llvm-project/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll
David Sherwood 76f3776185
[NFC][LoopVectorize] Restructure simple early exit tests (#112721)
The previous simple_early_exit.ll was growing too large and difficult to
manage. Instead I've decided to refactor the tests by splitting out into
notional groups:

1. single_early_exit.ll: loops with a single uncountable exit that do
not have live-outs from the loop.
2. single_early_exit_live_outs.ll: loops with a single uncountable exit
with live-outs.
3. multi_early_exit.ll: loops with multiple early exits, i.e. a mixture
of countable and uncountable exits, but with no live-outs from the loop.
4. multi_early_exit_live_outs.ll: as above, but with live-outs.
5. single_early_exit_unsafe_ptrs.ll: loops with a single uncountable
exit, but with pointers that are not unconditionally dereferenceable.
6. unsupported_early_exit.ll: loops with uncountable exits that we
cannot yet vectorise.
7. early_exit_legality.ll: tests the debug output from
LoopVectorizationLegality to make sure we handle different scenarios
correctly.

Only the last test now requires asserts. Over time some of these tests
should start vectorising as more support is added.

I also tried to rename the multi early exit tests to make it clear there
what mixture of countable and uncountable exits are present.
2024-10-17 16:50:59 +01:00

543 lines
17 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
; REQUIRES: asserts
; RUN: opt -S < %s -p loop-vectorize -debug-only=loop-vectorize -disable-output 2>&1 | FileCheck %s
declare void @init_mem(ptr, i64);
; == SOME LEGAL EXAMPLES ==
; The form of the induction variables requires SCEV predicates.
define i32 @diff_exit_block_needs_scev_check(i32 %end) {
; CHECK-LABEL: LV: Checking a loop in 'diff_exit_block_needs_scev_check'
; CHECK: Found an early exit loop with symbolic max backedge taken count: (-1 + (1 umax (zext i10 (trunc i32 %end to i10) to i32)))<nsw>
; CHECK-NEXT: LV: We can vectorize this loop!
; CHECK-NEXT: LV: Not vectorizing: Auto-vectorization of loops with uncountable early exit is not yet supported.
entry:
%p1 = alloca [1024 x i32]
%p2 = alloca [1024 x i32]
call void @init_mem(ptr %p1, i64 1024)
call void @init_mem(ptr %p2, i64 1024)
%end.clamped = and i32 %end, 1023
br label %for.body
for.body:
%ind = phi i8 [ %ind.next, %for.inc ], [ 0, %entry ]
%gep.ind = phi i64 [ %gep.ind.next, %for.inc ], [ 0, %entry ]
%arrayidx1 = getelementptr inbounds i32, ptr %p1, i64 %gep.ind
%0 = load i32, ptr %arrayidx1, align 4
%arrayidx2 = getelementptr inbounds i32, ptr %p2, i64 %gep.ind
%1 = load i32, ptr %arrayidx2, align 4
%cmp.early = icmp eq i32 %0, %1
br i1 %cmp.early, label %found, label %for.inc
for.inc:
%ind.next = add i8 %ind, 1
%conv = zext i8 %ind.next to i32
%gep.ind.next = add i64 %gep.ind, 1
%cmp = icmp ult i32 %conv, %end.clamped
br i1 %cmp, label %for.body, label %exit
found:
ret i32 1
exit:
ret i32 0
}
define i64 @same_exit_block_pre_inc_use1() {
; CHECK-LABEL: LV: Checking a loop in 'same_exit_block_pre_inc_use1'
; CHECK: LV: Found an early exit loop with symbolic max backedge taken count: 63
; CHECK-NEXT: LV: We can vectorize this loop!
; CHECK-NEXT: LV: Not vectorizing: Auto-vectorization of loops with uncountable early exit is not yet supported.
