2c3453afd2
If a direction vector with all `*` elements, like `[* * *]`, is present, it indicates that none of the loop pairs are legal to interchange. In such cases, continuing the analysis is meaningless. This patch introduces a check to detect such direction vectors and exits early when one is found. This slightly reduces compile time.
46 lines
1.4 KiB
LLVM
46 lines
1.4 KiB
LLVM
; RUN: opt < %s -passes=loop-interchange -pass-remarks-output=%t \
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; RUN: -disable-output
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; RUN: FileCheck -input-file %t %s
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;; In the following case, p0 and p1 may alias, so the direction vector must be [* *].
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;;
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;; void may_alias(float *p0, float *p1) {
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;; for (int i = 0; i < 4; i++)
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;; for (int j = 0; j < 4; j++)
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;; p0[4 * i + j] = p1[4 * j + i];
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;; }
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; CHECK: --- !Missed
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; CHECK-NEXT: Pass: loop-interchange
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; CHECK-NEXT: Name: Dependence
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; CHECK-NEXT: Function: may_alias
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; CHECK-NEXT: Args:
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; CHECK-NEXT: - String: All loops have dependencies in all directions.
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; CHECK-NEXT: ...
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define void @may_alias(ptr %p0, ptr %p1) {
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entry:
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br label %for.i.header
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for.i.header:
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%i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
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br label %for.j
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for.j:
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%j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
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%idx.0 = getelementptr inbounds [4 x [4 x float]], ptr %p0, i32 0, i32 %j, i32 %i
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%idx.1 = getelementptr inbounds [4 x [4 x float]], ptr %p1, i32 0, i32 %i, i32 %j
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%0 = load float, ptr %idx.0, align 4
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store float %0, ptr %idx.1, align 4
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%j.inc = add nuw nsw i32 %j, 1
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%cmp.j = icmp slt i32 %j.inc, 4
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br i1 %cmp.j, label %for.j, label %for.i.latch
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for.i.latch:
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%i.inc = add nuw nsw i32 %i, 1
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%cmp.i = icmp slt i32 %i.inc, 4
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br i1 %cmp.i, label %for.i.header, label %exit
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exit:
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ret void
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}
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