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[AArch64] Runtime-unroll small multi-exit loops on Apple Silicon. #124751

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Feb 27, 2025
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[AArch64] Runtime-unroll small multi-exit loops on Apple Silicon. #124751

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[AArch64] Runtime-unroll small multi-exit loops on Apple Silicon.
fhahn Jan 28, 2025
306a912
Merge branch 'main' into rt-multi-exit-apple-si
fhahn Feb 25, 2025
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35 changes: 28 additions & 7 deletions llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4129,15 +4129,14 @@ getAppleRuntimeUnrollPreferences(Loop *L, ScalarEvolution &SE,
TargetTransformInfo::UnrollingPreferences &UP,
AArch64TTIImpl &TTI) {
// Limit loops with structure that is highly likely to benefit from runtime
// unrolling; that is we exclude outer loops, loops with multiple exits and
// many blocks (i.e. likely with complex control flow). Note that the
// heuristics here may be overly conservative and we err on the side of
// avoiding runtime unrolling rather than unroll excessively. They are all
// subject to further refinement.
if (!L->isInnermost() || !L->getExitBlock() || L->getNumBlocks() > 8)
// unrolling; that is we exclude outer loops and loops with many blocks (i.e.
// likely with complex control flow). Note that the heuristics here may be
// overly conservative and we err on the side of avoiding runtime unrolling
// rather than unroll excessively. They are all subject to further refinement.
if (!L->isInnermost() || L->getNumBlocks() > 8)
return;

const SCEV *BTC = SE.getBackedgeTakenCount(L);
const SCEV *BTC = SE.getSymbolicMaxBackedgeTakenCount(L);
if (isa<SCEVConstant>(BTC) || isa<SCEVCouldNotCompute>(BTC) ||
(SE.getSmallConstantMaxTripCount(L) > 0 &&
SE.getSmallConstantMaxTripCount(L) <= 32))
Expand All @@ -4156,6 +4155,28 @@ getAppleRuntimeUnrollPreferences(Loop *L, ScalarEvolution &SE,
}
}

// Small search loops with multiple exits can be highly beneficial to unroll.
if (!L->getExitBlock()) {
if (L->getNumBlocks() == 2 && Size < 6 &&
all_of(
L->getBlocks(),
[](BasicBlock *BB) {
return isa<BranchInst>(BB->getTerminator());
})) {
UP.RuntimeUnrollMultiExit = true;
UP.Runtime = true;
// Limit unroll count.
UP.DefaultUnrollRuntimeCount = 4;
// Allow slightly more costly trip-count expansion to catch search loops
// with pointer inductions.
UP.SCEVExpansionBudget = 5;
}
return;
}

