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clang-p2996/llvm/test/Transforms/LoopUnroll/nonlatchcondbr.ll
Nikita Popov b9808e5660 [LoopUnroll] Fold add chains during unrolling 
Loop unrolling tends to produce chains of
`%x1 = add %x0, 1; %x2 = add %x1, 1; ...` with one add per unrolled
iteration. This patch simplifies these adds to `%xN = add %x0, N`
directly during unrolling, rather than waiting for InstCombine to do so.

The motivation for this is that having a single add (rather than
an add chain) on the induction variable makes it a simple recurrence,
which we specially recognize in a number of places. This allows
InstCombine to directly perform folds with that knowledge, instead
of first folding the add chains, and then doing other folds in another
InstCombine iteration.

Due to the reduced number of InstCombine iterations, this also
results in a small compile-time improvement.

Differential Revision: https://reviews.llvm.org/D153540
2023-07-05 09:54:28 +02:00

256 lines
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -passes=loop-unroll -unroll-runtime -unroll-count=4 -S | FileCheck %s
; RUN: opt < %s -passes='require<opt-remark-emit>,loop-unroll' -unroll-runtime -unroll-count=4 -S | FileCheck %s
; Check that loop unroll pass correctly handle loops with
; single exiting block not the loop header or latch.
define void @test1(ptr noalias %A) {
; CHECK-LABEL: @test1(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[A:%.*]], align 4
; CHECK-NEXT: call void @bar(i32 [[TMP0]])
; CHECK-NEXT: br label [[FOR_HEADER:%.*]]
; CHECK: for.header:
; CHECK-NEXT: call void @bar(i32 [[TMP0]])
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: br label [[FOR_BODY_FOR_BODY_CRIT_EDGE:%.*]]
; CHECK: for.body.for.body_crit_edge:
; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 1
; CHECK-NEXT: [[DOTPRE:%.*]] = load i32, ptr [[ARRAYIDX_PHI_TRANS_INSERT]], align 4
; CHECK-NEXT: call void @bar(i32 [[DOTPRE]])
; CHECK-NEXT: br label [[FOR_BODY_1:%.*]]
; CHECK: for.body.1:
; CHECK-NEXT: br label [[FOR_BODY_FOR_BODY_CRIT_EDGE_1:%.*]]
; CHECK: for.body.for.body_crit_edge.1:
; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT_1:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 2
; CHECK-NEXT: [[DOTPRE_1:%.*]] = load i32, ptr [[ARRAYIDX_PHI_TRANS_INSERT_1]], align 4
; CHECK-NEXT: call void @bar(i32 [[DOTPRE_1]])
; CHECK-NEXT: br label [[FOR_BODY_2:%.*]]
; CHECK: for.body.2:
; CHECK-NEXT: br label [[FOR_BODY_FOR_BODY_CRIT_EDGE_2:%.*]]
; CHECK: for.body.for.body_crit_edge.2:
; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT_2:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 3
; CHECK-NEXT: [[DOTPRE_2:%.*]] = load i32, ptr [[ARRAYIDX_PHI_TRANS_INSERT_2]], align 4
; CHECK-NEXT: call void @bar(i32 [[DOTPRE_2]])
; CHECK-NEXT: br label [[FOR_BODY_3:%.*]]
; CHECK: for.body.3:
; CHECK-NEXT: br i1 false, label [[FOR_BODY_FOR_BODY_CRIT_EDGE_3:%.*]], label [[FOR_END:%.*]]
; CHECK: for.body.for.body_crit_edge.3:
; CHECK-NEXT: unreachable
; CHECK: for.end:
; CHECK-NEXT: ret void
;
entry:
%0 = load i32, ptr %A, align 4
call void @bar(i32 %0)
br label %for.header
for.header:
%1 = phi i32 [ %0, %entry ], [ %.pre, %for.body.for.body_crit_edge ]
%i = phi i64 [ 0, %entry ], [ %inc, %for.body.for.body_crit_edge ]
%arrayidx = getelementptr inbounds i32, ptr %A, i64 %i
call void @bar(i32 %1)
br label %for.body
for.body:
%inc = add nsw i64 %i, 1
%cmp = icmp slt i64 %inc, 4
br i1 %cmp, label %for.body.for.body_crit_edge, label %for.end
for.body.for.body_crit_edge:
%arrayidx.phi.trans.insert = getelementptr inbounds i32, ptr %A, i64 %inc
%.pre = load i32, ptr %arrayidx.phi.trans.insert, align 4
br label %for.header
for.end:
ret void
}
; Check that loop unroll pass correctly handle loops with
; (1) exiting block not dominating the loop latch; and
; (2) exiting terminator instructions cannot be simplified to unconditional.
