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15c8d7c6d1
proven larger than the loop-count This fixes PR31098: Try to resolve statically data-dependences whose compile-time-unknown distance can be proven larger than the loop-count, instead of resorting to runtime dependence checking (which are not always possible). For vectorization it is sufficient to prove that the dependence distance is >= VF; But in some cases we can prune unknown dependence distances early, and even before selecting the VF, and without a runtime test, by comparing the distance against the loop iteration count. Since the vectorized code will be executed only if LoopCount >= VF, proving distance >= LoopCount also guarantees that distance >= VF. This check is also equivalent to the Strong SIV Test. Reviewers: mkuper, anemet, sanjoy Differential Revision: https://reviews.llvm.org/D28044 llvm-svn: 294892
69 lines
2.0 KiB
LLVM
69 lines
2.0 KiB
LLVM
; RUN: opt -loop-accesses -analyze -S < %s | FileCheck %s
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; RUN: opt -passes='require<scalar-evolution>,require<aa>,loop(print-access-info)' -disable-output < %s 2>&1 | FileCheck %s
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; This is the test case from PR26314.
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; When we were retrying dependence checking with memchecks only,
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; the loop-invariant access in the inner loop was incorrectly determined to be wrapping
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; because it was not strided in the inner loop.
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; #define Z 32
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; typedef struct s {
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; int v1[Z];
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; int v2[Z];
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; int v3[Z][Z];
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; } s;
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;
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; void slow_function (s* const obj, int z) {
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; for (int j=0; j<Z; j++) {
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; for (int k=0; k<z; k++) {
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; int x = obj->v1[k] + obj->v2[j];
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; obj->v3[j][k] += x;
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; }
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; }
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; }
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; CHECK: function 'Test':
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; CHECK: .inner:
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; CHECK-NEXT: Memory dependences are safe
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; CHECK-NEXT: Dependences:
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; CHECK-NEXT: Run-time memory checks:
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; CHECK: Check 0:
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; CHECK: Check 1:
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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%struct.s = type { [32 x i32], [32 x i32], [32 x [32 x i32]] }
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define void @Test(%struct.s* nocapture %obj, i64 %z) #0 {
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br label %.outer.preheader
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.outer.preheader:
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%i = phi i64 [ 0, %0 ], [ %i.next, %.outer ]
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%1 = getelementptr inbounds %struct.s, %struct.s* %obj, i64 0, i32 1, i64 %i
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br label %.inner
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.exit:
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ret void
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.outer:
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%i.next = add nuw nsw i64 %i, 1
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%exitcond.outer = icmp eq i64 %i.next, 32
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br i1 %exitcond.outer, label %.exit, label %.outer.preheader
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.inner:
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%j = phi i64 [ 0, %.outer.preheader ], [ %j.next, %.inner ]
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%2 = getelementptr inbounds %struct.s, %struct.s* %obj, i64 0, i32 0, i64 %j
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%3 = load i32, i32* %2
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%4 = load i32, i32* %1
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%5 = add nsw i32 %4, %3
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%6 = getelementptr inbounds %struct.s, %struct.s* %obj, i64 0, i32 2, i64 %i, i64 %j
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%7 = load i32, i32* %6
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%8 = add nsw i32 %5, %7
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store i32 %8, i32* %6
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%j.next = add nuw nsw i64 %j, 1
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%exitcond.inner = icmp eq i64 %j.next, %z
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br i1 %exitcond.inner, label %.outer, label %.inner
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}
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