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8367103: RISC-V: store cpu features in a bitmap #27152

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a3bb913
initial commit
Sep 8, 2025
39deeb8
rename own to current
Sep 8, 2025
0b6fe73
remove RVFeatureValue::_enabled
Sep 8, 2025
9c1df09
split extension and non-extension features
Sep 8, 2025
9c6c32f
refine
Sep 8, 2025
e27247b
initial commit
Sep 12, 2025
4a75e87
Merge branch 'openjdk:master' into master
Hamlin-Li Sep 12, 2025
4ee1df1
Merge branch 'openjdk:master' into master
Hamlin-Li Sep 15, 2025
08bd5dd
merge master
Sep 15, 2025
0ef6842
refine
Sep 15, 2025
6b33210
fix typo
Sep 17, 2025
eac955a
simplify names
Sep 22, 2025
414f146
refine
Sep 24, 2025
8a00f21
remove explicit cpu feature index in RV_EXT_FEATURE_FLAGS
Sep 24, 2025
3131ab7
undef macros
Sep 24, 2025
f19196f
refine
Sep 25, 2025
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29 changes: 21 additions & 8 deletions src/hotspot/cpu/riscv/vm_version_riscv.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -35,15 +35,28 @@

uint32_t VM_Version::_initial_vector_length = 0;

#define DEF_RV_FEATURE(NAME, PRETTY, BIT, FSTRING, FLAGF) \
VM_Version::NAME##RVFeatureValue VM_Version::NAME(PRETTY, BIT, FSTRING);
RV_FEATURE_FLAGS(DEF_RV_FEATURE)

#define ADD_RV_FEATURE_IN_LIST(NAME, PRETTY, BIT, FSTRING, FLAGF) \
&VM_Version::NAME,
VM_Version::RVFeatureValue* VM_Version::_feature_list[] = {
RV_FEATURE_FLAGS(ADD_RV_FEATURE_IN_LIST)
#define DEF_RV_EXT_FEATURE(NAME, PRETTY, LINUX_BIT, FSTRING, FLAGF) \
VM_Version::NAME##RVExtFeatureValue VM_Version::NAME;
RV_EXT_FEATURE_FLAGS(DEF_RV_EXT_FEATURE)
#undef DEF_RV_EXT_FEATURE

#define DEF_RV_NON_EXT_FEATURE(NAME, PRETTY, LINUX_BIT, FSTRING, FLAGF) \
VM_Version::NAME##RVNonExtFeatureValue VM_Version::NAME;
RV_NON_EXT_FEATURE_FLAGS(DEF_RV_NON_EXT_FEATURE)
#undef DEF_RV_NON_EXT_FEATURE

#define ADD_RV_EXT_FEATURE_IN_LIST(NAME, PRETTY, LINUX_BIT, FSTRING, FLAGF) \
&VM_Version::NAME,
#define ADD_RV_NON_EXT_FEATURE_IN_LIST(NAME, PRETTY, LINUX_BIT, FSTRING, FLAGF) \
&VM_Version::NAME,
VM_Version::RVFeatureValue* VM_Version::_feature_list[] = {
RV_EXT_FEATURE_FLAGS(ADD_RV_EXT_FEATURE_IN_LIST)
RV_NON_EXT_FEATURE_FLAGS(ADD_RV_NON_EXT_FEATURE_IN_LIST)
nullptr};
#undef ADD_RV_NON_EXT_FEATURE_IN_LIST
#undef ADD_RV_EXT_FEATURE_IN_LIST

VM_Version::RVExtFeatures* VM_Version::_rv_ext_features = new VM_Version::RVExtFeatures();

void VM_Version::useRVA20U64Profile() {
RV_USE_RVA20U64;
Expand Down
247 changes: 184 additions & 63 deletions src/hotspot/cpu/riscv/vm_version_riscv.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -46,30 +46,29 @@ class VM_Version : public Abstract_VM_Version {
RIVOS = 0x6cf, // JEDEC: 0x4f, Bank: 14
};

class RVExtFeatures;

class RVFeatureValue {
const char* const _pretty;
const bool _feature_string;
const uint64_t _feature_bit;
bool _enabled;
const uint64_t _linux_feature_bit;
int64_t _value;
public:
RVFeatureValue(const char* pretty, int bit_num, bool fstring) :
_pretty(pretty), _feature_string(fstring), _feature_bit(nth_bit(bit_num)),
_enabled(false), _value(-1) {
RVFeatureValue(const char* pretty, int linux_bit_num, bool fstring) :
_pretty(pretty), _feature_string(fstring), _linux_feature_bit(nth_bit(linux_bit_num)),
_value(-1) {
}
void enable_feature(int64_t value = 0) {
_enabled = true;
virtual void enable_feature(int64_t value = 0) {
_value = value;
}
void disable_feature() {
_enabled = false;
virtual void disable_feature() {
_value = -1;
}
const char* pretty() { return _pretty; }
uint64_t feature_bit() { return _feature_bit; }
uint64_t feature_bit() { return _linux_feature_bit; }
bool feature_string() { return _feature_string; }
bool enabled() { return _enabled; }
int64_t value() { return _value; }
virtual bool enabled() = 0;
virtual void update_flag() = 0;
};