if (SE.getSymbolicMaxBackedgeTakenCount(L) != SE.getBackedgeTakenCount(L))
return;

// Limit to loops with trip counts that are cheap to expand.
UP.SCEVExpansionBudget = 1;

Expand Down
152 changes: 136 additions & 16 deletions llvm/test/Transforms/LoopUnroll/AArch64/apple-unrolling-multi-exit.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -13,22 +13,78 @@ define i1 @multi_2_exit_find_i8_loop(ptr %vec, i8 %tgt) {
; APPLE-SAME: ptr [[VEC:%.*]], i8 [[TGT:%.*]]) #[[ATTR0:[0-9]+]] {
; APPLE-NEXT: [[ENTRY:.*]]:
; APPLE-NEXT: [[START:%.*]] = load ptr, ptr [[VEC]], align 8
; APPLE-NEXT: [[START2:%.*]] = ptrtoint ptr [[START]] to i64
; APPLE-NEXT: [[GEP_END:%.*]] = getelementptr inbounds nuw i8, ptr [[VEC]], i64 1
; APPLE-NEXT: [[END:%.*]] = load ptr, ptr [[GEP_END]], align 8
; APPLE-NEXT: br label %[[LOOP_HEADER:.*]]
; APPLE: [[LOOP_HEADER]]:
; APPLE-NEXT: [[PTR_IV:%.*]] = phi ptr [ [[PTR_IV_NEXT:%.*]], %[[LOOP_LATCH:.*]] ], [ [[START]], %[[ENTRY]] ]
; APPLE-NEXT: [[END1:%.*]] = ptrtoint ptr [[END]] to i64
; APPLE-NEXT: [[TMP0:%.*]] = sub i64 [[END1]], [[START2]]
; APPLE-NEXT: [[TMP1:%.*]] = freeze i64 [[TMP0]]
; APPLE-NEXT: [[TMP2:%.*]] = add i64 [[TMP1]], -1
; APPLE-NEXT: [[XTRAITER:%.*]] = and i64 [[TMP1]], 3
; APPLE-NEXT: [[LCMP_MOD:%.*]] = icmp ne i64 [[XTRAITER]], 0
; APPLE-NEXT: br i1 [[LCMP_MOD]], label %[[LOOP_HEADER_PROL_PREHEADER:.*]], label %[[LOOP_HEADER_PROL_LOOPEXIT:.*]]
; APPLE: [[LOOP_HEADER_PROL_PREHEADER]]:
; APPLE-NEXT: br label %[[LOOP_HEADER_PROL:.*]]
; APPLE: [[LOOP_HEADER_PROL]]:
; APPLE-NEXT: [[PTR_IV:%.*]] = phi ptr [ [[PTR_IV_NEXT:%.*]], %[[LOOP_LATCH_PROL:.*]] ], [ [[START]], %[[LOOP_HEADER_PROL_PREHEADER]] ]
; APPLE-NEXT: [[PROL_ITER:%.*]] = phi i64 [ 0, %[[LOOP_HEADER_PROL_PREHEADER]] ], [ [[PROL_ITER_NEXT:%.*]], %[[LOOP_LATCH_PROL]] ]
; APPLE-NEXT: [[L:%.*]] = load i8, ptr [[PTR_IV]], align 8
; APPLE-NEXT: [[C_1:%.*]] = icmp eq i8 [[L]], [[TGT]]
; APPLE-NEXT: br i1 [[C_1]], label %[[EXIT:.*]], label %[[LOOP_LATCH]]
; APPLE: [[LOOP_LATCH]]:
; APPLE-NEXT: br i1 [[C_1]], label %[[EXIT_UNR_LCSSA_LOOPEXIT3:.*]], label %[[LOOP_LATCH_PROL]]
; APPLE: [[LOOP_LATCH_PROL]]:
; APPLE-NEXT: [[PTR_IV_NEXT]] = getelementptr inbounds nuw i8, ptr [[PTR_IV]], i64 1
; APPLE-NEXT: [[C_2:%.*]] = icmp eq ptr [[PTR_IV_NEXT]], [[END]]
; APPLE-NEXT: br i1 [[C_2]], label %[[EXIT]], label %[[LOOP_HEADER]]
; APPLE: [[EXIT]]:
; APPLE-NEXT: [[RES:%.*]] = phi ptr [ [[PTR_IV]], %[[LOOP_HEADER]] ], [ [[END]], %[[LOOP_LATCH]] ]
; APPLE-NEXT: [[PROL_ITER_NEXT]] = add i64 [[PROL_ITER]], 1
