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[AArch64][SME2] Add ZT0 attributes to SMEAttrs (llvm#77607)
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This patch extends SMEAttrs to interpret the following new attributes,
which are mutually exclusive and apply to SME2 only:
  - aarch64_sme_zt0_in (ZT0_In)
  - aarch64_sme_zt0_out (ZT0_Out)
  - aarch64_sme_zt0_inout (ZT0_InOut)
  - aarch64_sme_zt0_new (ZT0_New)
  - aarch64_sme_zt0_preserved (ZT0_Preserved)

ZT0_In, ZT0_Out, ZT0_InOut & ZT0_Preserved are all considered to share
ZT0. These attributes will be required by later patches to determine
if ZT0 should be preserved around function calls, or cleared on entry
to the function.
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@kmclaughlin-arm
kmclaughlin-arm committed Jan 16, 2024
1 parent f1f1875 commit a4ec04e
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Showing 5 changed files with 190 additions and 7 deletions.
9 changes: 9 additions & 0 deletions llvm/lib/IR/Verifier.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2161,6 +2161,15 @@ void Verifier::verifyFunctionAttrs(FunctionType *FT, AttributeList Attrs,
V);
}

Check(
(Attrs.hasFnAttr("aarch64_new_zt0") + Attrs.hasFnAttr("aarch64_in_zt0") +
Attrs.hasFnAttr("aarch64_inout_zt0") +
Attrs.hasFnAttr("aarch64_out_zt0") +
Attrs.hasFnAttr("aarch64_preserves_zt0")) <= 1,
"Attributes 'aarch64_new_zt0', 'aarch64_in_zt0', 'aarch64_out_zt0', "
"'aarch64_inout_zt0' and 'aarch64_preserves_zt0' are mutually exclusive",
V);

if (Attrs.hasFnAttr(Attribute::JumpTable)) {
const GlobalValue *GV = cast<GlobalValue>(V);
Check(GV->hasGlobalUnnamedAddr(),
Expand Down
24 changes: 22 additions & 2 deletions llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -18,16 +18,26 @@ void SMEAttrs::set(unsigned M, bool Enable) {
else
Bitmask &= ~M;

// Streaming Mode Attrs
assert(!(hasStreamingInterface() && hasStreamingCompatibleInterface()) &&
"SM_Enabled and SM_Compatible are mutually exclusive");
assert(!(hasNewZABody() && hasSharedZAInterface()) &&

// ZA Attrs
assert(!(hasNewZABody() && sharesZA()) &&
"ZA_New and ZA_Shared are mutually exclusive");
assert(!(hasNewZABody() && preservesZA()) &&
"ZA_New and ZA_Preserved are mutually exclusive");
assert(!(hasNewZABody() && (Bitmask & ZA_NoLazySave)) &&
"ZA_New and ZA_NoLazySave are mutually exclusive");
assert(!(hasSharedZAInterface() && (Bitmask & ZA_NoLazySave)) &&
assert(!(sharesZA() && (Bitmask & ZA_NoLazySave)) &&
"ZA_Shared and ZA_NoLazySave are mutually exclusive");

// ZT0 Attrs
assert(
(!sharesZT0() || (isNewZT0() ^ isInZT0() ^ isInOutZT0() ^ isOutZT0() ^
isPreservesZT0())) &&
"Attributes 'aarch64_new_zt0', 'aarch64_in_zt0', 'aarch64_out_zt0', "
"'aarch64_inout_zt0' and 'aarch64_preserves_zt0' are mutually exclusive");
}

SMEAttrs::SMEAttrs(const CallBase &CB) {
Expand Down Expand Up @@ -60,6 +70,16 @@ SMEAttrs::SMEAttrs(const AttributeList &Attrs) {
Bitmask |= ZA_New;
if (Attrs.hasFnAttr("aarch64_pstate_za_preserved"))
Bitmask |= ZA_Preserved;
if (Attrs.hasFnAttr("aarch64_in_zt0"))
Bitmask |= encodeZT0State(StateValue::In);
if (Attrs.hasFnAttr("aarch64_out_zt0"))
Bitmask |= encodeZT0State(StateValue::Out);
if (Attrs.hasFnAttr("aarch64_inout_zt0"))
Bitmask |= encodeZT0State(StateValue::InOut);
if (Attrs.hasFnAttr("aarch64_preserves_zt0"))
Bitmask |= encodeZT0State(StateValue::Preserved);
if (Attrs.hasFnAttr("aarch64_new_zt0"))
Bitmask |= encodeZT0State(StateValue::New);
}

std::optional<bool>
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43 changes: 38 additions & 5 deletions llvm/lib/Target/AArch64/Utils/AArch64SMEAttributes.h
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,15 @@ class SMEAttrs {
unsigned Bitmask;

public:
enum class StateValue {
None = 0,
In = 1, // aarch64_in_zt0
Out = 2, // aarch64_out_zt0
InOut = 3, // aarch64_inout_zt0
Preserved = 4, // aarch64_preserves_zt0
New = 5 // aarch64_new_zt0
};

