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llvm-mirror/test/Analysis/LoopAccessAnalysis/number-of-memchecks.ll
Nikita Popov 318f4a3446 [SCEV] Fix nsw flags for GEP expressions
The SCEV code for constructing GEP expressions currently assumes
that the addition of the base and all the offsets is nsw if the GEP
is inbounds. While the addition of the offsets is indeed nsw, the
addition to the base address is not, as the base address is
interpreted as an unsigned value.

Fix the GEP expression code to not assume nsw for the base+offset
calculation. However, do assume nuw if we know that the offset is
non-negative. With this, we use the same behavior as the
construction of GEP addrecs does. (Modulo the fact that we
disregard SCEV unification, as the pre-existing FIXME points out).

Differential Revision: https://reviews.llvm.org/D90648
2020-11-13 18:19:32 +01:00

289 lines
10 KiB
LLVM

; RUN: opt -loop-accesses -analyze -enable-new-pm=0 < %s | FileCheck %s
; RUN: opt -passes='require<scalar-evolution>,require<aa>,loop(print-access-info)' -disable-output < %s 2>&1 | FileCheck %s
target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
target triple = "aarch64--linux-gnueabi"
; 3 reads and 3 writes should need 12 memchecks
; CHECK: function 'testf':
; CHECK: Memory dependences are safe with run-time checks
; Memory dependencies have labels starting from 0, so in
; order to verify that we have n checks, we look for
; (n-1): and not n:.
; CHECK: Run-time memory checks:
; CHECK-NEXT: Check 0:
; CHECK: Check 11:
; CHECK-NOT: Check 12:
define void @testf(i16* %a,
i16* %b,
i16* %c,
i16* %d,
i16* %e,
i16* %f) {
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%ind = phi i64 [ 0, %entry ], [ %add, %for.body ]
%add = add nuw nsw i64 %ind, 1
%arrayidxA = getelementptr inbounds i16, i16* %a, i64 %ind
%loadA = load i16, i16* %arrayidxA, align 2
%arrayidxB = getelementptr inbounds i16, i16* %b, i64 %ind
%loadB = load i16, i16* %arrayidxB, align 2
%arrayidxC = getelementptr inbounds i16, i16* %c, i64 %ind
%loadC = load i16, i16* %arrayidxC, align 2
%mul = mul i16 %loadB, %loadA
%mul1 = mul i16 %mul, %loadC
%arrayidxD = getelementptr inbounds i16, i16* %d, i64 %ind
store i16 %mul1, i16* %arrayidxD, align 2
%arrayidxE = getelementptr inbounds i16, i16* %e, i64 %ind
store i16 %mul, i16* %arrayidxE, align 2
%arrayidxF = getelementptr inbounds i16, i16* %f, i64 %ind
store i16 %mul1, i16* %arrayidxF, align 2
%exitcond = icmp eq i64 %add, 20
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}
; The following (testg and testh) check that we can group
; memory checks of accesses which differ by a constant value.
; Both tests are based on the following C code:
;
; void testh(short *a, short *b, short *c) {
; unsigned long ind = 0;
; for (unsigned long ind = 0; ind < 20; ++ind) {
; c[2 * ind] = a[ind] * a[ind + 1];
; c[2 * ind + 1] = a[ind] * a[ind + 1] * b[ind];
; }
; }
;
; It is sufficient to check the intervals
; [a, a + 21], [b, b + 20] against [c, c + 41].
; 3 reads and 2 writes - two of the reads can be merged,
; and the writes can be merged as well. This gives us a
; total of 2 memory checks.