define void @test2(ptr noalias %A) {
; CHECK-LABEL: @test2(
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 true, label [[FOR_PREHEADER:%.*]], label [[FOR_END:%.*]]
; CHECK: for.preheader:
; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[A:%.*]], align 4
; CHECK-NEXT: call void @bar(i32 [[TMP0]])
; CHECK-NEXT: br label [[FOR_HEADER:%.*]]
; CHECK: for.header:
; CHECK-NEXT: [[TMP1:%.*]] = phi i32 [ [[TMP0]], [[FOR_PREHEADER]] ], [ [[DOTPRE_3:%.*]], [[FOR_BODY_FOR_BODY_CRIT_EDGE_3:%.*]] ]
; CHECK-NEXT: [[I:%.*]] = phi i64 [ 0, [[FOR_PREHEADER]] ], [ [[INC_3:%.*]], [[FOR_BODY_FOR_BODY_CRIT_EDGE_3]] ]
; CHECK-NEXT: call void @bar(i32 [[TMP1]])
; CHECK-NEXT: [[INC:%.*]] = add nuw nsw i64 [[I]], 1
; CHECK-NEXT: br i1 true, label [[FOR_BODY:%.*]], label [[FOR_BODY_FOR_BODY_CRIT_EDGE:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[CMP:%.*]] = call i1 @foo(i64 [[I]])
; CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY_FOR_BODY_CRIT_EDGE]], label [[FOR_END_LOOPEXIT:%.*]]
; CHECK: for.body.for.body_crit_edge:
; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 [[INC]]
; CHECK-NEXT: [[DOTPRE:%.*]] = load i32, ptr [[ARRAYIDX_PHI_TRANS_INSERT]], align 4
; CHECK-NEXT: call void @bar(i32 [[DOTPRE]])
; CHECK-NEXT: [[INC_1:%.*]] = add nuw nsw i64 [[I]], 2
; CHECK-NEXT: br i1 true, label [[FOR_BODY_1:%.*]], label [[FOR_BODY_FOR_BODY_CRIT_EDGE_1:%.*]]
; CHECK: for.body.1:
; CHECK-NEXT: [[CMP_1:%.*]] = call i1 @foo(i64 [[INC]])
; CHECK-NEXT: br i1 [[CMP_1]], label [[FOR_BODY_FOR_BODY_CRIT_EDGE_1]], label [[FOR_END_LOOPEXIT]]
; CHECK: for.body.for.body_crit_edge.1:
; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT_1:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 [[INC_1]]
; CHECK-NEXT: [[DOTPRE_1:%.*]] = load i32, ptr [[ARRAYIDX_PHI_TRANS_INSERT_1]], align 4
; CHECK-NEXT: call void @bar(i32 [[DOTPRE_1]])
; CHECK-NEXT: [[INC_2:%.*]] = add nuw nsw i64 [[I]], 3
; CHECK-NEXT: br i1 true, label [[FOR_BODY_2:%.*]], label [[FOR_BODY_FOR_BODY_CRIT_EDGE_2:%.*]]
; CHECK: for.body.2:
; CHECK-NEXT: [[CMP_2:%.*]] = call i1 @foo(i64 [[INC_1]])