Expand Down Expand Up @@ -111,6 +110,45 @@ class VM_Version : public Abstract_VM_Version {
#define NO_UPDATE_DEFAULT \
void update_flag() {} \


class RVExtFeatureValue : public RVFeatureValue {
const uint32_t _cpu_feature_index;
public:
RVExtFeatureValue(const char* pretty, int linux_bit_num, uint32_t cpu_feature_index, bool fstring) :
RVFeatureValue(pretty, linux_bit_num, fstring),
_cpu_feature_index(cpu_feature_index) {
}
bool enabled() {
return RVExtFeatures::current()->support_feature(_cpu_feature_index);
}
void enable_feature(int64_t value = 0) {
RVFeatureValue::enable_feature(value);
RVExtFeatures::current()->set_feature(_cpu_feature_index);
}
void disable_feature() {
RVFeatureValue::disable_feature();
RVExtFeatures::current()->clear_feature(_cpu_feature_index);
}
};

class RVNonExtFeatureValue : public RVFeatureValue {
bool _enabled;
public:
RVNonExtFeatureValue(const char* pretty, int linux_bit_num, bool fstring) :
RVFeatureValue(pretty, linux_bit_num, fstring),
_enabled(false) {
}
bool enabled() { return _enabled; }
void enable_feature(int64_t value = 0) {
RVFeatureValue::enable_feature(value);
_enabled = true;
}
void disable_feature() {
RVFeatureValue::disable_feature();
_enabled = false;
}
};

// Frozen standard extensions
// I RV64I
// M Integer Multiplication and Division
Expand Down Expand Up @@ -161,58 +199,140 @@ class VM_Version : public Abstract_VM_Version {
#define RV_NO_FLAG_BIT (BitsPerWord+1) // nth_bit will return 0 on values larger than BitsPerWord

// Note: the order matters, depender should be after their dependee. E.g. ext_V before ext_Zvbb.
// declaration name , extension name, bit pos ,in str, mapped flag)
#define RV_FEATURE_FLAGS(decl) \
decl(ext_I , "i" , ('I' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_M , "m" , ('M' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_A , "a" , ('A' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_F , "f" , ('F' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_D , "d" , ('D' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_C , "c" , ('C' - 'A'), true , UPDATE_DEFAULT(UseRVC)) \
decl(ext_Q , "q" , ('Q' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_H , "h" , ('H' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_V , "v" , ('V' - 'A'), true , UPDATE_DEFAULT(UseRVV)) \
decl(ext_Zicbom , "Zicbom" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZicbom)) \
decl(ext_Zicboz , "Zicboz" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZicboz)) \
decl(ext_Zicbop , "Zicbop" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZicbop)) \
decl(ext_Zba , "Zba" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZba)) \
decl(ext_Zbb , "Zbb" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZbb)) \
decl(ext_Zbc , "Zbc" , RV_NO_FLAG_BIT, true , NO_UPDATE_DEFAULT) \
decl(ext_Zbs , "Zbs" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZbs)) \
decl(ext_Zbkb , "Zbkb" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZbkb)) \
decl(ext_Zcb , "Zcb" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZcb)) \
decl(ext_Zfa , "Zfa" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZfa)) \
decl(ext_Zfh , "Zfh" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZfh)) \
decl(ext_Zfhmin , "Zfhmin" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZfhmin)) \
decl(ext_Zicsr , "Zicsr" , RV_NO_FLAG_BIT, true , NO_UPDATE_DEFAULT) \
decl(ext_Zicntr , "Zicntr" , RV_NO_FLAG_BIT, true , NO_UPDATE_DEFAULT) \
decl(ext_Zifencei , "Zifencei" , RV_NO_FLAG_BIT, true , NO_UPDATE_DEFAULT) \
decl(ext_Zic64b , "Zic64b" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZic64b)) \
decl(ext_Ztso , "Ztso" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZtso)) \
decl(ext_Zihintpause , "Zihintpause" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZihintpause)) \
decl(ext_Zacas , "Zacas" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZacas)) \
decl(ext_Zvbb , "Zvbb" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT_DEP(UseZvbb, ext_V)) \
decl(ext_Zvbc , "Zvbc" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT_DEP(UseZvbc, ext_V)) \
decl(ext_Zvfh , "Zvfh" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT_DEP(UseZvfh, ext_V)) \
decl(ext_Zvkn , "Zvkn" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT_DEP(UseZvkn, ext_V)) \
decl(ext_Zicond , "Zicond" , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZicond)) \
decl(mvendorid , "VendorId" , RV_NO_FLAG_BIT, false, NO_UPDATE_DEFAULT) \
decl(marchid , "ArchId" , RV_NO_FLAG_BIT, false, NO_UPDATE_DEFAULT) \
decl(mimpid , "ImpId" , RV_NO_FLAG_BIT, false, NO_UPDATE_DEFAULT) \
decl(unaligned_access , "Unaligned" , RV_NO_FLAG_BIT, false, NO_UPDATE_DEFAULT) \
decl(satp_mode , "SATP" , RV_NO_FLAG_BIT, false, NO_UPDATE_DEFAULT) \
decl(zicboz_block_size, "ZicbozBlockSize", RV_NO_FLAG_BIT, false, NO_UPDATE_DEFAULT) \