; CHECK: function 'testg':
; CHECK: Run-time memory checks:
; CHECK-NEXT: Check 0:
; CHECK-NEXT: Comparing group ([[ZERO:.+]]):
; CHECK-NEXT: %arrayidxC1 = getelementptr inbounds i16, i16* %c, i64 %store_ind_inc
; CHECK-NEXT: %arrayidxC = getelementptr inbounds i16, i16* %c, i64 %store_ind
; CHECK-NEXT: Against group ([[ONE:.+]]):
; CHECK-NEXT: %arrayidxA1 = getelementptr inbounds i16, i16* %a, i64 %add
; CHECK-NEXT: %arrayidxA = getelementptr inbounds i16, i16* %a, i64 %ind
; CHECK-NEXT: Check 1:
; CHECK-NEXT: Comparing group ({{.*}}[[ZERO]]):
; CHECK-NEXT: %arrayidxC1 = getelementptr inbounds i16, i16* %c, i64 %store_ind_inc
; CHECK-NEXT: %arrayidxC = getelementptr inbounds i16, i16* %c, i64 %store_ind
; CHECK-NEXT: Against group ([[TWO:.+]]):
; CHECK-NEXT: %arrayidxB = getelementptr inbounds i16, i16* %b, i64 %ind
; CHECK-NEXT: Grouped accesses:
; CHECK-NEXT: Group {{.*}}[[ZERO]]:
; CHECK-NEXT: (Low: %c High: (80 + %c))
; CHECK-NEXT: Member: {(2 + %c)<nuw>,+,4}
; CHECK-NEXT: Member: {%c,+,4}
; CHECK-NEXT: Group {{.*}}[[ONE]]:
; CHECK-NEXT: (Low: %a High: (42 + %a))
; CHECK-NEXT: Member: {(2 + %a)<nuw>,+,2}
; CHECK-NEXT: Member: {%a,+,2}
; CHECK-NEXT: Group {{.*}}[[TWO]]:
; CHECK-NEXT: (Low: %b High: (40 + %b))
; CHECK-NEXT: Member: {%b,+,2}
define void @testg(i16* %a,
i16* %b,
i16* %c) {
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%ind = phi i64 [ 0, %entry ], [ %add, %for.body ]
%store_ind = phi i64 [ 0, %entry ], [ %store_ind_next, %for.body ]
%add = add nuw nsw i64 %ind, 1
%store_ind_inc = add nuw nsw i64 %store_ind, 1
%store_ind_next = add nuw nsw i64 %store_ind_inc, 1
%arrayidxA = getelementptr inbounds i16, i16* %a, i64 %ind
%loadA = load i16, i16* %arrayidxA, align 2
%arrayidxA1 = getelementptr inbounds i16, i16* %a, i64 %add
%loadA1 = load i16, i16* %arrayidxA1, align 2
%arrayidxB = getelementptr inbounds i16, i16* %b, i64 %ind
%loadB = load i16, i16* %arrayidxB, align 2
%mul = mul i16 %loadA, %loadA1
%mul1 = mul i16 %mul, %loadB
%arrayidxC = getelementptr inbounds i16, i16* %c, i64 %store_ind
store i16 %mul1, i16* %arrayidxC, align 2
%arrayidxC1 = getelementptr inbounds i16, i16* %c, i64 %store_ind_inc
store i16 %mul, i16* %arrayidxC1, align 2
%exitcond = icmp eq i64 %add, 20
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}
; 3 reads and 2 writes - the writes can be merged into a single
; group, but the GEPs used for the reads are not marked as inbounds.
; We can still merge them because we are using a unit stride for
; accesses, so we cannot overflow the GEPs.
; CHECK: function 'testh':
; CHECK: Run-time memory checks:
; CHECK-NEXT: Check 0:
; CHECK-NEXT: Comparing group ([[ZERO:.+]]):
; CHECK-NEXT: %arrayidxC1 = getelementptr inbounds i16, i16* %c, i64 %store_ind_inc
; CHECK-NEXT: %arrayidxC = getelementptr inbounds i16, i16* %c, i64 %store_ind
; CHECK-NEXT: Against group ([[ONE:.+]]):
; CHECK-NEXT: %arrayidxA1 = getelementptr i16, i16* %a, i64 %add
; CHECK-NEXT: %arrayidxA = getelementptr i16, i16* %a, i64 %ind
; CHECK-NEXT: Check 1:
; CHECK-NEXT: Comparing group ({{.*}}[[ZERO]]):
; CHECK-NEXT: %arrayidxC1 = getelementptr inbounds i16, i16* %c, i64 %store_ind_inc
; CHECK-NEXT: %arrayidxC = getelementptr inbounds i16, i16* %c, i64 %store_ind
; CHECK-NEXT: Against group ([[TWO:.+]]):
; CHECK-NEXT: %arrayidxB = getelementptr i16, i16* %b, i64 %ind
; CHECK-NEXT: Grouped accesses:
; CHECK-NEXT: Group {{.*}}[[ZERO]]:
; CHECK-NEXT: (Low: %c High: (80 + %c))
; CHECK-NEXT: Member: {(2 + %c)<nuw>,+,4}
; CHECK-NEXT: Member: {%c,+,4}
; CHECK-NEXT: Group {{.*}}[[ONE]]:
; CHECK-NEXT: (Low: %a High: (42 + %a))
