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llvm-project/llvm/test/Transforms/LoopVectorize/make-followup-loop-id.ll
Florian Hahn 50b9ca4dda
[VPlan] Simplify Plan's entry in removeBranchOnConst. (#154510) 
After https://github.com/llvm/llvm-project/pull/153643, there may be a
BranchOnCond with constant condition in the entry block.

Simplify those in removeBranchOnConst. This removes a number of
redundant conditional branch from entry blocks.

In some cases, it may also make the original scalar loop unreachable,
because we know it will never execute. In that case, we need to remove
the loop from LoopInfo, because all unreachable blocks may dominate each
other, making LoopInfo invalid. In those cases, we can also completely
remove the loop, for which I'll share a follow-up patch.

Depends on https://github.com/llvm/llvm-project/pull/153643.

PR: https://github.com/llvm/llvm-project/pull/154510
2025-09-18 19:25:05 +01:00

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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -passes='loop-vectorize' -force-vector-width=4 -S < %s | FileCheck %s
; Test if the follow-up metadata for loops works fine. The original code is
; something like below. In this case, the unrolling metadata from the original
; loop should be applied to the vector loop as well.
;
; void f(float *a, float x) {
; #pragma clang loop vectorize(enable) unroll_count(8)
; for (int i = 0; i < 1024; i++) {
; a[i] *= x;
; }
; }
;
define void @scalar_loop_dead(ptr noundef captures(none) %a, float noundef %x) {
; CHECK-LABEL: define void @scalar_loop_dead(
; CHECK-SAME: ptr noundef captures(none) [[A:%.*]], float noundef [[X:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: br label %[[VECTOR_PH:.*]]
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x float> poison, float [[X]], i64 0
; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x float> [[BROADCAST_SPLATINSERT]], <4 x float> poison, <4 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: [[TMP0:%.*]] = getelementptr inbounds nuw float, ptr [[A]], i64 [[INDEX]]
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <4 x float>, ptr [[TMP0]], align 4
; CHECK-NEXT: [[TMP1:%.*]] = fmul <4 x float> [[BROADCAST_SPLAT]], [[WIDE_LOAD]]
; CHECK-NEXT: store <4 x float> [[TMP1]], ptr [[TMP0]], align 4
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
; CHECK-NEXT: [[TMP2:%.*]] = icmp eq i64 [[INDEX_NEXT]], 1024
; CHECK-NEXT: br i1 [[TMP2]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
; CHECK: [[MIDDLE_BLOCK]]:
; CHECK-NEXT: br label %[[EXIT:.*]]
; CHECK: [[SCALAR_PH:.*]]:
; CHECK-NEXT: br label %[[LOOP:.*]]
; CHECK: [[LOOP]]:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 0, %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds nuw float, ptr [[A]], i64 [[IV]]
; CHECK-NEXT: [[LOAD:%.*]] = load float, ptr [[ARRAYIDX]], align 4
; CHECK-NEXT: [[MUL:%.*]] = fmul float [[X]], [[LOAD]]
; CHECK-NEXT: store float [[MUL]], ptr [[ARRAYIDX]], align 4
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[COMP:%.*]] = icmp eq i64 [[IV_NEXT]], 1024
; CHECK-NEXT: br i1 [[COMP]], label %[[EXIT]], label %[[LOOP]], !llvm.loop [[LOOP4:![0-9]+]]
; CHECK: [[EXIT]]:
; CHECK-NEXT: ret void
;
entry:
br label %loop
loop:
%iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
%arrayidx = getelementptr inbounds nuw float, ptr %a, i64 %iv
%load = load float, ptr %arrayidx, align 4
%mul = fmul float %x, %load
store float %mul, ptr %arrayidx, align 4
%iv.next = add nuw nsw i64 %iv, 1
%comp = icmp eq i64 %iv.next, 1024
br i1 %comp, label %exit, label %loop, !llvm.loop !0
exit:
ret void
}
define void @scalar_loop_live(ptr noundef captures(none) %a, float noundef %x, i64 %n) {
; CHECK-LABEL: define void @scalar_loop_live(
; CHECK-SAME: ptr noundef captures(none) [[A:%.*]], float noundef [[X:%.*]], i64 [[N:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*]]:
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[N]], 4
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 [[N]], 4
; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x float> poison, float [[X]], i64 0
; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x float> [[BROADCAST_SPLATINSERT]], <4 x float> poison, <4 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: [[TMP0:%.*]] = getelementptr inbounds nuw float, ptr [[A]], i64 [[INDEX]]
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <4 x float>, ptr [[TMP0]], align 4
; CHECK-NEXT: [[TMP1:%.*]] = fmul <4 x float> [[BROADCAST_SPLAT]], [[WIDE_LOAD]]
; CHECK-NEXT: store <4 x float> [[TMP1]], ptr [[TMP0]], align 4
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
; CHECK-NEXT: [[TMP2:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP2]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP7:![0-9]+]]
; CHECK: [[MIDDLE_BLOCK]]:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[N]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label %[[EXIT:.*]], label %[[SCALAR_PH]]
; CHECK: [[SCALAR_PH]]:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
; CHECK-NEXT: br label %[[LOOP:.*]]
; CHECK: [[LOOP]]:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds nuw float, ptr [[A]], i64 [[IV]]
; CHECK-NEXT: [[LOAD:%.*]] = load float, ptr [[ARRAYIDX]], align 4
; CHECK-NEXT: [[MUL:%.*]] = fmul float [[X]], [[LOAD]]
; CHECK-NEXT: store float [[MUL]], ptr [[ARRAYIDX]], align 4
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[COMP:%.*]] = icmp eq i64 [[IV_NEXT]], [[N]]
; CHECK-NEXT: br i1 [[COMP]], label %[[EXIT]], label %[[LOOP]], !llvm.loop [[LOOP8:![0-9]+]]
; CHECK: [[EXIT]]:
; CHECK-NEXT: ret void
;
entry:
br label %loop
loop:
%iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
%arrayidx = getelementptr inbounds nuw float, ptr %a, i64 %iv
%load = load float, ptr %arrayidx, align 4
%mul = fmul float %x, %load
store float %mul, ptr %arrayidx, align 4
%iv.next = add nuw nsw i64 %iv, 1
%comp = icmp eq i64 %iv.next, %n
br i1 %comp, label %exit, label %loop, !llvm.loop !0
exit:
ret void
}
!0 = distinct !{!0, !1, !2}
!1 = !{!"llvm.loop.vectorize.enable", i1 true}
!2 = !{!"llvm.loop.vectorize.followup_all", !3, !4}
!3 = !{!"llvm.loop.isvectorized"}
!4 = !{!"llvm.loop.unroll.count", i32 8}
;.
; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]], [[META2:![0-9]+]], [[META3:![0-9]+]]}
; CHECK: [[META1]] = !{!"llvm.loop.isvectorized"}
; CHECK: [[META2]] = !{!"llvm.loop.unroll.count", i32 8}
; CHECK: [[META3]] = !{!"llvm.loop.unroll.runtime.disable"}
; CHECK: [[LOOP4]] = distinct !{[[LOOP4]], [[META5:![0-9]+]], [[META6:![0-9]+]]}
; CHECK: [[META5]] = !{!"llvm.loop.vectorize.enable", i1 true}
; CHECK: [[META6]] = !{!"llvm.loop.vectorize.followup_all", [[META1]], [[META2]]}
; CHECK: [[LOOP7]] = distinct !{[[LOOP7]], [[META1]], [[META2]], [[META3]]}
; CHECK: [[LOOP8]] = distinct !{[[LOOP8]], [[META1]], [[META2]]}
;.
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