; APPLE-NEXT: [[PROL_ITER_CMP:%.*]] = icmp ne i64 [[PROL_ITER_NEXT]], [[XTRAITER]]
; APPLE-NEXT: br i1 [[PROL_ITER_CMP]], label %[[LOOP_HEADER_PROL]], label %[[LOOP_HEADER_PROL_LOOPEXIT_UNR_LCSSA:.*]], !llvm.loop [[LOOP0:![0-9]+]]
; APPLE: [[LOOP_HEADER_PROL_LOOPEXIT_UNR_LCSSA]]:
; APPLE-NEXT: [[RES_UNR_PH:%.*]] = phi ptr [ [[END]], %[[LOOP_LATCH_PROL]] ]
; APPLE-NEXT: [[PTR_IV_UNR_PH:%.*]] = phi ptr [ [[PTR_IV_NEXT]], %[[LOOP_LATCH_PROL]] ]
; APPLE-NEXT: br label %[[LOOP_HEADER_PROL_LOOPEXIT]]
; APPLE: [[LOOP_HEADER_PROL_LOOPEXIT]]:
; APPLE-NEXT: [[RES_UNR:%.*]] = phi ptr [ poison, %[[ENTRY]] ], [ [[RES_UNR_PH]], %[[LOOP_HEADER_PROL_LOOPEXIT_UNR_LCSSA]] ]
; APPLE-NEXT: [[PTR_IV_UNR:%.*]] = phi ptr [ [[START]], %[[ENTRY]] ], [ [[PTR_IV_UNR_PH]], %[[LOOP_HEADER_PROL_LOOPEXIT_UNR_LCSSA]] ]
; APPLE-NEXT: [[TMP3:%.*]] = icmp ult i64 [[TMP2]], 3
; APPLE-NEXT: br i1 [[TMP3]], label %[[EXIT:.*]], label %[[ENTRY_NEW:.*]]
; APPLE: [[ENTRY_NEW]]:
; APPLE-NEXT: br label %[[LOOP_HEADER:.*]]
; APPLE: [[LOOP_HEADER]]:
; APPLE-NEXT: [[PTR_IV1:%.*]] = phi ptr [ [[PTR_IV_UNR]], %[[ENTRY_NEW]] ], [ [[RES:%.*]], %[[LOOP_LATCH_3:.*]] ]
; APPLE-NEXT: [[L1:%.*]] = load i8, ptr [[PTR_IV1]], align 8
; APPLE-NEXT: [[C_4:%.*]] = icmp eq i8 [[L1]], [[TGT]]
; APPLE-NEXT: br i1 [[C_4]], label %[[EXIT_UNR_LCSSA_LOOPEXIT:.*]], label %[[LOOP_LATCH:.*]]
; APPLE: [[LOOP_LATCH]]:
; APPLE-NEXT: [[PTR_IV_NEXT1:%.*]] = getelementptr inbounds nuw i8, ptr [[PTR_IV1]], i64 1
; APPLE-NEXT: [[L_1:%.*]] = load i8, ptr [[PTR_IV_NEXT1]], align 8
; APPLE-NEXT: [[C_1_1:%.*]] = icmp eq i8 [[L_1]], [[TGT]]
; APPLE-NEXT: br i1 [[C_1_1]], label %[[EXIT_UNR_LCSSA_LOOPEXIT]], label %[[LOOP_LATCH_1:.*]]
; APPLE: [[LOOP_LATCH_1]]:
; APPLE-NEXT: [[PTR_IV_NEXT_1:%.*]] = getelementptr inbounds nuw i8, ptr [[PTR_IV_NEXT1]], i64 1
; APPLE-NEXT: [[L_2:%.*]] = load i8, ptr [[PTR_IV_NEXT_1]], align 8
; APPLE-NEXT: [[C_1_2:%.*]] = icmp eq i8 [[L_2]], [[TGT]]
; APPLE-NEXT: br i1 [[C_1_2]], label %[[EXIT_UNR_LCSSA_LOOPEXIT]], label %[[LOOP_LATCH_2:.*]]
; APPLE: [[LOOP_LATCH_2]]:
; APPLE-NEXT: [[PTR_IV_NEXT_2:%.*]] = getelementptr inbounds nuw i8, ptr [[PTR_IV_NEXT_1]], i64 1
; APPLE-NEXT: [[L_3:%.*]] = load i8, ptr [[PTR_IV_NEXT_2]], align 8
; APPLE-NEXT: [[C_1_3:%.*]] = icmp eq i8 [[L_3]], [[TGT]]
; APPLE-NEXT: br i1 [[C_1_3]], label %[[EXIT_UNR_LCSSA_LOOPEXIT]], label %[[LOOP_LATCH_3]]
; APPLE: [[LOOP_LATCH_3]]:
; APPLE-NEXT: [[RES]] = getelementptr inbounds nuw i8, ptr [[PTR_IV_NEXT_2]], i64 1
; APPLE-NEXT: [[C_3:%.*]] = icmp eq ptr [[RES]], [[END]]