// Enum with bitmasks for each individual SME feature.
enum Mask {
Normal = 0,
Expand All @@ -36,7 +45,8 @@ class SMEAttrs {
ZA_New = 1 << 4, // aarch64_pstate_sm_new
ZA_Preserved = 1 << 5, // aarch64_pstate_sm_preserved
ZA_NoLazySave = 1 << 6, // Used for SME ABI routines to avoid lazy saves
All = ZA_Preserved - 1
ZT0_Shift = 7,
ZT0_Mask = 0b111 << ZT0_Shift
};

SMEAttrs(unsigned Mask = Normal) : Bitmask(0) { set(Mask); }
Expand Down Expand Up @@ -76,16 +86,39 @@ class SMEAttrs {

// Interfaces to query PSTATE.ZA
bool hasNewZABody() const { return Bitmask & ZA_New; }
bool hasSharedZAInterface() const { return Bitmask & ZA_Shared; }
bool sharesZA() const { return Bitmask & ZA_Shared; }
bool hasSharedZAInterface() const { return sharesZA() || sharesZT0(); }
bool hasPrivateZAInterface() const { return !hasSharedZAInterface(); }
bool preservesZA() const { return Bitmask & ZA_Preserved; }
bool hasZAState() const {
return hasNewZABody() || hasSharedZAInterface();
}
bool hasZAState() const { return hasNewZABody() || sharesZA(); }
bool requiresLazySave(const SMEAttrs &Callee) const {
return hasZAState() && Callee.hasPrivateZAInterface() &&
!(Callee.Bitmask & ZA_NoLazySave);
}

// Interfaces to query ZT0 State
static StateValue decodeZT0State(unsigned Bitmask) {
return static_cast<StateValue>((Bitmask & ZT0_Mask) >> ZT0_Shift);
}
static unsigned encodeZT0State(StateValue S) {
return static_cast<unsigned>(S) << ZT0_Shift;
}

bool isNewZT0() const { return decodeZT0State(Bitmask) == StateValue::New; }
bool isInZT0() const { return decodeZT0State(Bitmask) == StateValue::In; }
bool isOutZT0() const { return decodeZT0State(Bitmask) == StateValue::Out; }
bool isInOutZT0() const {
return decodeZT0State(Bitmask) == StateValue::InOut;
}
bool isPreservesZT0() const {
return decodeZT0State(Bitmask) == StateValue::Preserved;
}
bool sharesZT0() const {
StateValue State = decodeZT0State(Bitmask);
return State == StateValue::In || State == StateValue::Out ||
State == StateValue::InOut || State == StateValue::Preserved;
}
bool hasZT0State() const { return isNewZT0() || sharesZT0(); }
};

} // namespace llvm
Expand Down
30 changes: 30 additions & 0 deletions llvm/test/Verifier/sme-attributes.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -8,3 +8,33 @@ declare void @za_preserved() "aarch64_pstate_za_new" "aarch64_pstate_za_preserve

declare void @za_shared() "aarch64_pstate_za_new" "aarch64_pstate_za_shared";
; CHECK: Attributes 'aarch64_pstate_za_new and aarch64_pstate_za_shared' are incompatible!

declare void @zt0_new_preserved() "aarch64_new_zt0" "aarch64_preserves_zt0";
; CHECK: Attributes 'aarch64_new_zt0', 'aarch64_in_zt0', 'aarch64_out_zt0', 'aarch64_inout_zt0' and 'aarch64_preserves_zt0' are mutually exclusive

declare void @zt0_new_in() "aarch64_new_zt0" "aarch64_in_zt0";
; CHECK: Attributes 'aarch64_new_zt0', 'aarch64_in_zt0', 'aarch64_out_zt0', 'aarch64_inout_zt0' and 'aarch64_preserves_zt0' are mutually exclusive

declare void @zt0_new_inout() "aarch64_new_zt0" "aarch64_inout_zt0";
; CHECK: Attributes 'aarch64_new_zt0', 'aarch64_in_zt0', 'aarch64_out_zt0', 'aarch64_inout_zt0' and 'aarch64_preserves_zt0' are mutually exclusive

declare void @zt0_new_out() "aarch64_new_zt0" "aarch64_out_zt0";
; CHECK: Attributes 'aarch64_new_zt0', 'aarch64_in_zt0', 'aarch64_out_zt0', 'aarch64_inout_zt0' and 'aarch64_preserves_zt0' are mutually exclusive

