1; RUN: opt -loop-accesses -analyze < %s | FileCheck %s 2; RUN: opt -passes='require<scalar-evolution>,require<aa>,loop(print-access-info)' -disable-output < %s 2>&1 | FileCheck %s 3 4; The runtime memory check code and the access grouping 5; algorithm both assume that the start and end values 6; for an access range are ordered (start <= stop). 7; When generating checks for accesses with negative stride 8; we need to take this into account and swap the interval 9; ends. 10; 11; for (i = 0; i < 10000; i++) { 12; B[i] = A[15000 - i] * 3; 13; } 14 15target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128" 16target triple = "aarch64--linux-gnueabi" 17 18; CHECK: function 'f': 19; CHECK: (Low: (20000 + %a) High: (60000 + %a)<nsw>) 20 21@B = common global i32* null, align 8 22@A = common global i32* null, align 8 23 24define void @f() { 25entry: 26 %a = load i32*, i32** @A, align 8 27 %b = load i32*, i32** @B, align 8 28 br label %for.body 29 30for.body: ; preds = %for.body, %entry 31 %idx = phi i64 [ 0, %entry ], [ %add, %for.body ] 32 %negidx = sub i64 15000, %idx 33 34 %arrayidxA0 = getelementptr inbounds i32, i32* %a, i64 %negidx 35 %loadA0 = load i32, i32* %arrayidxA0, align 2 36 37 %res = mul i32 %loadA0, 3 38 39 %add = add nuw nsw i64 %idx, 1 40 41 %arrayidxB = getelementptr inbounds i32, i32* %b, i64 %idx 42 store i32 %res, i32* %arrayidxB, align 2 43 44 %exitcond = icmp eq i64 %idx, 10000 45 br i1 %exitcond, label %for.end, label %for.body 46 47for.end: ; preds = %for.body 48 ret void 49} 50 51; CHECK: function 'g': 52; When the stride is not constant, we are forced to do umin/umax to get 53; the interval limits. 54 55; for (i = 0; i < 10000; i++) { 56; B[i] = A[15000 - step * i] * 3; 57; } 58 59; Here it is not obvious what the limits are, since 'step' could be negative. 60 61; CHECK: Low: (-1 + (-1 * ((-60001 + (-1 * %a)) umax (-60001 + (40000 * %step) + (-1 * %a))))) 62; CHECK: High: ((60000 + %a)<nsw> umax (60000 + (-40000 * %step) + %a)) 63 64define void @g(i64 %step) { 65entry: 66 %a = load i32*, i32** @A, align 8 67 %b = load i32*, i32** @B, align 8 68 br label %for.body 69 70for.body: ; preds = %for.body, %entry 71 %idx = phi i64 [ 0, %entry ], [ %add, %for.body ] 72 %idx_mul = mul i64 %idx, %step 73 %negidx = sub i64 15000, %idx_mul 74 75 %arrayidxA0 = getelementptr inbounds i32, i32* %a, i64 %negidx 76 %loadA0 = load i32, i32* %arrayidxA0, align 2 77 78 %res = mul i32 %loadA0, 3 79 80 %add = add nuw nsw i64 %idx, 1 81 82 %arrayidxB = getelementptr inbounds i32, i32* %b, i64 %idx 83 store i32 %res, i32* %arrayidxB, align 2 84 85 %exitcond = icmp eq i64 %idx, 10000 86 br i1 %exitcond, label %for.end, label %for.body 87 88for.end: ; preds = %for.body 89 ret void 90} 91