; APPLE-NEXT: ret i1 [[C_3]]
; APPLE-NEXT: br i1 [[C_3]], label %[[EXIT_UNR_LCSSA_LOOPEXIT]], label %[[LOOP_HEADER]]
; APPLE: [[EXIT_UNR_LCSSA_LOOPEXIT]]:
; APPLE-NEXT: [[RES_PH_PH:%.*]] = phi ptr [ [[PTR_IV1]], %[[LOOP_HEADER]] ], [ [[PTR_IV_NEXT1]], %[[LOOP_LATCH]] ], [ [[PTR_IV_NEXT_1]], %[[LOOP_LATCH_1]] ], [ [[PTR_IV_NEXT_2]], %[[LOOP_LATCH_2]] ], [ [[END]], %[[LOOP_LATCH_3]] ]
; APPLE-NEXT: br label %[[EXIT_UNR_LCSSA:.*]]
; APPLE: [[EXIT_UNR_LCSSA_LOOPEXIT3]]:
; APPLE-NEXT: [[RES_PH_PH4:%.*]] = phi ptr [ [[PTR_IV]], %[[LOOP_HEADER_PROL]] ]
; APPLE-NEXT: br label %[[EXIT_UNR_LCSSA]]
; APPLE: [[EXIT_UNR_LCSSA]]:
; APPLE-NEXT: [[RES_PH:%.*]] = phi ptr [ [[RES_PH_PH]], %[[EXIT_UNR_LCSSA_LOOPEXIT]] ], [ [[RES_PH_PH4]], %[[EXIT_UNR_LCSSA_LOOPEXIT3]] ]
; APPLE-NEXT: br label %[[EXIT]]
; APPLE: [[EXIT]]:
; APPLE-NEXT: [[RES1:%.*]] = phi ptr [ [[RES_UNR]], %[[LOOP_HEADER_PROL_LOOPEXIT]] ], [ [[RES_PH]], %[[EXIT_UNR_LCSSA]] ]
; APPLE-NEXT: [[C_5:%.*]] = icmp eq ptr [[RES1]], [[END]]
; APPLE-NEXT: ret i1 [[C_5]]
;
; OTHER-LABEL: define i1 @multi_2_exit_find_i8_loop(
; OTHER-SAME: ptr [[VEC:%.*]], i8 [[TGT:%.*]]) #[[ATTR0:[0-9]+]] {
Expand Down Expand Up @@ -80,22 +136,81 @@ define i1 @multi_2_exit_find_ptr_loop(ptr %vec, ptr %tgt) {
; APPLE-SAME: ptr [[VEC:%.*]], ptr [[TGT:%.*]]) #[[ATTR0]] {
; APPLE-NEXT: [[ENTRY:.*]]:
; APPLE-NEXT: [[START:%.*]] = load ptr, ptr [[VEC]], align 8
; APPLE-NEXT: [[START2:%.*]] = ptrtoint ptr [[START]] to i64
; APPLE-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[START]], i64 8) ]
; APPLE-NEXT: [[GEP_END:%.*]] = getelementptr inbounds nuw i8, ptr [[VEC]], i64 8
; APPLE-NEXT: [[END:%.*]] = load ptr, ptr [[GEP_END]], align 8
; APPLE-NEXT: [[END1:%.*]] = ptrtoint ptr [[END]] to i64
; APPLE-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[END]], i64 8) ]
; APPLE-NEXT: br label %[[LOOP_HEADER:.*]]
; APPLE: [[LOOP_HEADER]]:
; APPLE-NEXT: [[PTR_IV:%.*]] = phi ptr [ [[PTR_IV_NEXT:%.*]], %[[LOOP_LATCH:.*]] ], [ [[START]], %[[ENTRY]] ]
; APPLE-NEXT: [[TMP0:%.*]] = add i64 [[END1]], -8
; APPLE-NEXT: [[TMP1:%.*]] = sub i64 [[TMP0]], [[START2]]
; APPLE-NEXT: [[TMP2:%.*]] = lshr i64 [[TMP1]], 3
; APPLE-NEXT: [[TMP3:%.*]] = add nuw nsw i64 [[TMP2]], 1
; APPLE-NEXT: [[TMP4:%.*]] = freeze i64 [[TMP3]]
; APPLE-NEXT: [[TMP5:%.*]] = add i64 [[TMP4]], -1
; APPLE-NEXT: [[XTRAITER:%.*]] = and i64 [[TMP4]], 3
; APPLE-NEXT: [[LCMP_MOD:%.*]] = icmp ne i64 [[XTRAITER]], 0
; APPLE-NEXT: br i1 [[LCMP_MOD]], label %[[LOOP_HEADER_PROL_PREHEADER:.*]], label %[[LOOP_HEADER_PROL_LOOPEXIT:.*]]
