 = getelementptr inbounds i8, i8* %b, i32 %j.020
%1 = load i8, i8* %arrayidx5, align 1
%add7 = add i8 %1, %0
%arrayidx9 = getelementptr inbounds i8, i8* %c, i32 %j.020
store i8 %add7, i8* %arrayidx9, align 1
%dec = add nsw i32 %j.020, -1
%cmp2 = icmp sgt i32 %j.020, 1
br i1 %cmp2, label %for.body4, label %for.cond.loopexit
}
attributes #0 = { nofree norecurse nounwind "target-features"="+armv8.1-m.main,+mve.fp" }
!1 = distinct !{!1, !2}
!2 = !{!"llvm.loop.vectorize.width", i32 16}