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
call void @init_mem(ptr %p2, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
%ld1 = load i8, ptr %arrayidx, align 1
%arrayidx1 = getelementptr inbounds i8, ptr %p2, i64 %index
%ld2 = load i8, ptr %arrayidx1, align 1
%cmp3 = icmp eq i8 %ld1, %ld2
br i1 %cmp3, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
ret i64 %retval
}
define i64 @loop_contains_safe_call() {
; CHECK-LABEL: LV: Checking a loop in 'loop_contains_safe_call'
; CHECK: LV: Found an early exit loop with symbolic max backedge taken count: 63
; CHECK-NEXT: LV: We can vectorize this loop!
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
call void @init_mem(ptr %p2, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds float, ptr %p1, i64 %index
%ld1 = load float, ptr %arrayidx, align 1
%sqrt = tail call fast float @llvm.sqrt.f32(float %ld1)
%cmp = fcmp fast ult float %sqrt, 3.0e+00
br i1 %cmp, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
ret i64 %retval
}
define i64 @loop_contains_safe_div() {
; CHECK-LABEL: LV: Checking a loop in 'loop_contains_safe_div'
; CHECK: LV: Found an early exit loop with symbolic max backedge taken count: 63
; CHECK-NEXT: LV: We can vectorize this loop!
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
call void @init_mem(ptr %p2, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i32, ptr %p1, i64 %index
%ld1 = load i32, ptr %arrayidx, align 1
%div = udiv i32 %ld1, 20000
%cmp = icmp eq i32 %div, 1
br i1 %cmp, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
ret i64 %retval
}
define i64 @loop_contains_load_after_early_exit(ptr dereferenceable(1024) align(8) %p2) {
; CHECK-LABEL: LV: Checking a loop in 'loop_contains_load_after_early_exit'
; CHECK: LV: Found an early exit loop with symbolic max backedge taken count: 63
; CHECK-NEXT: LV: We can vectorize this loop!
; CHECK-NEXT: LV: Not vectorizing: Auto-vectorization of loops with uncountable early exit is not yet supported.
entry:
%p1 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i32, ptr %p1, i64 %index
%ld1 = load i32, ptr %arrayidx, align 1
%cmp = icmp eq i32 %ld1, 1
br i1 %cmp, label %loop.inc, label %loop.end
loop.inc:
%arrayidx2 = getelementptr inbounds i64, ptr %p2, i64 %index
%ld2 = load i64, ptr %arrayidx2, align 8
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop ], [ %ld2, %loop.inc ]
ret i64 %retval
}
; == SOME ILLEGAL EXAMPLES ==
define i64 @same_exit_block_pre_inc_use1_too_small_allocas() {
; CHECK-LABEL: LV: Checking a loop in 'same_exit_block_pre_inc_use1_too_small_allocas'
; CHECK: LV: Not vectorizing: Loop may fault.
entry:
%p1 = alloca [42 x i8]
%p2 = alloca [42 x i8]
call void @init_mem(ptr %p1, i64 1024)
call void @init_mem(ptr %p2, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
%ld1 = load i8, ptr %arrayidx, align 1
%arrayidx1 = getelementptr inbounds i8, ptr %p2, i64 %index
%ld2 = load i8, ptr %arrayidx1, align 1
%cmp3 = icmp eq i8 %ld1, %ld2
br i1 %cmp3, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
ret i64 %retval
}
define i64 @same_exit_block_pre_inc_use1_too_small_deref_ptrs(ptr dereferenceable(42) %p1, ptr dereferenceable(42) %p2) {
; CHECK-LABEL: LV: Checking a loop in 'same_exit_block_pre_inc_use1_too_small_deref_ptrs'
; CHECK: LV: Not vectorizing: Loop may fault.