; APPLE: [[LOOP_HEADER_PROL_PREHEADER]]:
; APPLE-NEXT: br label %[[LOOP_HEADER_PROL:.*]]
; APPLE: [[LOOP_HEADER_PROL]]:
; APPLE-NEXT: [[PTR_IV:%.*]] = phi ptr [ [[PTR_IV_NEXT:%.*]], %[[LOOP_LATCH_PROL:.*]] ], [ [[START]], %[[LOOP_HEADER_PROL_PREHEADER]] ]
; APPLE-NEXT: [[PROL_ITER:%.*]] = phi i64 [ 0, %[[LOOP_HEADER_PROL_PREHEADER]] ], [ [[PROL_ITER_NEXT:%.*]], %[[LOOP_LATCH_PROL]] ]
; APPLE-NEXT: [[L:%.*]] = load ptr, ptr [[PTR_IV]], align 8
; APPLE-NEXT: [[C_1:%.*]] = icmp eq ptr [[L]], [[TGT]]
; APPLE-NEXT: br i1 [[C_1]], label %[[EXIT:.*]], label %[[LOOP_LATCH]]
; APPLE: [[LOOP_LATCH]]:
; APPLE-NEXT: br i1 [[C_1]], label %[[EXIT_UNR_LCSSA_LOOPEXIT3:.*]], label %[[LOOP_LATCH_PROL]]
; APPLE: [[LOOP_LATCH_PROL]]:
; APPLE-NEXT: [[PTR_IV_NEXT]] = getelementptr inbounds nuw i8, ptr [[PTR_IV]], i64 8
; APPLE-NEXT: [[C_2:%.*]] = icmp eq ptr [[PTR_IV_NEXT]], [[END]]
; APPLE-NEXT: br i1 [[C_2]], label %[[EXIT]], label %[[LOOP_HEADER]]
; APPLE-NEXT: [[PROL_ITER_NEXT]] = add i64 [[PROL_ITER]], 1
; APPLE-NEXT: [[PROL_ITER_CMP:%.*]] = icmp ne i64 [[PROL_ITER_NEXT]], [[XTRAITER]]
; APPLE-NEXT: br i1 [[PROL_ITER_CMP]], label %[[LOOP_HEADER_PROL]], label %[[LOOP_HEADER_PROL_LOOPEXIT_UNR_LCSSA:.*]], !llvm.loop [[LOOP2:![0-9]+]]
; APPLE: [[LOOP_HEADER_PROL_LOOPEXIT_UNR_LCSSA]]:
; APPLE-NEXT: [[RES_UNR_PH:%.*]] = phi ptr [ [[END]], %[[LOOP_LATCH_PROL]] ]
; APPLE-NEXT: [[PTR_IV_UNR_PH:%.*]] = phi ptr [ [[PTR_IV_NEXT]], %[[LOOP_LATCH_PROL]] ]
; APPLE-NEXT: br label %[[LOOP_HEADER_PROL_LOOPEXIT]]
; APPLE: [[LOOP_HEADER_PROL_LOOPEXIT]]:
; APPLE-NEXT: [[RES_UNR:%.*]] = phi ptr [ poison, %[[ENTRY]] ], [ [[RES_UNR_PH]], %[[LOOP_HEADER_PROL_LOOPEXIT_UNR_LCSSA]] ]
; APPLE-NEXT: [[PTR_IV_UNR:%.*]] = phi ptr [ [[START]], %[[ENTRY]] ], [ [[PTR_IV_UNR_PH]], %[[LOOP_HEADER_PROL_LOOPEXIT_UNR_LCSSA]] ]
; APPLE-NEXT: [[TMP6:%.*]] = icmp ult i64 [[TMP5]], 3
; APPLE-NEXT: br i1 [[TMP6]], label %[[EXIT:.*]], label %[[ENTRY_NEW:.*]]
; APPLE: [[ENTRY_NEW]]:
; APPLE-NEXT: br label %[[LOOP_HEADER:.*]]
; APPLE: [[LOOP_HEADER]]:
; APPLE-NEXT: [[PTR_IV1:%.*]] = phi ptr [ [[PTR_IV_UNR]], %[[ENTRY_NEW]] ], [ [[PTR_IV_NEXT_3:%.*]], %[[LOOP_LATCH_3:.*]] ]
; APPLE-NEXT: [[L1:%.*]] = load ptr, ptr [[PTR_IV1]], align 8
; APPLE-NEXT: [[C_4:%.*]] = icmp eq ptr [[L1]], [[TGT]]
; APPLE-NEXT: br i1 [[C_4]], label %[[EXIT_UNR_LCSSA_LOOPEXIT:.*]], label %[[LOOP_LATCH:.*]]
; APPLE: [[LOOP_LATCH]]:
; APPLE-NEXT: [[PTR_IV_NEXT1:%.*]] = getelementptr inbounds nuw i8, ptr [[PTR_IV1]], i64 8
