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[NFC][IRCE] Add unit test to show room for improvement #71506

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Nov 7, 2023
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[NFC][IRCE] Add unit test to show room for improvement #71506

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132 changes: 132 additions & 0 deletions llvm/test/Transforms/IRCE/compound-loop-bound.ll
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 3
; RUN: opt -passes=irce < %s -S | FileCheck %s

; if (K > 0 && M > 0)
; for (i = 0; i < min(K, M); i++) {...}
;
; TODO: Loop bounds are safe according to loop guards. IRCE is allowed.
define void @incrementing_loop(ptr %arr, ptr %len_ptr, i32 %K, i32 %M) {
; CHECK-LABEL: define void @incrementing_loop(
; CHECK-SAME: ptr [[ARR:%.*]], ptr [[LEN_PTR:%.*]], i32 [[K:%.*]], i32 [[M:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[LEN:%.*]] = load i32, ptr [[LEN_PTR]], align 4, !range [[RNG0:![0-9]+]]
; CHECK-NEXT: [[CHECK0:%.*]] = icmp sgt i32 [[K]], 0
; CHECK-NEXT: [[CHECK1:%.*]] = icmp sgt i32 [[M]], 0
; CHECK-NEXT: [[AND:%.*]] = and i1 [[CHECK0]], [[CHECK1]]
; CHECK-NEXT: br i1 [[AND]], label [[PREHEADER:%.*]], label [[EXIT:%.*]]
; CHECK: preheader:
; CHECK-NEXT: [[SMIN:%.*]] = call i32 @llvm.smin.i32(i32 [[K]], i32 [[M]])
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IDX:%.*]] = phi i32 [ 0, [[PREHEADER]] ], [ [[IDX_NEXT:%.*]], [[IN_BOUNDS:%.*]] ]
; CHECK-NEXT: [[IDX_NEXT]] = add i32 [[IDX]], 1
; CHECK-NEXT: [[GUARD:%.*]] = icmp slt i32 [[IDX]], [[LEN]]
; CHECK-NEXT: br i1 [[GUARD]], label [[IN_BOUNDS]], label [[OUT_OF_BOUNDS:%.*]]
; CHECK: in.bounds:
; CHECK-NEXT: [[ADDR:%.*]] = getelementptr i32, ptr [[ARR]], i32 [[IDX]]
; CHECK-NEXT: store i32 0, ptr [[ADDR]], align 4
; CHECK-NEXT: [[NEXT:%.*]] = icmp slt i32 [[IDX_NEXT]], [[SMIN]]
; CHECK-NEXT: br i1 [[NEXT]], label [[LOOP]], label [[EXIT_LOOPEXIT:%.*]]
; CHECK: out.of.bounds:
; CHECK-NEXT: ret void
; CHECK: exit.loopexit:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
%len = load i32, ptr %len_ptr, !range !0
%check0 = icmp sgt i32 %K, 0
%check1 = icmp sgt i32 %M, 0
%and = and i1 %check0, %check1
br i1 %and, label %preheader, label %exit

preheader:
%smin = call i32 @llvm.smin.i32(i32 %K, i32 %M)
br label %loop

loop:
%idx = phi i32 [ 0, %preheader ], [ %idx.next, %in.bounds ]
%idx.next = add i32 %idx, 1
%guard = icmp slt i32 %idx, %len
br i1 %guard, label %in.bounds, label %out.of.bounds

in.bounds:
%addr = getelementptr i32, ptr %arr, i32 %idx
store i32 0, ptr %addr
%next = icmp slt i32 %idx.next, %smin
br i1 %next, label %loop, label %exit

out.of.bounds:
ret void

exit:
ret void
}

; if (K > 0 && M > 0)
; for (i = min(K, M); i >= 0; i--) {...}
;
; TODO: Loop bounds are safe according to loop guards. IRCE is allowed.
define void @decrementing_loop(ptr %arr, ptr %len_ptr, i32 %K, i32 %M) {
; CHECK-LABEL: define void @decrementing_loop(
; CHECK-SAME: ptr [[ARR:%.*]], ptr [[LEN_PTR:%.*]], i32 [[K:%.*]], i32 [[M:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[LEN:%.*]] = load i32, ptr [[LEN_PTR]], align 4, !range [[RNG0]]
; CHECK-NEXT: [[CHECK0:%.*]] = icmp sgt i32 [[K]], 0
; CHECK-NEXT: [[CHECK1:%.*]] = icmp sgt i32 [[M]], 0
; CHECK-NEXT: [[AND:%.*]] = and i1 [[CHECK0]], [[CHECK1]]
; CHECK-NEXT: br i1 [[AND]], label [[PREHEADER:%.*]], label [[EXIT:%.*]]
; CHECK: preheader:
; CHECK-NEXT: [[SMIN:%.*]] = call i32 @llvm.smin.i32(i32 [[K]], i32 [[M]])
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IDX:%.*]] = phi i32 [ [[SMIN]], [[PREHEADER]] ], [ [[IDX_DEC:%.*]], [[IN_BOUNDS:%.*]] ]
; CHECK-NEXT: [[IDX_DEC]] = sub i32 [[IDX]], 1
; CHECK-NEXT: [[GUARD:%.*]] = icmp slt i32 [[IDX]], [[LEN]]
; CHECK-NEXT: br i1 [[GUARD]], label [[IN_BOUNDS]], label [[OUT_OF_BOUNDS:%.*]]
; CHECK: in.bounds:
; CHECK-NEXT: [[ADDR:%.*]] = getelementptr i32, ptr [[ARR]], i32 [[IDX]]
; CHECK-NEXT: store i32 0, ptr [[ADDR]], align 4
; CHECK-NEXT: [[NEXT:%.*]] = icmp sgt i32 [[IDX_DEC]], -1
; CHECK-NEXT: br i1 [[NEXT]], label [[LOOP]], label [[EXIT_LOOPEXIT:%.*]]
; CHECK: out.of.bounds:
; CHECK-NEXT: ret void
; CHECK: exit.loopexit:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
%len = load i32, ptr %len_ptr, !range !0
%check0 = icmp sgt i32 %K, 0
%check1 = icmp sgt i32 %M, 0
%and = and i1 %check0, %check1
br i1 %and, label %preheader, label %exit

preheader:
%smin = call i32 @llvm.smin.i32(i32 %K, i32 %M)
br label %loop

loop:
%idx = phi i32 [ %smin, %preheader ] , [ %idx.dec, %in.bounds ]
%idx.dec = sub i32 %idx, 1
%guard = icmp slt i32 %idx, %len
br i1 %guard, label %in.bounds, label %out.of.bounds

in.bounds:
%addr = getelementptr i32, ptr %arr, i32 %idx
store i32 0, ptr %addr
%next = icmp sgt i32 %idx.dec, -1
br i1 %next, label %loop, label %exit

out.of.bounds:
ret void

exit:
ret void
}

declare i32 @llvm.smin.i32(i32, i32)

!0 = !{i32 0, i32 2147483647}