entry:
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
%ld1 = load i8, ptr %arrayidx, align 1
%arrayidx1 = getelementptr inbounds i8, ptr %p2, i64 %index
%ld2 = load i8, ptr %arrayidx1, align 1
%cmp3 = icmp eq i8 %ld1, %ld2
br i1 %cmp3, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
ret i64 %retval
}
define i64 @same_exit_block_pre_inc_use1_unknown_ptrs(ptr %p1, ptr %p2) {
; CHECK-LABEL: LV: Checking a loop in 'same_exit_block_pre_inc_use1_unknown_ptrs'
; CHECK: LV: Not vectorizing: Loop may fault.
entry:
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
%ld1 = load i8, ptr %arrayidx, align 1
%arrayidx1 = getelementptr inbounds i8, ptr %p2, i64 %index
%ld2 = load i8, ptr %arrayidx1, align 1
%cmp3 = icmp eq i8 %ld1, %ld2
br i1 %cmp3, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
ret i64 %retval
}
; The early exit (i.e. unknown exit-not-taken count) is the latch - we don't
; support this yet.
define i64 @uncountable_exit_on_last_block() {
; CHECK-LABEL: LV: Checking a loop in 'uncountable_exit_on_last_block'
; CHECK: LV: Not vectorizing: Early exit is not the latch predecessor.
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
call void @init_mem(ptr %p2, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %search ], [ 3, %entry ]
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %search, label %loop.end
search:
%arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
%ld1 = load i8, ptr %arrayidx, align 1
%arrayidx1 = getelementptr inbounds i8, ptr %p2, i64 %index
%ld2 = load i8, ptr %arrayidx1, align 1
%cmp3 = icmp eq i8 %ld1, %ld2
br i1 %cmp3, label %loop.end, label %loop
loop.end:
%retval = phi i64 [ 64, %loop ], [ %index, %search ]
ret i64 %retval
}
; We don't currently support multiple uncountable early exits.
define i64 @multiple_uncountable_exits() {
; CHECK-LABEL: LV: Checking a loop in 'multiple_uncountable_exits'
; CHECK: LV: Not vectorizing: Loop has too many uncountable exits.
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
call void @init_mem(ptr %p2, i64 1024)
br label %search1
search1:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
%ld1 = load i8, ptr %arrayidx, align 1
%arrayidx1 = getelementptr inbounds i8, ptr %p2, i64 %index
%ld2 = load i8, ptr %arrayidx1, align 1
%cmp1 = icmp eq i8 %ld1, %ld2
br i1 %cmp1, label %loop.end, label %search2
search2:
%cmp2 = icmp ult i8 %ld1, 34
br i1 %cmp2, label %loop.end, label %loop.inc
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %search1, label %loop.end
loop.end:
%retval = phi i64 [ %index, %search1 ], [ 100, %search2 ], [ 43, %loop.inc ]
ret i64 %retval
}
define i64 @uncountable_exit_infinite_loop() {
; CHECK-LABEL: LV: Checking a loop in 'uncountable_exit_infinite_loop'
; CHECK: LV: Not vectorizing: Cannot determine exact exit count for latch block.
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
call void @init_mem(ptr %p2, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
%ld1 = load i8, ptr %arrayidx, align 1
%arrayidx1 = getelementptr inbounds i8, ptr %p2, i64 %index
%ld2 = load i8, ptr %arrayidx1, align 1
%cmp3 = icmp eq i8 %ld1, %ld2
br i1 %cmp3, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br label %loop
loop.end:
%retval = phi i64 [ %index, %loop ]
ret i64 %retval
}
define i64 @loop_contains_unsafe_call() {
; CHECK-LABEL: LV: Checking a loop in 'loop_contains_unsafe_call'
; CHECK: LV: Not vectorizing: Early exit loop contains operations that cannot be speculatively executed.
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
call void @init_mem(ptr %p2, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i32, ptr %p1, i64 %index
%ld1 = load i32, ptr %arrayidx, align 1
%bad_call = call i32 @foo(i32 %ld1) #0
%cmp = icmp eq i32 %bad_call, 34
br i1 %cmp, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
ret i64 %retval
}
define i64 @loop_contains_unsafe_div() {
; CHECK-LABEL: LV: Checking a loop in 'loop_contains_unsafe_div'
; CHECK: LV: Not vectorizing: Early exit loop contains operations that cannot be speculatively executed.