; CHECK-NEXT: br i1 [[CMP_2]], label [[FOR_BODY_FOR_BODY_CRIT_EDGE_2]], label [[FOR_END_LOOPEXIT]]
; CHECK: for.body.for.body_crit_edge.2:
; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT_2:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 [[INC_2]]
; CHECK-NEXT: [[DOTPRE_2:%.*]] = load i32, ptr [[ARRAYIDX_PHI_TRANS_INSERT_2]], align 4
; CHECK-NEXT: call void @bar(i32 [[DOTPRE_2]])
; CHECK-NEXT: [[INC_3]] = add nsw i64 [[I]], 4
; CHECK-NEXT: br i1 true, label [[FOR_BODY_3:%.*]], label [[FOR_BODY_FOR_BODY_CRIT_EDGE_3]]
; CHECK: for.body.3:
; CHECK-NEXT: [[CMP_3:%.*]] = call i1 @foo(i64 [[INC_2]])
; CHECK-NEXT: br i1 [[CMP_3]], label [[FOR_BODY_FOR_BODY_CRIT_EDGE_3]], label [[FOR_END_LOOPEXIT]]
; CHECK: for.body.for.body_crit_edge.3:
; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT_3:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 [[INC_3]]
; CHECK-NEXT: [[DOTPRE_3]] = load i32, ptr [[ARRAYIDX_PHI_TRANS_INSERT_3]], align 4
; CHECK-NEXT: br label [[FOR_HEADER]], !llvm.loop [[LOOP0:![0-9]+]]
; CHECK: for.end.loopexit:
; CHECK-NEXT: br label [[FOR_END]]
; CHECK: for.end:
; CHECK-NEXT: ret void
;
entry:
br i1 true, label %for.preheader, label %for.end
for.preheader:
%0 = load i32, ptr %A, align 4
call void @bar(i32 %0)
br label %for.header
for.header:
%1 = phi i32 [ %0, %for.preheader ], [ %.pre, %for.body.for.body_crit_edge ]
%i = phi i64 [ 0, %for.preheader ], [ %inc, %for.body.for.body_crit_edge ]
%arrayidx = getelementptr inbounds i32, ptr %A, i64 %i
call void @bar(i32 %1)
%inc = add nsw i64 %i, 1
br i1 true, label %for.body, label %for.body.for.body_crit_edge
for.body:
%cmp = call i1 @foo(i64 %i)
br i1 %cmp, label %for.body.for.body_crit_edge, label %for.end
for.body.for.body_crit_edge:
%arrayidx.phi.trans.insert = getelementptr inbounds i32, ptr %A, i64 %inc
%.pre = load i32, ptr %arrayidx.phi.trans.insert, align 4
br label %for.header
for.end:
ret void
}
; Check that loop unroll pass correctly handle loops with
; (1) multiple exiting blocks; and
; (2) loop latch is not an exiting block.
