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[SCEV] Add additional max BTC tests with loop guards.
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@fhahn
fhahn committed Sep 21, 2020
1 parent 024979b commit 3cbdfe4
Showing 1 changed file with 244 additions and 2 deletions.
246 changes: 244 additions & 2 deletions llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info.ll
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Expand Up @@ -24,12 +24,189 @@ exit:
ret void
}

define void @test_guard_less_than_16_branches_flipped(i32* nocapture %a, i64 %i) {
; CHECK-LABEL: Determining loop execution counts for: @test_guard_less_than_16_branches_flipped
; CHECK-NEXT: Loop %loop: backedge-taken count is (15 + (-1 * %i))
; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (15 + (-1 * %i))
;
entry:
%cmp3 = icmp ult i64 %i, 16
br i1 %cmp3, label %exit, label %loop

loop:
%iv = phi i64 [ %iv.next, %loop ], [ %i, %entry ]
%idx = getelementptr inbounds i32, i32* %a, i64 %iv
store i32 1, i32* %idx, align 4
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv.next, 16
br i1 %exitcond, label %exit, label %loop

exit:
ret void
}

define void @test_guard_uge_16_branches_flipped(i32* nocapture %a, i64 %i) {
; CHECK-LABEL: Determining loop execution counts for: @test_guard_uge_16_branches_flipped
; CHECK-NEXT: Loop %loop: backedge-taken count is (15 + (-1 * %i))
; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (15 + (-1 * %i))
;
entry:
%cmp3 = icmp uge i64 %i, 16
br i1 %cmp3, label %exit, label %loop

loop:
%iv = phi i64 [ %iv.next, %loop ], [ %i, %entry ]
%idx = getelementptr inbounds i32, i32* %a, i64 %iv
store i32 1, i32* %idx, align 4
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv.next, 16
br i1 %exitcond, label %exit, label %loop

exit:
ret void
}

define void @test_multiple_const_guards_order1(i32* nocapture %a, i64 %i) {
; CHECK-LABEL: @test_multiple_const_guards_order1
; CHECK: Loop %loop: backedge-taken count is %i
; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %i
;
entry:
%c.1 = icmp ult i64 %i, 16
br i1 %c.1, label %guardbb, label %exit

guardbb:
%c.2 = icmp ult i64 %i, 10
br i1 %c.2, label %loop, label %exit

loop:
%iv = phi i64 [ %iv.next, %loop ], [ 0, %guardbb ]
%idx = getelementptr inbounds i32, i32* %a, i64 %iv
store i32 1, i32* %idx, align 4
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv, %i
br i1 %exitcond, label %exit, label %loop

exit:
ret void
}

define void @test_multiple_const_guards_order2(i32* nocapture %a, i64 %i) {
; CHECK-LABEL: @test_multiple_const_guards_order2
; CHECK: Loop %loop: backedge-taken count is %i
; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %i
;
entry:
%c.1 = icmp ult i64 %i, 10
br i1 %c.1, label %guardbb, label %exit

guardbb:
%c.2 = icmp ult i64 %i, 16
br i1 %c.2, label %loop, label %exit

loop:
%iv = phi i64 [ %iv.next, %loop ], [ 0, %guardbb ]
%idx = getelementptr inbounds i32, i32* %a, i64 %iv
store i32 1, i32* %idx, align 4
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv, %i
br i1 %exitcond, label %exit, label %loop

exit:
ret void
}

; TODO: Currently we miss getting the tightest max backedge-taken count (11).
define void @test_multiple_var_guards_order1(i32* nocapture %a, i64 %i, i64 %N) {
; CHECK-LABEL: @test_multiple_var_guards_order1
; CHECK: Loop %loop: backedge-taken count is %i
; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %i
;
entry:
%c.1 = icmp ult i64 %N, 12
br i1 %c.1, label %guardbb, label %exit

guardbb:
%c.2 = icmp ult i64 %i, %N
br i1 %c.2, label %loop, label %exit

loop:
%iv = phi i64 [ %iv.next, %loop ], [ 0, %guardbb ]
%idx = getelementptr inbounds i32, i32* %a, i64 %iv
store i32 1, i32* %idx, align 4
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv, %i
br i1 %exitcond, label %exit, label %loop

exit:
ret void
}

; TODO: Currently we miss getting the tightest max backedge-taken count (11).
define void @test_multiple_var_guards_order2(i32* nocapture %a, i64 %i, i64 %N) {
; CHECK-LABEL: Determining loop execution counts for: @test_multiple_var_guards_order2
; CHECK-NEXT: Loop %loop: backedge-taken count is %i
; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %i
;
entry:
%c.1 = icmp ult i64 %i, %N
br i1 %c.1, label %guardbb, label %exit

