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[SimplifyCFG][Attributes] Preserve some non-equal attrs when intersecting #111014

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[SimplifyCFG][Attributes] Preserve some non-equal attrs when intersecting #111014

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c49ab27
[SimplifyCFG] Add tests for preserving some not exactly equal attrs; NFC
goldsteinn Oct 3, 2024
1f62806
[SimplifyCFG][Attributes] Preserve some non-equal attrs when intersec…
goldsteinn Oct 3, 2024
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55 changes: 50 additions & 5 deletions llvm/lib/IR/Attributes.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -973,20 +973,28 @@ AttributeSet::intersectWith(LLVMContext &C, AttributeSet Other) const {
// Loop through all attributes in both this and Other in sorted order. If
// the attribute is only present in one of the sets, it will be set in
// Attr0. If it is present in both sets both Attr0 and Attr1 will be set.
// If the attr is only present in one of the sets, WithoutCur will point to
// the set that doesn't contain Attr0.
Attribute Attr0, Attr1;
if (ItBegin1 == ItEnd1)
const AttributeSet *WithoutCur = nullptr;
if (ItBegin1 == ItEnd1) {
WithoutCur = &Other;
Attr0 = *ItBegin0++;
else if (ItBegin0 == ItEnd0)
} else if (ItBegin0 == ItEnd0) {
WithoutCur = this;
Attr0 = *ItBegin1++;
else {
} else {
int Cmp = ItBegin0->cmpKind(*ItBegin1);
if (Cmp == 0) {
Attr0 = *ItBegin0++;
Attr1 = *ItBegin1++;
} else if (Cmp < 0)
} else if (Cmp < 0) {
WithoutCur = &Other;
Attr0 = *ItBegin0++;
else
} else {
WithoutCur = this;
Attr0 = *ItBegin1++;
}
}
assert(Attr0.isValid() && "Iteration should always yield a valid attr");

Expand All @@ -1011,14 +1019,51 @@ AttributeSet::intersectWith(LLVMContext &C, AttributeSet Other) const {
// If we don't have both attributes, then fail if the attribute is
// must-preserve or drop it otherwise.
if (!Attr1.isValid()) {
assert(WithoutCur != nullptr &&
"Iteration with only one valid attr didn't set WithoutCur");
if (Attribute::intersectMustPreserve(Kind))
return std::nullopt;

// We can preserve some attributes without it being present in both this
// and Other. For example the intersection between ReadOnly and ReadNone
// is ReadOnly.
// NB: MemoryEffects don't need this extra logic. The `&` operator already
// does this type of intersection and missing memory effects implies
// unknown which we can't union.
switch (Kind) {
// ReadOnly + ReadNone -> ReadOnly
case Attribute::ReadOnly:
if (WithoutCur->hasAttribute(Attribute::ReadNone))
Intersected.addAttribute(Attr0);
break;
// ReadNone + ReadOnly -> ReadNone
case Attribute::ReadNone:
if (WithoutCur->hasAttribute(Attribute::ReadOnly))
Intersected.addAttribute(Attribute::ReadOnly);
break;
// Dereferenceable + DereferenceableOrNull -> DereferenceableOrNull
case Attribute::DereferenceableOrNull:
case Attribute::Dereferenceable: {
Attribute::AttrKind OtherKind = Kind == Attribute::Dereferenceable
? Attribute::DereferenceableOrNull
: Attribute::Dereferenceable;
Attr1 = WithoutCur->getAttribute(OtherKind);
if (Attr1.isValid()) {
uint64_t NewVal =
std::min(Attr0.getValueAsInt(), Attr1.getValueAsInt());
Intersected.addRawIntAttr(Attribute::DereferenceableOrNull, NewVal);
}
} break;
default:
break;
}
continue;
}

// We have both attributes so apply the intersection rule.
assert(Attr1.hasKindAsEnum() && Kind == Attr1.getKindAsEnum() &&
"Iterator picked up two different attributes in the same iteration");
assert(WithoutCur == nullptr && "Iteration two valid attrs set WithoutCur");

// Attribute we can intersect with "and"
if (Attribute::intersectWithAnd(Kind)) {
Expand Down
27 changes: 25 additions & 2 deletions llvm/test/Transforms/SimplifyCFG/hoist-cb-diff-attrs.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ else:
define ptr @test_hoist_int_attrs2(i1 %c, ptr %p, i64 %x) {
; CHECK-LABEL: define {{[^@]+}}@test_hoist_int_attrs2
; CHECK-SAME: (i1 [[C:%.*]], ptr [[P:%.*]], i64 [[X:%.*]]) {
; CHECK-NEXT: [[R:%.*]] = call ptr @foo(ptr dereferenceable(50) [[P]], i64 range(i64 10, 1000) [[X]]) #[[ATTR1:[0-9]+]]
; CHECK-NEXT: [[R:%.*]] = call ptr @foo(ptr dereferenceable(50) dereferenceable_or_null(50) [[P]], i64 range(i64 10, 1000) [[X]]) #[[ATTR1:[0-9]+]]
; CHECK-NEXT: br i1 [[C]], label [[COMMON_RET:%.*]], label [[ELSE:%.*]]
; CHECK: common.ret:
; CHECK-NEXT: ret ptr [[R]]
Expand All @@ -49,10 +49,33 @@ else:
ret ptr %r2
}

