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llvm-mirror/test/Transforms/BDCE/invalidate-assumptions.ll
Sanjay Patel c34d06472c [BDCE] reduce scope of an assert (PR34179)
The assert was added with r310779 and is usually correct,
but as the test shows, not always. The 'volatile' on the
load is needed to expose the faulty path because without
it, DemandedBits would return that the load is just dead
rather than not demanded, and so we wouldn't hit the
bogus assert.

Also, since the lambda is just a single-line now, get rid 
of it and inline the DB.isAllOnesValue() calls. 

This should fix (prevent execution of a faulty assert):
https://bugs.llvm.org/show_bug.cgi?id=34179

llvm-svn: 310842
2017-08-14 15:13:46 +00:00

101 lines
3.6 KiB
LLVM

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; But if we change that value to '0', then the 'nuw' is no longer valid.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