guardbb:
%c.2 = icmp ult i64 %N, 12
br i1 %c.2, label %loop, label %exit

loop:
%iv = phi i64 [ %iv.next, %loop ], [ 0, %guardbb ]
%idx = getelementptr inbounds i32, i32* %a, i64 %iv
store i32 1, i32* %idx, align 4
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv, %i
br i1 %exitcond, label %exit, label %loop

exit:
ret void
}

; The guards here reference each other in a cycle.
define void @test_multiple_var_guards_cycle(i32* nocapture %a, i64 %i, i64 %N) {
; CHECK-LABEL: Determining loop execution counts for: @test_multiple_var_guards_cycle
; CHECK-NEXT: Loop %loop: backedge-taken count is %N
; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %N
;
entry:
%c.1 = icmp ult i64 %N, %i
br i1 %c.1, label %guardbb, label %exit

guardbb:
%c.2 = icmp ult i64 %i, %N
br i1 %c.2, label %loop, label %exit

loop:
%iv = phi i64 [ %iv.next, %loop ], [ 0, %guardbb ]
%idx = getelementptr inbounds i32, i32* %a, i64 %iv
store i32 1, i32* %idx, align 4
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv, %N
br i1 %exitcond, label %exit, label %loop

exit:
ret void
}

; Test case for PR47247. Both the guard condition and the assume limit the
; max backedge-taken count.

define void @test_guard_and_assume(i32* nocapture readonly %data, i64 %count) {
; CHECK-LABEL: Determining loop execution counts for: @test_guard_and_assume
; CHECK-NEXT: Loop %loop: backedge-taken count is (-1 + %count)
; CHECK-LABEL: @test_guard_and_assume
; CHECK: Loop %loop: backedge-taken count is (-1 + %count)
; CHECK-NEXT: Loop %loop: max backedge-taken count is -2
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (-1 + %count)
;
Expand All @@ -53,3 +230,68 @@ exit:

; Function Attrs: nounwind willreturn
declare void @llvm.assume(i1 noundef)

define void @guard_pessimizes_analysis(i1 %c, i32 %N) {
; CHECK-LABEL: @guard_pessimizes_analysis
; CHECK: Loop %loop: backedge-taken count is (9 + (-1 * %init)<nsw>)<nsw>
; CHECK-NEXT: Loop %loop: max backedge-taken count is 7
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (9 + (-1 * %init)<nsw>)<nsw>
;
entry:
br i1 %c, label %bb1, label %guard

bb1:
br label %guard

guard:
%init = phi i32 [ 2, %entry ], [ 3, %bb1 ]
%c.1 = icmp ult i32 %init, %N
br i1 %c.1, label %loop.ph, label %exit

loop.ph:
br label %loop

loop:
%iv = phi i32 [ %iv.next, %loop ], [ %init, %loop.ph ]
%iv.next = add i32 %iv, 1
%exitcond = icmp eq i32 %iv.next, 10
br i1 %exitcond, label %exit, label %loop

exit:
ret void
}

define void @crash(i8* %ptr) {
; CHECK-LABEL: @crash
; CHECK: Loop %while.body125: backedge-taken count is {(-2 + (-1 * %ptr)),+,-1}<nw><%while.cond111>
; CHECK-NEXT: Loop %while.body125: max backedge-taken count is -1
; CHECK-NEXT: Loop %while.body125: Predicated backedge-taken count is {(-2 + (-1 * %ptr)),+,-1}<nw><%while.cond111>
;
entry:
br label %while.body

while.body:
br label %while.cond111

while.cond111:
%text.addr.5 = phi i8* [ %incdec.ptr112, %while.cond111 ], [ null, %while.body ]
%incdec.ptr112 = getelementptr inbounds i8, i8* %text.addr.5, i64 -1
br i1 false, label %while.end117, label %while.cond111

while.end117:
%cmp118 = icmp ult i8* %ptr, %incdec.ptr112
br i1 %cmp118, label %while.body125, label %while.cond134.preheader


while.cond134.preheader:
br label %while.body

while.body125:
%lastout.2271 = phi i8* [ %incdec.ptr126, %while.body125 ], [ %ptr, %while.end117 ]
%incdec.ptr126 = getelementptr inbounds i8, i8* %lastout.2271, i64 1
%exitcond.not = icmp eq i8* %incdec.ptr126, %incdec.ptr112
br i1 %exitcond.not, label %while.end129, label %while.body125

while.end129: ; preds = %while.body125
ret void
}

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