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
call void @init_mem(ptr %p2, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
%ld1 = load i32, ptr %arrayidx, align 1
%div = udiv i32 20000, %ld1
%cmp = icmp eq i32 %div, 1
br i1 %cmp, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
ret i64 %retval
}
define i64 @loop_contains_store(ptr %dest) {
; CHECK-LABEL: LV: Checking a loop in 'loop_contains_store'
; CHECK: LV: Not vectorizing: Writes to memory unsupported in early exit loops
entry:
%p1 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i32, ptr %p1, i64 %index
%ld1 = load i32, ptr %arrayidx, align 1
%arrayidx2 = getelementptr inbounds i32, ptr %dest, i64 %index
store i32 %ld1, ptr %arrayidx2, align 4
%cmp = icmp eq i32 %ld1, 1
br i1 %cmp, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
ret i64 %retval
}
define i64 @uncountable_exit_in_conditional_block(ptr %mask) {
; CHECK-LABEL: LV: Checking a loop in 'uncountable_exit_in_conditional_block'
; CHECK: LV: Not vectorizing: Early exit is not the latch predecessor.
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
call void @init_mem(ptr %p2, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx1 = getelementptr inbounds i8, ptr %mask, i64 %index
%ld1 = load i8, ptr %arrayidx1, align 1
%cmp1 = icmp ne i8 %ld1, 0
br i1 %cmp1, label %loop.search, label %loop.inc
loop.search:
%arrayidx2 = getelementptr inbounds i8, ptr %p1, i64 %index
%ld2 = load i8, ptr %arrayidx2, align 1
%arrayidx3 = getelementptr inbounds i8, ptr %p2, i64 %index
%ld3 = load i8, ptr %arrayidx3, align 1
%cmp2 = icmp eq i8 %ld2, %ld3
br i1 %cmp2, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop.search ], [ 67, %loop.inc ]
ret i64 %retval
}
define i64 @same_exit_block_pre_inc_use1_with_reduction() {
; CHECK-LABEL: LV: Checking a loop in 'same_exit_block_pre_inc_use1_with_reduction'
; CHECK: LV: Not vectorizing: Found reductions or recurrences in early-exit loop.
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
call void @init_mem(ptr %p2, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%red = phi i64 [ %red.next, %loop.inc ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
%ld1 = load i8, ptr %arrayidx, align 1
%arrayidx1 = getelementptr inbounds i8, ptr %p2, i64 %index
%ld2 = load i8, ptr %arrayidx1, align 1
%ld2.zext = zext i8 %ld2 to i64
%red.next = add i64 %red, %ld2.zext
%cmp3 = icmp eq i8 %ld1, %ld2
br i1 %cmp3, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%final.ind = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
%retval = add i64 %red.next, %final.ind
ret i64 %retval
}
define i64 @uncountable_exit_has_multiple_outside_successors() {
; CHECK-LABEL: LV: Checking a loop in 'uncountable_exit_has_multiple_outside_successors'
; CHECK: LV: Not vectorizing: Loop contains an unsupported switch
entry:
%p1 = alloca [1024 x i8]
call void @init_mem(ptr %p1, i64 1024)
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
%ld1 = load i8, ptr %arrayidx, align 1
switch i8 %ld1, label %loop.inc [
i8 2, label %loop.end
i8 3, label %loop.surprise
]
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.surprise:
ret i64 3
loop.end:
%retval = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
ret i64 %retval
}
declare i32 @foo(i32) readonly
declare <vscale x 4 x i32> @foo_vec(<vscale x 4 x i32>)
attributes #0 = { "vector-function-abi-variant"="_ZGVsNxv_foo(foo_vec)" }