declare void @zt0_preserved_in() "aarch64_preserves_zt0" "aarch64_in_zt0";
; CHECK: Attributes 'aarch64_new_zt0', 'aarch64_in_zt0', 'aarch64_out_zt0', 'aarch64_inout_zt0' and 'aarch64_preserves_zt0' are mutually exclusive

declare void @zt0_preserved_inout() "aarch64_preserves_zt0" "aarch64_inout_zt0";
; CHECK: Attributes 'aarch64_new_zt0', 'aarch64_in_zt0', 'aarch64_out_zt0', 'aarch64_inout_zt0' and 'aarch64_preserves_zt0' are mutually exclusive

declare void @zt0_preserved_out() "aarch64_preserves_zt0" "aarch64_out_zt0";
; CHECK: Attributes 'aarch64_new_zt0', 'aarch64_in_zt0', 'aarch64_out_zt0', 'aarch64_inout_zt0' and 'aarch64_preserves_zt0' are mutually exclusive

declare void @zt0_in_inout() "aarch64_in_zt0" "aarch64_inout_zt0";
; CHECK: Attributes 'aarch64_new_zt0', 'aarch64_in_zt0', 'aarch64_out_zt0', 'aarch64_inout_zt0' and 'aarch64_preserves_zt0' are mutually exclusive

declare void @zt0_in_out() "aarch64_in_zt0" "aarch64_out_zt0";
; CHECK: Attributes 'aarch64_new_zt0', 'aarch64_in_zt0', 'aarch64_out_zt0', 'aarch64_inout_zt0' and 'aarch64_preserves_zt0' are mutually exclusive

declare void @zt0_inout_out() "aarch64_inout_zt0" "aarch64_out_zt0";
; CHECK: Attributes 'aarch64_new_zt0', 'aarch64_in_zt0', 'aarch64_out_zt0', 'aarch64_inout_zt0' and 'aarch64_preserves_zt0' are mutually exclusive
91 changes: 91 additions & 0 deletions llvm/unittests/Target/AArch64/SMEAttributesTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,10 @@ TEST(SMEAttributes, Constructors) {
->getFunction("foo"))
.hasStreamingCompatibleInterface());

ASSERT_TRUE(SA(*parseIR("declare void @foo() \"aarch64_pstate_za_shared\"")
->getFunction("foo"))
.sharesZA());

ASSERT_TRUE(SA(*parseIR("declare void @foo() \"aarch64_pstate_za_shared\"")
->getFunction("foo"))
.hasSharedZAInterface());
Expand All @@ -50,6 +54,22 @@ TEST(SMEAttributes, Constructors) {
->getFunction("foo"))
.preservesZA());

ASSERT_TRUE(
SA(*parseIR("declare void @foo() \"aarch64_in_zt0\"")->getFunction("foo"))
.isInZT0());
ASSERT_TRUE(SA(*parseIR("declare void @foo() \"aarch64_out_zt0\"")
->getFunction("foo"))
.isOutZT0());
ASSERT_TRUE(SA(*parseIR("declare void @foo() \"aarch64_inout_zt0\"")
->getFunction("foo"))
.isInOutZT0());
ASSERT_TRUE(SA(*parseIR("declare void @foo() \"aarch64_preserves_zt0\"")
->getFunction("foo"))
.isPreservesZT0());
ASSERT_TRUE(SA(*parseIR("declare void @foo() \"aarch64_new_zt0\"")
->getFunction("foo"))
.isNewZT0());

// Invalid combinations.
EXPECT_DEBUG_DEATH(SA(SA::SM_Enabled | SA::SM_Compatible),
"SM_Enabled and SM_Compatible are mutually exclusive");
Expand Down Expand Up @@ -82,19 +102,90 @@ TEST(SMEAttributes, Basics) {
// Test PSTATE.ZA interfaces.
ASSERT_FALSE(SA(SA::ZA_Shared).hasPrivateZAInterface());
ASSERT_TRUE(SA(SA::ZA_Shared).hasSharedZAInterface());
ASSERT_TRUE(SA(SA::ZA_Shared).sharesZA());
ASSERT_TRUE(SA(SA::ZA_Shared).hasZAState());
ASSERT_FALSE(SA(SA::ZA_Shared).preservesZA());
ASSERT_TRUE(SA(SA::ZA_Shared | SA::ZA_Preserved).preservesZA());
ASSERT_FALSE(SA(SA::ZA_Shared).sharesZT0());
ASSERT_FALSE(SA(SA::ZA_Shared).hasZT0State());

ASSERT_TRUE(SA(SA::ZA_New).hasPrivateZAInterface());
ASSERT_FALSE(SA(SA::ZA_New).hasSharedZAInterface());
ASSERT_TRUE(SA(SA::ZA_New).hasNewZABody());
ASSERT_TRUE(SA(SA::ZA_New).hasZAState());
ASSERT_FALSE(SA(SA::ZA_New).preservesZA());
ASSERT_FALSE(SA(SA::ZA_New).sharesZT0());
ASSERT_FALSE(SA(SA::ZA_New).hasZT0State());

