efe4e7a026
SCEV currently preserves the nsw flag when performing an nsw multiply of an nsw addrec. While this is legal for nuw, this is not generally the case for nsw. This is because nsw mul does not distribute over nsw add: https://alive2.llvm.org/ce/z/mergCt Instead, we need either both nuw and nsw to be set (https://alive2.llvm.org/ce/z/7wpgGc) or explicitly prove that the distributed multiplications are also nsw (https://alive2.llvm.org/ce/z/wef9su). Fixes https://github.com/llvm/llvm-project/issues/66066.
35 lines
1009 B
LLVM
35 lines
1009 B
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 3
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; RUN: opt -S -passes=indvars < %s | FileCheck %s
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; The comparison should not get folded to false.
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define void @test() {
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; CHECK-LABEL: define void @test() {
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LOOP:%.*]]
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; CHECK: loop:
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; CHECK-NEXT: [[IV:%.*]] = phi i8 [ 1, [[ENTRY:%.*]] ], [ [[IV_DEC:%.*]], [[LOOP]] ]
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; CHECK-NEXT: [[IV_DEC]] = add nsw i8 [[IV]], -1
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; CHECK-NEXT: [[SHL:%.*]] = shl i8 [[IV]], 7
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; CHECK-NEXT: call void @use(i8 [[SHL]])
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; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i8 [[SHL]], 0
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; CHECK-NEXT: br i1 [[CMP1]], label [[EXIT:%.*]], label [[LOOP]]
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; CHECK: exit:
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; CHECK-NEXT: ret void
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;
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entry:
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br label %loop
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loop:
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%iv = phi i8 [ 1, %entry ], [ %iv.dec, %loop ]
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%iv.dec = add i8 %iv, -1
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%shl = shl i8 %iv, 7
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call void @use(i8 %shl)
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%cmp1 = icmp eq i8 %shl, 0
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br i1 %cmp1, label %exit, label %loop
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exit:
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ret void
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}
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declare void @use(i32)
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