#define DECLARE_RV_FEATURE(NAME, PRETTY, BIT, FSTRING, FLAGF) \
struct NAME##RVFeatureValue : public RVFeatureValue { \
NAME##RVFeatureValue(const char* pretty, int bit, bool fstring) : \
RVFeatureValue(pretty, bit, fstring) {} \
FLAGF; \
}; \
static NAME##RVFeatureValue NAME; \

RV_FEATURE_FLAGS(DECLARE_RV_FEATURE)
#undef DECLARE_RV_FEATURE
//
// Fields description in `decl`:
// declaration name, extension name, bit value from linux, feature string?, mapped flag)
#define RV_EXT_FEATURE_FLAGS(decl) \
decl(ext_I , i , ('I' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_M , m , ('M' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_A , a , ('A' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_F , f , ('F' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_D , d , ('D' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_C , c , ('C' - 'A'), true , UPDATE_DEFAULT(UseRVC)) \
decl(ext_Q , q , ('Q' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_H , h , ('H' - 'A'), true , NO_UPDATE_DEFAULT) \
decl(ext_V , v , ('V' - 'A'), true , UPDATE_DEFAULT(UseRVV)) \
decl(ext_Zicbom , Zicbom , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZicbom)) \
decl(ext_Zicboz , Zicboz , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZicboz)) \
decl(ext_Zicbop , Zicbop , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZicbop)) \
decl(ext_Zba , Zba , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZba)) \
decl(ext_Zbb , Zbb , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZbb)) \
decl(ext_Zbc , Zbc , RV_NO_FLAG_BIT, true , NO_UPDATE_DEFAULT) \
decl(ext_Zbs , Zbs , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZbs)) \
decl(ext_Zbkb , Zbkb , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZbkb)) \
decl(ext_Zcb , Zcb , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZcb)) \
decl(ext_Zfa , Zfa , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZfa)) \
decl(ext_Zfh , Zfh , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZfh)) \
decl(ext_Zfhmin , Zfhmin , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZfhmin)) \
decl(ext_Zicsr , Zicsr , RV_NO_FLAG_BIT, true , NO_UPDATE_DEFAULT) \
decl(ext_Zicntr , Zicntr , RV_NO_FLAG_BIT, true , NO_UPDATE_DEFAULT) \
decl(ext_Zifencei , Zifencei , RV_NO_FLAG_BIT, true , NO_UPDATE_DEFAULT) \
decl(ext_Zic64b , Zic64b , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZic64b)) \
decl(ext_Ztso , Ztso , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZtso)) \
decl(ext_Zihintpause , Zihintpause , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZihintpause)) \
decl(ext_Zacas , Zacas , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZacas)) \
decl(ext_Zvbb , Zvbb , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT_DEP(UseZvbb, ext_V)) \
decl(ext_Zvbc , Zvbc , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT_DEP(UseZvbc, ext_V)) \
decl(ext_Zvfh , Zvfh , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT_DEP(UseZvfh, ext_V)) \
decl(ext_Zvkn , Zvkn , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT_DEP(UseZvkn, ext_V)) \
decl(ext_Zicond , Zicond , RV_NO_FLAG_BIT, true , UPDATE_DEFAULT(UseZicond)) \

