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059733f666
Summary: Previously we used to return a bogus result, 0, for IR like `ashr %val, -1`. I've also added an assert checking that `ComputeNumSignBits` at least returns 1. That assert found an already checked in test case where we were returning a bad result for `ashr %val, -1`. Fixes PR32045. Reviewers: spatel, majnemer Reviewed By: spatel, majnemer Subscribers: efriedma, mcrosier, llvm-commits Differential Revision: https://reviews.llvm.org/D30311 llvm-svn: 296273
40 lines
1.0 KiB
LLVM
40 lines
1.0 KiB
LLVM
; RUN: opt -S -indvars < %s | FileCheck %s
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; This is not an IndVarSimplify bug, but the original symptom
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; manifested as one.
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define i32 @foo(i32 %a, i32 %b, i32 %c, i32* %sink) {
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; CHECK-LABEL: @foo(
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; CHECK: for.end:
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; CHECK-NEXT: [[SHR:%.*]] = ashr i32 %neg3, -1
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; CHECK-NEXT: [[SUB:%.*]] = sub nsw i32 0, [[SHR]]
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; CHECK-NEXT: [[SHR1:%.*]] = ashr i32 [[SUB]], [[B:%.*]]
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; CHECK-NEXT: [[NEG:%.*]] = xor i32 [[SHR1]], -1
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; CHECK-NEXT: store i32 [[NEG]], i32* %sink
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;
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entry:
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%tobool2 = icmp eq i32 %a, 0
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br i1 %tobool2, label %exit, label %preheader
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preheader:
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%neg3 = phi i32 [ %c, %entry ], [ %neg, %for.end ]
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br label %for
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for:
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%p = phi i32 [ %dec, %for ], [ 1, %preheader ]
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%cmp = icmp sgt i32 %p, -1
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%dec = add nsw i32 %p, -1
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br i1 %cmp, label %for, label %for.end
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for.end:
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%shr = ashr i32 %neg3, %p
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%sub = sub nsw i32 0, %shr
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%shr1 = ashr i32 %sub, %b
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%neg = xor i32 %shr1, -1
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store i32 %neg, i32* %sink
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br i1 false, label %exit, label %preheader
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exit:
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ret i32 0
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}
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