forked from OSchip/llvm-project
101 lines
3.6 KiB
LLVM
101 lines
3.6 KiB
LLVM
; RUN: opt -bdce %s -S | FileCheck %s
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; The 'nuw' on the subtract allows us to deduce that %setbit is not demanded.
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; But if we change that value to '0', then the 'nuw' is no longer valid. If we don't
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; remove the 'nuw', another pass (-instcombine) may make a transform based on an
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; that incorrect assumption and we can miscompile:
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; https://bugs.llvm.org/show_bug.cgi?id=33695
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define i1 @PR33695(i1 %b, i8 %x) {
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; CHECK-LABEL: @PR33695(
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; CHECK-NEXT: [[SETBIT:%.*]] = or i8 %x, 64
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; CHECK-NEXT: [[LITTLE_NUMBER:%.*]] = zext i1 %b to i8
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; CHECK-NEXT: [[BIG_NUMBER:%.*]] = shl i8 0, 1
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; CHECK-NEXT: [[SUB:%.*]] = sub i8 [[BIG_NUMBER]], [[LITTLE_NUMBER]]
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; CHECK-NEXT: [[TRUNC:%.*]] = trunc i8 [[SUB]] to i1
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; CHECK-NEXT: ret i1 [[TRUNC]]
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;
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%setbit = or i8 %x, 64
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%little_number = zext i1 %b to i8
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%big_number = shl i8 %setbit, 1
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%sub = sub nuw i8 %big_number, %little_number
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%trunc = trunc i8 %sub to i1
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ret i1 %trunc
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}
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; Similar to above, but now with more no-wrap.
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; https://bugs.llvm.org/show_bug.cgi?id=34037
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define i64 @PR34037(i64 %m, i32 %r, i64 %j, i1 %b, i32 %k, i64 %p) {
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; CHECK-LABEL: @PR34037(
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; CHECK-NEXT: [[CONV:%.*]] = zext i32 %r to i64
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; CHECK-NEXT: [[AND:%.*]] = and i64 %m, 0
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; CHECK-NEXT: [[NEG:%.*]] = xor i64 0, 34359738367
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; CHECK-NEXT: [[OR:%.*]] = or i64 %j, 0
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; CHECK-NEXT: [[SHL:%.*]] = shl i64 0, 29
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; CHECK-NEXT: [[CONV1:%.*]] = select i1 %b, i64 7, i64 0
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; CHECK-NEXT: [[SUB:%.*]] = sub i64 [[SHL]], [[CONV1]]
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; CHECK-NEXT: [[CONV2:%.*]] = zext i32 %k to i64
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; CHECK-NEXT: [[MUL:%.*]] = mul i64 [[SUB]], [[CONV2]]
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; CHECK-NEXT: [[CONV4:%.*]] = and i64 %p, 65535
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; CHECK-NEXT: [[AND5:%.*]] = and i64 [[MUL]], [[CONV4]]
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; CHECK-NEXT: ret i64 [[AND5]]
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;
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%conv = zext i32 %r to i64
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%and = and i64 %m, %conv
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%neg = xor i64 %and, 34359738367
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%or = or i64 %j, %neg
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%shl = shl i64 %or, 29
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%conv1 = select i1 %b, i64 7, i64 0
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%sub = sub nuw nsw i64 %shl, %conv1
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%conv2 = zext i32 %k to i64
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%mul = mul nsw i64 %sub, %conv2
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%conv4 = and i64 %p, 65535
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%and5 = and i64 %mul, %conv4
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ret i64 %and5
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}
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; This is a manufactured example based on the 1st test to prove that the
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; assumption-killing algorithm stops at the call. Ie, it does not remove
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; nsw/nuw from the 'add' because a call demands all bits of its argument.
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declare i1 @foo(i1)
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define i1 @poison_on_call_user_is_ok(i1 %b, i8 %x) {
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; CHECK-LABEL: @poison_on_call_user_is_ok(
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; CHECK-NEXT: [[SETBIT:%.*]] = or i8 %x, 64
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; CHECK-NEXT: [[LITTLE_NUMBER:%.*]] = zext i1 %b to i8
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; CHECK-NEXT: [[BIG_NUMBER:%.*]] = shl i8 0, 1
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; CHECK-NEXT: [[SUB:%.*]] = sub i8 [[BIG_NUMBER]], [[LITTLE_NUMBER]]
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; CHECK-NEXT: [[TRUNC:%.*]] = trunc i8 [[SUB]] to i1
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; CHECK-NEXT: [[CALL_RESULT:%.*]] = call i1 @foo(i1 [[TRUNC]])
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; CHECK-NEXT: [[ADD:%.*]] = add nuw nsw i1 [[CALL_RESULT]], true
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; CHECK-NEXT: [[MUL:%.*]] = mul i1 [[TRUNC]], [[ADD]]
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; CHECK-NEXT: ret i1 [[MUL]]
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;
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%setbit = or i8 %x, 64
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%little_number = zext i1 %b to i8
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%big_number = shl i8 %setbit, 1
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%sub = sub nuw i8 %big_number, %little_number
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%trunc = trunc i8 %sub to i1
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%call_result = call i1 @foo(i1 %trunc)
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%add = add nsw nuw i1 %call_result, 1
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%mul = mul i1 %trunc, %add
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ret i1 %mul
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}
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; We were asserting that all users of a trivialized integer-type instruction were
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; also integer-typed, but that's too strong. The alloca has a pointer-type result.
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define void @PR34179(i32* %a) {
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; CHECK-LABEL: @PR34179(
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; CHECK-NEXT: [[T0:%.*]] = load volatile i32, i32* %a
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; CHECK-NEXT: ret void
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;
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%t0 = load volatile i32, i32* %a
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%vla = alloca i32, i32 %t0
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ret void
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}
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