define void @test3(ptr noalias %A, i1 %cond) {
; CHECK-LABEL: @test3(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[A:%.*]], align 4
; CHECK-NEXT: call void @bar(i32 [[TMP0]])
; CHECK-NEXT: br label [[FOR_HEADER:%.*]]
; CHECK: for.header:
; CHECK-NEXT: call void @bar(i32 [[TMP0]])
; CHECK-NEXT: br i1 [[COND:%.*]], label [[FOR_BODY:%.*]], label [[FOR_END:%.*]]
; CHECK: for.body:
; CHECK-NEXT: br label [[FOR_BODY_FOR_BODY_CRIT_EDGE:%.*]]
; CHECK: for.body.for.body_crit_edge:
; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 1
; CHECK-NEXT: [[DOTPRE:%.*]] = load i32, ptr [[ARRAYIDX_PHI_TRANS_INSERT]], align 4
; CHECK-NEXT: call void @bar(i32 [[DOTPRE]])
; CHECK-NEXT: br i1 [[COND]], label [[FOR_BODY_1:%.*]], label [[FOR_END]]
; CHECK: for.body.1:
; CHECK-NEXT: br label [[FOR_BODY_FOR_BODY_CRIT_EDGE_1:%.*]]
; CHECK: for.body.for.body_crit_edge.1:
; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT_1:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 2
; CHECK-NEXT: [[DOTPRE_1:%.*]] = load i32, ptr [[ARRAYIDX_PHI_TRANS_INSERT_1]], align 4
; CHECK-NEXT: call void @bar(i32 [[DOTPRE_1]])
; CHECK-NEXT: br i1 [[COND]], label [[FOR_BODY_2:%.*]], label [[FOR_END]]
; CHECK: for.body.2:
; CHECK-NEXT: br label [[FOR_BODY_FOR_BODY_CRIT_EDGE_2:%.*]]
; CHECK: for.body.for.body_crit_edge.2:
; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT_2:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 3
; CHECK-NEXT: [[DOTPRE_2:%.*]] = load i32, ptr [[ARRAYIDX_PHI_TRANS_INSERT_2]], align 4
; CHECK-NEXT: call void @bar(i32 [[DOTPRE_2]])
; CHECK-NEXT: br i1 [[COND]], label [[FOR_BODY_3:%.*]], label [[FOR_END]]
; CHECK: for.body.3:
; CHECK-NEXT: br i1 false, label [[FOR_BODY_FOR_BODY_CRIT_EDGE_3:%.*]], label [[FOR_END]]
; CHECK: for.body.for.body_crit_edge.3:
; CHECK-NEXT: unreachable
; CHECK: for.end:
; CHECK-NEXT: ret void
;
entry:
%0 = load i32, ptr %A, align 4
call void @bar(i32 %0)
br label %for.header
for.header:
%1 = phi i32 [ %0, %entry ], [ %.pre, %for.body.for.body_crit_edge ]
%i = phi i64 [ 0, %entry ], [ %inc, %for.body.for.body_crit_edge ]
%arrayidx = getelementptr inbounds i32, ptr %A, i64 %i
call void @bar(i32 %1)
br i1 %cond, label %for.body, label %for.end
for.body:
%inc = add nsw i64 %i, 1
%cmp = icmp slt i64 %inc, 4
br i1 %cmp, label %for.body.for.body_crit_edge, label %for.end
for.body.for.body_crit_edge:
%arrayidx.phi.trans.insert = getelementptr inbounds i32, ptr %A, i64 %inc
%.pre = load i32, ptr %arrayidx.phi.trans.insert, align 4
br label %for.header
for.end:
ret void
}
; Test it doesn't crash.
define void @test4(i32 %arg) {
; CHECK-LABEL: @test4(
; CHECK-NEXT: bb:
; CHECK-NEXT: br label [[BB1:%.*]]
; CHECK: bb1:
; CHECK-NEXT: br i1 false, label [[BB4:%.*]], label [[BB1_1:%.*]]
; CHECK: bb1.1:
; CHECK-NEXT: br i1 false, label [[BB4]], label [[BB1_2:%.*]]
; CHECK: bb1.2:
; CHECK-NEXT: br i1 false, label [[BB4]], label [[BB1_3:%.*]]
; CHECK: bb1.3:
; CHECK-NEXT: br i1 false, label [[BB4]], label [[BB1]], !llvm.loop [[LOOP2:![0-9]+]]
; CHECK: bb4:
; CHECK-NEXT: unreachable
;
bb:
br label %bb1
bb1: ; preds = %bb1, %bb
%tmp = phi i64 [ 0, %bb ], [ 65, %bb1 ]
%tmp2 = phi i32 [ %arg, %bb ], [ %tmp3, %bb1 ]
%tmp3 = add i32 0, -1880031232
br i1 false, label %bb4, label %bb1
bb4: ; preds = %bb1
unreachable
}
declare void @bar(i32)
declare i1 @foo(i64)
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