; CHECK-NEXT: Member: {(2 + %a),+,2}
; CHECK-NEXT: Member: {%a,+,2}
; CHECK-NEXT: Group {{.*}}[[TWO]]:
; CHECK-NEXT: (Low: %b High: (40 + %b))
; CHECK-NEXT: Member: {%b,+,2}
define void @testh(i16* %a,
i16* %b,
i16* %c) {
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%ind = phi i64 [ 0, %entry ], [ %add, %for.body ]
%store_ind = phi i64 [ 0, %entry ], [ %store_ind_next, %for.body ]
%add = add nuw nsw i64 %ind, 1
%store_ind_inc = add nuw nsw i64 %store_ind, 1
%store_ind_next = add nuw nsw i64 %store_ind_inc, 1
%arrayidxA = getelementptr i16, i16* %a, i64 %ind
%loadA = load i16, i16* %arrayidxA, align 2
%arrayidxA1 = getelementptr i16, i16* %a, i64 %add
%loadA1 = load i16, i16* %arrayidxA1, align 2
%arrayidxB = getelementptr i16, i16* %b, i64 %ind
%loadB = load i16, i16* %arrayidxB, align 2
%mul = mul i16 %loadA, %loadA1
%mul1 = mul i16 %mul, %loadB
%arrayidxC = getelementptr inbounds i16, i16* %c, i64 %store_ind
store i16 %mul1, i16* %arrayidxC, align 2
%arrayidxC1 = getelementptr inbounds i16, i16* %c, i64 %store_ind_inc
store i16 %mul, i16* %arrayidxC1, align 2
%exitcond = icmp eq i64 %add, 20
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}
; Don't merge pointers if we need to perform a check against a pointer
; to the same underlying object (doing so would emit a check that could be
; falsely invalidated) For example, in the following loop:
;
; for (i = 0; i < 5000; ++i)
; a[i + offset] = a[i] + a[i + 10000]
;
; we should not merge the intervals associated with the reads (0,5000) and
; (10000, 15000) into (0, 15000) as this will pottentially fail the check
; against the interval associated with the write.
;
; We cannot have this check unless ShouldRetryWithRuntimeCheck is set,
; and therefore the grouping algorithm would create a separate group for
; each pointer.
; CHECK: function 'testi':
; CHECK: Run-time memory checks:
; CHECK-NEXT: Check 0:
; CHECK-NEXT: Comparing group ([[ZERO:.+]]):
; CHECK-NEXT: %storeidx = getelementptr inbounds i16, i16* %a, i64 %store_ind
; CHECK-NEXT: Against group ([[ONE:.+]]):
; CHECK-NEXT: %arrayidxA1 = getelementptr i16, i16* %a, i64 %ind
; CHECK-NEXT: Check 1:
; CHECK-NEXT: Comparing group ({{.*}}[[ZERO]]):
; CHECK-NEXT: %storeidx = getelementptr inbounds i16, i16* %a, i64 %store_ind
; CHECK-NEXT: Against group ([[TWO:.+]]):
; CHECK-NEXT: %arrayidxA2 = getelementptr i16, i16* %a, i64 %ind2
; CHECK-NEXT: Grouped accesses:
; CHECK-NEXT: Group {{.*}}[[ZERO]]:
; CHECK-NEXT: (Low: ((2 * %offset) + %a) High: (10000 + (2 * %offset) + %a))
; CHECK-NEXT: Member: {((2 * %offset) + %a),+,2}<nw><%for.body>
; CHECK-NEXT: Group {{.*}}[[ONE]]:
; CHECK-NEXT: (Low: %a High: (10000 + %a))
; CHECK-NEXT: Member: {%a,+,2}<nw><%for.body>
; CHECK-NEXT: Group {{.*}}[[TWO]]:
; CHECK-NEXT: (Low: (20000 + %a) High: (30000 + %a))
; CHECK-NEXT: Member: {(20000 + %a),+,2}<nw><%for.body>
define void @testi(i16* %a,
i64 %offset) {
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%ind = phi i64 [ 0, %entry ], [ %add, %for.body ]
%store_ind = phi i64 [ %offset, %entry ], [ %store_ind_inc, %for.body ]
%add = add nuw nsw i64 %ind, 1
%store_ind_inc = add nuw nsw i64 %store_ind, 1
%arrayidxA1 = getelementptr i16, i16* %a, i64 %ind
%ind2 = add nuw nsw i64 %ind, 10000
%arrayidxA2 = getelementptr i16, i16* %a, i64 %ind2
%loadA1 = load i16, i16* %arrayidxA1, align 2
%loadA2 = load i16, i16* %arrayidxA2, align 2
%addres = add i16 %loadA1, %loadA2
%storeidx = getelementptr inbounds i16, i16* %a, i64 %store_ind
store i16 %addres, i16* %storeidx, align 2
%exitcond = icmp eq i64 %add, 5000
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}