ASSERT_TRUE(SA(SA::Normal).hasPrivateZAInterface());
ASSERT_FALSE(SA(SA::Normal).hasSharedZAInterface());
ASSERT_FALSE(SA(SA::Normal).hasNewZABody());
ASSERT_FALSE(SA(SA::Normal).hasZAState());
ASSERT_FALSE(SA(SA::Normal).preservesZA());

// Test ZT0 State interfaces
SA ZT0_In = SA(SA::encodeZT0State(SA::StateValue::In));
ASSERT_TRUE(ZT0_In.isInZT0());
ASSERT_FALSE(ZT0_In.isOutZT0());
ASSERT_FALSE(ZT0_In.isInOutZT0());
ASSERT_FALSE(ZT0_In.isPreservesZT0());
ASSERT_FALSE(ZT0_In.isNewZT0());
ASSERT_TRUE(ZT0_In.sharesZT0());
ASSERT_TRUE(ZT0_In.hasZT0State());
ASSERT_TRUE(ZT0_In.hasSharedZAInterface());
ASSERT_FALSE(ZT0_In.hasPrivateZAInterface());

SA ZT0_Out = SA(SA::encodeZT0State(SA::StateValue::Out));
ASSERT_TRUE(ZT0_Out.isOutZT0());
ASSERT_FALSE(ZT0_Out.isInZT0());
ASSERT_FALSE(ZT0_Out.isInOutZT0());
ASSERT_FALSE(ZT0_Out.isPreservesZT0());
ASSERT_FALSE(ZT0_Out.isNewZT0());
ASSERT_TRUE(ZT0_Out.sharesZT0());
ASSERT_TRUE(ZT0_Out.hasZT0State());
ASSERT_TRUE(ZT0_Out.hasSharedZAInterface());
ASSERT_FALSE(ZT0_Out.hasPrivateZAInterface());

SA ZT0_InOut = SA(SA::encodeZT0State(SA::StateValue::InOut));
ASSERT_TRUE(ZT0_InOut.isInOutZT0());
ASSERT_FALSE(ZT0_InOut.isInZT0());
ASSERT_FALSE(ZT0_InOut.isOutZT0());
ASSERT_FALSE(ZT0_InOut.isPreservesZT0());
ASSERT_FALSE(ZT0_InOut.isNewZT0());
ASSERT_TRUE(ZT0_InOut.sharesZT0());
ASSERT_TRUE(ZT0_InOut.hasZT0State());
ASSERT_TRUE(ZT0_InOut.hasSharedZAInterface());
ASSERT_FALSE(ZT0_InOut.hasPrivateZAInterface());

SA ZT0_Preserved = SA(SA::encodeZT0State(SA::StateValue::Preserved));
ASSERT_TRUE(ZT0_Preserved.isPreservesZT0());
ASSERT_FALSE(ZT0_Preserved.isInZT0());
ASSERT_FALSE(ZT0_Preserved.isOutZT0());
ASSERT_FALSE(ZT0_Preserved.isInOutZT0());
ASSERT_FALSE(ZT0_Preserved.isNewZT0());
ASSERT_TRUE(ZT0_Preserved.sharesZT0());
ASSERT_TRUE(ZT0_Preserved.hasZT0State());
ASSERT_TRUE(ZT0_Preserved.hasSharedZAInterface());
ASSERT_FALSE(ZT0_Preserved.hasPrivateZAInterface());

SA ZT0_New = SA(SA::encodeZT0State(SA::StateValue::New));
ASSERT_TRUE(ZT0_New.isNewZT0());
ASSERT_FALSE(ZT0_New.isInZT0());
ASSERT_FALSE(ZT0_New.isOutZT0());
ASSERT_FALSE(ZT0_New.isInOutZT0());
ASSERT_FALSE(ZT0_New.isPreservesZT0());
ASSERT_FALSE(ZT0_New.sharesZT0());
ASSERT_TRUE(ZT0_New.hasZT0State());
ASSERT_FALSE(ZT0_New.hasSharedZAInterface());
ASSERT_TRUE(ZT0_New.hasPrivateZAInterface());

ASSERT_FALSE(SA(SA::Normal).isInZT0());
ASSERT_FALSE(SA(SA::Normal).isOutZT0());
ASSERT_FALSE(SA(SA::Normal).isInOutZT0());
ASSERT_FALSE(SA(SA::Normal).isPreservesZT0());
ASSERT_FALSE(SA(SA::Normal).isNewZT0());
ASSERT_FALSE(SA(SA::Normal).sharesZT0());
ASSERT_FALSE(SA(SA::Normal).hasZT0State());
}

TEST(SMEAttributes, Transitions) {
Expand Down

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