; APPLE-NEXT: [[L_1:%.*]] = load ptr, ptr [[PTR_IV_NEXT1]], align 8
; APPLE-NEXT: [[C_1_1:%.*]] = icmp eq ptr [[L_1]], [[TGT]]
; APPLE-NEXT: br i1 [[C_1_1]], label %[[EXIT_UNR_LCSSA_LOOPEXIT]], label %[[LOOP_LATCH_1:.*]]
; APPLE: [[LOOP_LATCH_1]]:
; APPLE-NEXT: [[PTR_IV_NEXT_1:%.*]] = getelementptr inbounds nuw i8, ptr [[PTR_IV_NEXT1]], i64 8
; APPLE-NEXT: [[L_2:%.*]] = load ptr, ptr [[PTR_IV_NEXT_1]], align 8
; APPLE-NEXT: [[C_1_2:%.*]] = icmp eq ptr [[L_2]], [[TGT]]
; APPLE-NEXT: br i1 [[C_1_2]], label %[[EXIT_UNR_LCSSA_LOOPEXIT]], label %[[LOOP_LATCH_2:.*]]
; APPLE: [[LOOP_LATCH_2]]:
; APPLE-NEXT: [[PTR_IV_NEXT_2:%.*]] = getelementptr inbounds nuw i8, ptr [[PTR_IV_NEXT_1]], i64 8
; APPLE-NEXT: [[L_3:%.*]] = load ptr, ptr [[PTR_IV_NEXT_2]], align 8
; APPLE-NEXT: [[C_1_3:%.*]] = icmp eq ptr [[L_3]], [[TGT]]
; APPLE-NEXT: br i1 [[C_1_3]], label %[[EXIT_UNR_LCSSA_LOOPEXIT]], label %[[LOOP_LATCH_3]]
; APPLE: [[LOOP_LATCH_3]]:
; APPLE-NEXT: [[PTR_IV_NEXT_3]] = getelementptr inbounds nuw i8, ptr [[PTR_IV_NEXT_2]], i64 8
; APPLE-NEXT: [[C_2_3:%.*]] = icmp eq ptr [[PTR_IV_NEXT_3]], [[END]]
; APPLE-NEXT: br i1 [[C_2_3]], label %[[EXIT_UNR_LCSSA_LOOPEXIT]], label %[[LOOP_HEADER]]
; APPLE: [[EXIT_UNR_LCSSA_LOOPEXIT]]:
; APPLE-NEXT: [[RES_PH_PH:%.*]] = phi ptr [ [[PTR_IV1]], %[[LOOP_HEADER]] ], [ [[PTR_IV_NEXT1]], %[[LOOP_LATCH]] ], [ [[PTR_IV_NEXT_1]], %[[LOOP_LATCH_1]] ], [ [[PTR_IV_NEXT_2]], %[[LOOP_LATCH_2]] ], [ [[END]], %[[LOOP_LATCH_3]] ]
; APPLE-NEXT: br label %[[EXIT_UNR_LCSSA:.*]]
; APPLE: [[EXIT_UNR_LCSSA_LOOPEXIT3]]:
; APPLE-NEXT: [[RES_PH_PH4:%.*]] = phi ptr [ [[PTR_IV]], %[[LOOP_HEADER_PROL]] ]
; APPLE-NEXT: br label %[[EXIT_UNR_LCSSA]]
; APPLE: [[EXIT_UNR_LCSSA]]:
; APPLE-NEXT: [[RES_PH:%.*]] = phi ptr [ [[RES_PH_PH]], %[[EXIT_UNR_LCSSA_LOOPEXIT]] ], [ [[RES_PH_PH4]], %[[EXIT_UNR_LCSSA_LOOPEXIT3]] ]
; APPLE-NEXT: br label %[[EXIT]]
; APPLE: [[EXIT]]:
; APPLE-NEXT: [[RES:%.*]] = phi ptr [ [[PTR_IV]], %[[LOOP_HEADER]] ], [ [[END]], %[[LOOP_LATCH]] ]
; APPLE-NEXT: [[RES:%.*]] = phi ptr [ [[RES_UNR]], %[[LOOP_HEADER_PROL_LOOPEXIT]] ], [ [[RES_PH]], %[[EXIT_UNR_LCSSA]] ]
; APPLE-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[END]], i64 8) ]
; APPLE-NEXT: [[C_3:%.*]] = icmp eq ptr [[RES]], [[END]]
; APPLE-NEXT: ret i1 [[C_3]]
Expand Down Expand Up @@ -393,3 +508,8 @@ exit.2:
}

declare void @llvm.assume(i1 noundef)
;.
; APPLE: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]]}
; APPLE: [[META1]] = !{!"llvm.loop.unroll.disable"}
; APPLE: [[LOOP2]] = distinct !{[[LOOP2]], [[META1]]}
;.