define ptr @test_hoist_int_attrs3(i1 %c, ptr %p, ptr %p2, i64 %x) {
; CHECK-LABEL: define {{[^@]+}}@test_hoist_int_attrs3
; CHECK-SAME: (i1 [[C:%.*]], ptr [[P:%.*]], ptr [[P2:%.*]], i64 [[X:%.*]]) {
; CHECK-NEXT: [[R:%.*]] = call ptr @foo2(ptr align 32 dereferenceable_or_null(100) [[P]], ptr align 32 dereferenceable_or_null(100) [[P2]], i64 range(i64 10, 100000) [[X]]) #[[ATTR0]]
; CHECK-NEXT: br i1 [[C]], label [[COMMON_RET:%.*]], label [[ELSE:%.*]]
; CHECK: common.ret:
; CHECK-NEXT: ret ptr [[R]]
; CHECK: else:
; CHECK-NEXT: call void @side.effect()
; CHECK-NEXT: br label [[COMMON_RET]]
;
br i1 %c, label %if, label %else
if:
%r = call ptr @foo2(ptr align 64 dereferenceable(100) %p, ptr dereferenceable(500) align 64 %p2, i64 range(i64 10, 1000) %x) memory(read)
ret ptr %r

else:
%r2 = call ptr @foo2(ptr align 32 dereferenceable_or_null(200) %p, ptr dereferenceable_or_null(100) align 32 %p2, i64 range(i64 10000, 100000) %x) memory(write)
call void @side.effect()
ret ptr %r2
}


define ptr @test_hoist_bool_attrs2(i1 %c, ptr %p, i64 %x) {
; CHECK-LABEL: define {{[^@]+}}@test_hoist_bool_attrs2
; CHECK-SAME: (i1 [[C:%.*]], ptr [[P:%.*]], i64 [[X:%.*]]) {
; CHECK-NEXT: [[R:%.*]] = call noundef ptr @foo(ptr nonnull [[P]], i64 noundef [[X]]) #[[ATTR2:[0-9]+]]
; CHECK-NEXT: [[R:%.*]] = call noundef ptr @foo(ptr nonnull readonly [[P]], i64 noundef [[X]]) #[[ATTR2:[0-9]+]]
; CHECK-NEXT: br i1 [[C]], label [[COMMON_RET:%.*]], label [[ELSE:%.*]]
; CHECK: common.ret:
; CHECK-NEXT: ret ptr [[R]]
Expand Down
29 changes: 27 additions & 2 deletions llvm/test/Transforms/SimplifyCFG/sink-cb-diff-attrs.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,7 @@ define ptr @test_sink_int_attrs2(i1 %c, ptr %p, i64 %x) {
; CHECK-NEXT: call void @side.effect()
; CHECK-NEXT: br label [[END]]
; CHECK: end:
; CHECK-NEXT: [[R2:%.*]] = call ptr @foo(ptr dereferenceable(50) [[P]], i64 range(i64 10, 1000) [[X]]) #[[ATTR2:[0-9]+]]
; CHECK-NEXT: [[R2:%.*]] = call ptr @foo(ptr dereferenceable(50) dereferenceable_or_null(50) [[P]], i64 range(i64 10, 1000) [[X]]) #[[ATTR2:[0-9]+]]
; CHECK-NEXT: ret ptr [[R2]]
;
br i1 %c, label %if, label %else
Expand All @@ -110,6 +110,31 @@ end:
ret ptr %pr
}

define ptr @test_sink_int_attrs3(i1 %c, ptr %p, i64 %x) {
; CHECK-LABEL: define {{[^@]+}}@test_sink_int_attrs3
; CHECK-SAME: (i1 [[C:%.*]], ptr [[P:%.*]], i64 [[X:%.*]]) {
; CHECK-NEXT: br i1 [[C]], label [[IF:%.*]], label [[END:%.*]]
; CHECK: if:
; CHECK-NEXT: call void @side.effect()
; CHECK-NEXT: br label [[END]]
; CHECK: end:
; CHECK-NEXT: [[R2:%.*]] = call ptr @foo(ptr dereferenceable_or_null(50) [[P]], i64 range(i64 10, 1000) [[X]]) #[[ATTR2]]
; CHECK-NEXT: ret ptr [[R2]]
;
br i1 %c, label %if, label %else
if:
call void @side.effect()
%r = call ptr @foo(ptr dereferenceable_or_null(50) %p, i64 range(i64 10, 1000) %x) memory(read)
br label %end

else:
%r2 = call ptr @foo(ptr dereferenceable(100) align 32 %p, i64 range(i64 11, 100) %x) memory(none)
br label %end
end:
%pr = phi ptr [ %r, %if], [%r2, %else]
ret ptr %pr
}

define ptr @test_sink_bool_attrs2(i1 %c, ptr %p, i64 %x) {
; CHECK-LABEL: define {{[^@]+}}@test_sink_bool_attrs2
; CHECK-SAME: (i1 [[C:%.*]], ptr [[P:%.*]], i64 [[X:%.*]]) {
Expand All @@ -118,7 +143,7 @@ define ptr @test_sink_bool_attrs2(i1 %c, ptr %p, i64 %x) {
; CHECK-NEXT: call void @side.effect()
; CHECK-NEXT: br label [[END]]
; CHECK: end:
; CHECK-NEXT: [[R2:%.*]] = call noundef ptr @foo(ptr nonnull [[P]], i64 noundef [[X]]) #[[ATTR3:[0-9]+]]
; CHECK-NEXT: [[R2:%.*]] = call noundef ptr @foo(ptr nonnull readonly [[P]], i64 noundef [[X]]) #[[ATTR3:[0-9]+]]
; CHECK-NEXT: ret ptr [[R2]]
;
br i1 %c, label %if, label %else
Expand Down
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