#define DECLARE_RV_EXT_FEATURE(NAME, PRETTY, LINUX_BIT, FSTRING, FLAGF) \
struct NAME##RVExtFeatureValue : public RVExtFeatureValue { \
NAME##RVExtFeatureValue() : \
RVExtFeatureValue(#PRETTY, LINUX_BIT, RVExtFeatures::CPU_##NAME, FSTRING) {} \
FLAGF; \
}; \
static NAME##RVExtFeatureValue NAME; \

RV_EXT_FEATURE_FLAGS(DECLARE_RV_EXT_FEATURE)
#undef DECLARE_RV_EXT_FEATURE

// Non-extension features
//
#define RV_NON_EXT_FEATURE_FLAGS(decl) \
decl(unaligned_access , Unaligned , RV_NO_FLAG_BIT, false, NO_UPDATE_DEFAULT) \
decl(mvendorid , VendorId , RV_NO_FLAG_BIT, false, NO_UPDATE_DEFAULT) \
decl(marchid , ArchId , RV_NO_FLAG_BIT, false, NO_UPDATE_DEFAULT) \
decl(mimpid , ImpId , RV_NO_FLAG_BIT, false, NO_UPDATE_DEFAULT) \
decl(satp_mode , SATP , RV_NO_FLAG_BIT, false, NO_UPDATE_DEFAULT) \
decl(zicboz_block_size, ZicbozBlockSize , RV_NO_FLAG_BIT, false, NO_UPDATE_DEFAULT) \

#define DECLARE_RV_NON_EXT_FEATURE(NAME, PRETTY, LINUX_BIT, FSTRING, FLAGF) \
struct NAME##RVNonExtFeatureValue : public RVNonExtFeatureValue { \
NAME##RVNonExtFeatureValue() : \
RVNonExtFeatureValue(#PRETTY, LINUX_BIT, FSTRING) {} \
FLAGF; \
}; \
static NAME##RVNonExtFeatureValue NAME; \

RV_NON_EXT_FEATURE_FLAGS(DECLARE_RV_NON_EXT_FEATURE)
#undef DECLARE_RV_NON_EXT_FEATURE

private:
// Utility for AOT CPU feature store/check.
class RVExtFeatures : public CHeapObj<mtCode> {
public:
enum RVFeatureIndex {
#define DECLARE_RV_FEATURE_ENUM(NAME, PRETTY, LINUX_BIT, FSTRING, FLAGF) CPU_##NAME,

RV_EXT_FEATURE_FLAGS(DECLARE_RV_FEATURE_ENUM)
MAX_CPU_FEATURE_INDEX
#undef DECLARE_RV_FEATURE_ENUM
};
private:
uint64_t _features_bitmap[(MAX_CPU_FEATURE_INDEX / BitsPerLong) + 1];
STATIC_ASSERT(sizeof(_features_bitmap) * BitsPerByte >= MAX_CPU_FEATURE_INDEX);

// Number of 8-byte elements in _features_bitmap.
constexpr static int element_count() {
return sizeof(_features_bitmap) / sizeof(uint64_t);
}

static int element_index(RVFeatureIndex feature) {
int idx = feature / BitsPerLong;
assert(idx < element_count(), "Features array index out of bounds");
return idx;
}

static uint64_t feature_bit(RVFeatureIndex feature) {
return (1ULL << (feature % BitsPerLong));
}

static RVFeatureIndex convert(uint32_t index) {
assert(index < MAX_CPU_FEATURE_INDEX, "must");
return (RVFeatureIndex)index;
}

public:
static RVExtFeatures* current() {
return _rv_ext_features;
}

RVExtFeatures() {
for (int i = 0; i < element_count(); i++) {
_features_bitmap[i] = 0;
}
}

void set_feature(uint32_t feature) {
RVFeatureIndex f = convert(feature);
int idx = element_index(f);
_features_bitmap[idx] |= feature_bit(f);
}

void clear_feature(uint32_t feature) {
RVFeatureIndex f = convert(feature);
int idx = element_index(f);
_features_bitmap[idx] &= ~feature_bit(f);
}

bool support_feature(uint32_t feature) {
RVFeatureIndex f = convert(feature);
int idx = element_index(f);
return (_features_bitmap[idx] & feature_bit(f)) != 0;
}
};

// enable extensions based on profile, current supported profiles:
// RVA20U64
Expand Down Expand Up @@ -286,6 +406,7 @@ class VM_Version : public Abstract_VM_Version {

// Null terminated list
static RVFeatureValue* _feature_list[];
static RVExtFeatures* _rv_ext_features;

// Enables features in _feature_list
static void setup_cpu_available_features();
Expand Down