forked from OSchip/llvm-project
108 lines
4.1 KiB
LLVM
108 lines
4.1 KiB
LLVM
; RUN: opt -basicaa -loop-accesses -analyze < %s | FileCheck %s
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target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
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; i and i + 1 can overflow in the following kernel:
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; void test1(unsigned long long x, int *a, int *b) {
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; for (unsigned i = 0; i < x; ++i)
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; b[i] = a[i+1] + 1;
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; }
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;
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; If accesses to a and b can alias, we need to emit a run-time alias check
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; between accesses to a and b. However, when i and i + 1 can wrap, their
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; SCEV expression is not an AddRec. We need to create SCEV predicates and
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; coerce the expressions to AddRecs in order to be able to emit the run-time
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; alias check.
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;
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; The accesses at b[i] and a[i+1] correspond to the addresses %arrayidx and
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; %arrayidx4 in the test. The SCEV expressions for these are:
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; ((4 * (zext i32 {1,+,1}<%for.body> to i64))<nuw><nsw> + %a)<nsw>
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; ((4 * (zext i32 {0,+,1}<%for.body> to i64))<nuw><nsw> + %b)<nsw>
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;
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; The transformed expressions are:
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; i64 {(4 + %a),+,4}<%for.body>
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; i64 {(4 + %b),+,4}<%for.body>
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; CHECK-LABEL: test1
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; CHECK: Memory dependences are safe with run-time checks
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; CHECK-NEXT: Dependences:
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; CHECK-NEXT: Run-time memory checks:
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; CHECK-NEXT: Check 0:
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; CHECK-NEXT: Comparing group
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; CHECK-NEXT: %arrayidx = getelementptr inbounds i32, i32* %a, i64 %idxprom
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; CHECK-NEXT: Against group
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; CHECK-NEXT: %arrayidx4 = getelementptr inbounds i32, i32* %b, i64 %conv11
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; CHECK-NEXT: Grouped accesses:
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; CHECK-NEXT: Group
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; CHECK-NEXT: (Low: (4 + %a) High: (4 + (4 * (1 umax %x)) + %a))
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; CHECK-NEXT: Member: {(4 + %a),+,4}<%for.body>
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; CHECK-NEXT: Group
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; CHECK-NEXT: (Low: %b High: ((4 * (1 umax %x)) + %b))
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; CHECK-NEXT: Member: {%b,+,4}<%for.body>
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; CHECK: Multiple stores to invariant address were not found in loop.
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; CHECK-NEXT: SCEV assumptions:
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; CHECK-NEXT: {1,+,1}<%for.body> Added Flags: <nusw>
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; CHECK-NEXT: {0,+,1}<%for.body> Added Flags: <nusw>
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; CHECK: Expressions re-written:
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; CHECK-NEXT: [PSE] %arrayidx = getelementptr inbounds i32, i32* %a, i64 %idxprom:
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; CHECK-NEXT: ((4 * (zext i32 {1,+,1}<%for.body> to i64))<nuw><nsw> + %a)<nsw>
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; CHECK-NEXT: --> {(4 + %a),+,4}<%for.body>
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; CHECK-NEXT: [PSE] %arrayidx4 = getelementptr inbounds i32, i32* %b, i64 %conv11:
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; CHECK-NEXT: ((4 * (zext i32 {0,+,1}<%for.body> to i64))<nuw><nsw> + %b)<nsw>
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; CHECK-NEXT: --> {%b,+,4}<%for.body>
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define void @test1(i64 %x, i32* %a, i32* %b) {
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entry:
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br label %for.body
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for.body: ; preds = %for.body.preheader, %for.body
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%conv11 = phi i64 [ %conv, %for.body ], [ 0, %entry ]
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%i.010 = phi i32 [ %add, %for.body ], [ 0, %entry ]
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%add = add i32 %i.010, 1
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%idxprom = zext i32 %add to i64
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%arrayidx = getelementptr inbounds i32, i32* %a, i64 %idxprom
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%ld = load i32, i32* %arrayidx, align 4
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%add2 = add nsw i32 %ld, 1
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%arrayidx4 = getelementptr inbounds i32, i32* %b, i64 %conv11
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store i32 %add2, i32* %arrayidx4, align 4
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%conv = zext i32 %add to i64
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%cmp = icmp ult i64 %conv, %x
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br i1 %cmp, label %for.body, label %exit
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exit:
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ret void
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}
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; i can overflow in the following kernel:
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; void test2(unsigned long long x, int *a) {
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; for (unsigned i = 0; i < x; ++i)
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; a[i] = a[i] + 1;
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; }
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;
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; We need to check that i doesn't wrap, but we don't need a run-time alias
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; check. We also need an extra no-wrap check to get the backedge taken count.
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; CHECK-LABEL: test2
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; CHECK: Memory dependences are safe
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; CHECK: SCEV assumptions:
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; CHECK-NEXT: {1,+,1}<%for.body> Added Flags: <nusw>
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; CHECK-NEXT: {0,+,1}<%for.body> Added Flags: <nusw>
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define void @test2(i64 %x, i32* %a) {
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entry:
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br label %for.body
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for.body:
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%conv11 = phi i64 [ %conv, %for.body ], [ 0, %entry ]
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%i.010 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
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%arrayidx = getelementptr inbounds i32, i32* %a, i64 %conv11
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%ld = load i32, i32* %arrayidx, align 4
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%add = add nsw i32 %ld, 1
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store i32 %add, i32* %arrayidx, align 4
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%inc = add i32 %i.010, 1
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%conv = zext i32 %inc to i64
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%cmp = icmp ult i64 %conv, %x
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br i1 %cmp, label %for.body, label %exit
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exit:
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ret void
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}
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