e8918c318e
For the attached test: Before the loop-idiom pass, we have a store into the inner loop which is considered simple and one that does not have any side effects on the loop. Post loop-idiom pass, we get a memset into the outer loop that is considered to introduce side effects on the loop. This changes the backedge taken count before and after the pass and hence, the crash with verify-scev. We try to consider non-volatile memory intrinsics as not having side-effect for forward progress to fix the issue. Fixes #149377
48 lines
1.5 KiB
LLVM
48 lines
1.5 KiB
LLVM
; RUN: opt <%s -p "print<scalar-evolution>" -disable-output 2>&1 | FileCheck %s
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; RUN: opt <%s -p "loop(loop-idiom),print<scalar-evolution>" -disable-output 2>&1 | FileCheck %s
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; CHECK: backedge-taken count is i64 1
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; IR corresponds to the following C test:
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; extern char a[];
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; void foo() {
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; for (long c = 0; c < 6; c += -2078836808675943215)
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; for (long d; d < 6; d++)
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; a[c + d] = 0;
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; }
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@a = external global [0 x i8]
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define void @foo() {
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entry:
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br label %outerL
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outerL: ; preds = %entry, %outerLatch
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%e = phi i64 [ poison, %entry ], [ %lcssa, %outerLatch ]
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%c = phi i64 [ 0, %entry ], [ %c.next, %outerLatch ]
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%e.cmp = icmp slt i64 %e, 6
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br i1 %e.cmp, label %innerL, label %outerLatch
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innerL: ; preds = %outerL, %innerL
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%d = phi i64 [ %d.next, %innerL ], [ %e, %outerL ]
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%add = add nsw i64 %d, %c
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%arrayidx = getelementptr inbounds [0 x i8], ptr @a, i64 0, i64 %add
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store i8 0, ptr %arrayidx
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%d.next = add nsw i64 %d, 1
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%d.cmp = icmp slt i64 %d, 5
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br i1 %d.cmp, label %innerL, label %outerLatch, !llvm.loop !0
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outerLatch: ; preds = %innerL, %outerL
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%lcssa = phi i64 [ %e, %outerL ], [ %d.next, %innerL ]
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%c.next = add nsw i64 %c, -2078836808675943215
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%c.cmp = icmp slt i64 %c, 2078836808675943221
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br i1 %c.cmp, label %outerL, label %exit, !llvm.loop !1
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exit: ; preds = %outerLatch
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ret void
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}
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!0 = distinct !{!0, !2}
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!1 = distinct !{!1, !2}
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!2 = !{!"llvm.loop.mustprogress"}
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