KnownZero = APInt::getLowBitsSet(BitWidth,
std::min(KnownZero2.countTrailingOnes(),
KnownZero3.countTrailingOnes()));
-
- // If the operation is an addition that can't have signed overflow,
- // then the sign bit is known to be zero if both input sign bits
- // are zero. Similar for two negative inputs.
- if (Opcode == Instruction::Add &&
- cast<OverflowingBinaryOperator>(LU)->hasNoSignedWrap()) {
- if (KnownZero2.isNegative() && KnownZero3.isNegative())
- KnownZero.setBit(BitWidth-1);
- if (KnownOne2.isNegative() && KnownOne3.isNegative())
- KnownOne.setBit(BitWidth-1);
- }
-
break;
}
}
%cmp1 = icmp ne i32 %a.0, 0
ret i1 %cmp1
}
-
-
-; This test makes sure we can determine that the inputs to the sdiv in the loop
-; are non-negative and can become a udiv. This requires that we recognize that
-; the loop induction can never have its sign bit set.
-;
-; CHECK-LABEL: @phi_nsw_induction_sdiv_udiv
-; CHECK: udiv
-; CHECK: udiv
-define i32 @phi_nsw_induction_sdiv_udiv(i32 %NumElts, i32 %ScalarSize) {
-entry:
- %div = udiv i32 128, %ScalarSize
- br label %for.cond
-
-for.cond: ; preds = %for.inc, %entry
- %Sum.0 = phi i32 [ 0, %entry ], [ %add, %for.inc ]
- %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
- %cmp = icmp ne i32 %i.0, %NumElts
- br i1 %cmp, label %for.body, label %for.end
-
-for.body: ; preds = %for.cond
- ; this should become a udiv
- %div1 = sdiv i32 %i.0, %div
- %add = add nsw i32 %Sum.0, %div1
- br label %for.inc
-
-for.inc: ; preds = %for.body
- %inc = add nsw i32 %i.0, 1
- br label %for.cond
-
-for.end: ; preds = %for.cond
- ret i32 %Sum.0
-}
-
-
-; CHECK-LABEL: test_positive_nsw_recurrence
-; CHECK-NOT: bar
-; CHECK: foo
-; CHECK-NOT: bar
-; CHECK: ret
-define void @test_positive_nsw_recurrence(i32 %N) {
-entry:
- br label %for.cond
-
-for.cond: ; preds = %for.inc, %entry
- %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
- %cmp = icmp ne i32 %i.0, %N
- br i1 %cmp, label %for.body, label %for.end
-
-for.body: ; preds = %for.cond
- %and = and i32 %i.0, -2147483648
- %tobool = icmp ne i32 %and, 0
- br i1 %tobool, label %if.then, label %if.else
-
-if.then: ; preds = %for.body
- ; this call should be deleted as %i.0 can never be negative due to no signed wrap
- call void @bar()
- br label %if.end
-
-if.else: ; preds = %for.body
- call void @foo()
- br label %if.end
-
-if.end: ; preds = %if.else, %if.then
- br label %for.inc
-
-for.inc: ; preds = %if.end
- %inc = add nsw i32 %i.0, 1
- br label %for.cond
-
-for.end: ; preds = %for.cond
- ret void
-}
-
-; CHECK-LABEL: test_negative_nsw_recurrence
-; CHECK-NOT: foo
-; CHECK: bar
-; CHECK-NOT: foo
-; CHECK: ret
-define void @test_negative_nsw_recurrence(i32 %N) {
-entry:
- br label %for.cond
-
-for.cond: ; preds = %for.inc, %entry
- %i.0 = phi i32 [ -1, %entry ], [ %inc, %for.inc ]
- %cmp = icmp ne i32 %i.0, %N
- br i1 %cmp, label %for.body, label %for.end
-
-for.body: ; preds = %for.cond
- %and = and i32 %i.0, -2147483648
- %tobool = icmp ne i32 %and, 0
- br i1 %tobool, label %if.then, label %if.else
-
-if.then: ; preds = %for.body
- call void @bar()
- br label %if.end
-
-if.else: ; preds = %for.body
- ; this call should be deleted as %i.0 can never be positive due to no signed wrap
- call void @foo()
- br label %if.end
-
-if.end: ; preds = %if.else, %if.then
- br label %for.inc
-
-for.inc: ; preds = %if.end
- %inc = add nsw i32 %i.0, -1
- br label %for.cond
-
-for.end: ; preds = %for.cond
- ret void
-}
-
-declare void @bar()
-declare void @foo()