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the subtract allows us to deduce that %setbit is not demanded. 5; But if we change that value to '0', then the 'nuw' is no longer valid.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