1 ; RUN: opt -bdce %s -S | FileCheck %s 2 3 ; The 'nuw' on the subtract allows us to deduce that %setbit is not demanded. 4 ; But if we change that value to '0', then the 'nuw' is no longer valid. If we don't 5 ; remove the 'nuw', another pass (-instcombine) may make a transform based on an 6 ; that incorrect assumption and we can miscompile: 7 ; https://bugs.llvm.org/show_bug.cgi?id=33695 8 9 define i1 @PR33695(i1 %b, i8 %x) { 10 ; CHECK-LABEL: @PR33695( 11 ; CHECK-NEXT: [[SETBIT:%.*]] = or i8 %x, 64 12 ; CHECK-NEXT: [[LITTLE_NUMBER:%.*]] = zext i1 %b to i8 13 ; CHECK-NEXT: [[BIG_NUMBER:%.*]] = shl i8 0, 1 14 ; CHECK-NEXT: [[SUB:%.*]] = sub i8 [[BIG_NUMBER]], [[LITTLE_NUMBER]] 15 ; CHECK-NEXT: [[TRUNC:%.*]] = trunc i8 [[SUB]] to i1 16 ; CHECK-NEXT: ret i1 [[TRUNC]] 17 ; 18 %setbit = or i8 %x, 64 19 %little_number = zext i1 %b to i8 20 %big_number = shl i8 %setbit, 1 21 %sub = sub nuw i8 %big_number, %little_number 22 %trunc = trunc i8 %sub to i1 23 ret i1 %trunc 24 } 25 26 ; Similar to above, but now with more no-wrap. 27 ; https://bugs.llvm.org/show_bug.cgi?id=34037 28 29 define i64 @PR34037(i64 %m, i32 %r, i64 %j, i1 %b, i32 %k, i64 %p) { 30 ; CHECK-LABEL: @PR34037( 31 ; CHECK-NEXT: [[CONV:%.*]] = zext i32 %r to i64 32 ; CHECK-NEXT: [[AND:%.*]] = and i64 %m, 0 33 ; CHECK-NEXT: [[NEG:%.*]] = xor i64 0, 34359738367 34 ; CHECK-NEXT: [[OR:%.*]] = or i64 %j, 0 35 ; CHECK-NEXT: [[SHL:%.*]] = shl i64 0, 29 36 ; CHECK-NEXT: [[CONV1:%.*]] = select i1 %b, i64 7, i64 0 37 ; CHECK-NEXT: [[SUB:%.*]] = sub i64 [[SHL]], [[CONV1]] 38 ; CHECK-NEXT: [[CONV2:%.*]] = zext i32 %k to i64 39 ; CHECK-NEXT: [[MUL:%.*]] = mul i64 [[SUB]], [[CONV2]] 40 ; CHECK-NEXT: [[CONV4:%.*]] = and i64 %p, 65535 41 ; CHECK-NEXT: [[AND5:%.*]] = and i64 [[MUL]], [[CONV4]] 42 ; CHECK-NEXT: ret i64 [[AND5]] 43 ; 44 %conv = zext i32 %r to i64 45 %and = and i64 %m, %conv 46 %neg = xor i64 %and, 34359738367 47 %or = or i64 %j, %neg 48 %shl = shl i64 %or, 29 49 %conv1 = select i1 %b, i64 7, i64 0 50 %sub = sub nuw nsw i64 %shl, %conv1 51 %conv2 = zext i32 %k to i64 52 %mul = mul nsw i64 %sub, %conv2 53 %conv4 = and i64 %p, 65535 54 %and5 = and i64 %mul, %conv4 55 ret i64 %and5 56 } 57 58 ; This is a manufactured example based on the 1st test to prove that the 59 ; assumption-killing algorithm stops at the call. Ie, it does not remove 60 ; nsw/nuw from the 'add' because a call demands all bits of its argument. 61 62 declare i1 @foo(i1) 63 64 define i1 @poison_on_call_user_is_ok(i1 %b, i8 %x) { 65 ; CHECK-LABEL: @poison_on_call_user_is_ok( 66 ; CHECK-NEXT: [[SETBIT:%.*]] = or i8 %x, 64 67 ; CHECK-NEXT: [[LITTLE_NUMBER:%.*]] = zext i1 %b to i8 68 ; CHECK-NEXT: [[BIG_NUMBER:%.*]] = shl i8 0, 1 69 ; CHECK-NEXT: [[SUB:%.*]] = sub i8 [[BIG_NUMBER]], [[LITTLE_NUMBER]] 70 ; CHECK-NEXT: [[TRUNC:%.*]] = trunc i8 [[SUB]] to i1 71 ; CHECK-NEXT: [[CALL_RESULT:%.*]] = call i1 @foo(i1 [[TRUNC]]) 72 ; CHECK-NEXT: [[ADD:%.*]] = add nuw nsw i1 [[CALL_RESULT]], true 73 ; CHECK-NEXT: [[MUL:%.*]] = mul i1 [[TRUNC]], [[ADD]] 74 ; CHECK-NEXT: ret i1 [[MUL]] 75 ; 76 %setbit = or i8 %x, 64 77 %little_number = zext i1 %b to i8 78 %big_number = shl i8 %setbit, 1 79 %sub = sub nuw i8 %big_number, %little_number 80 %trunc = trunc i8 %sub to i1 81 %call_result = call i1 @foo(i1 %trunc) 82 %add = add nsw nuw i1 %call_result, 1 83 %mul = mul i1 %trunc, %add 84 ret i1 %mul 85 } 86 87 88 ; We were asserting that all users of a trivialized integer-type instruction were 89 ; also integer-typed, but that's too strong. The alloca has a pointer-type result. 90 91 define void @PR34179(i32* %a) { 92 ; CHECK-LABEL: @PR34179( 93 ; CHECK-NEXT: [[T0:%.*]] = load volatile i32, i32* %a 94 ; CHECK-NEXT: ret void 95 ; 96 %t0 = load volatile i32, i32* %a 97 %vla = alloca i32, i32 %t0 98 ret void 99 } 100 101
