[reland][libc] Make BigInt bit_cast-able to compatible types #74862
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Fix llvm#74258 This is a reland of llvm#74837
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@llvm/pr-subscribers-libc Author: Guillaume Chatelet (gchatelet) ChangesFix #74258 The fix was to explicitly initialize Full diff: https://github.com/llvm/llvm-project/pull/74862.diff 4 Files Affected:
diff --git a/libc/src/__support/UInt.h b/libc/src/__support/UInt.h
index f72b995f8788db..bdc713e6a8db2b 100644
--- a/libc/src/__support/UInt.h
+++ b/libc/src/__support/UInt.h
@@ -25,12 +25,13 @@
namespace LIBC_NAMESPACE::cpp {
+// BigInt has the same semantics as the 'standard integer types' and can be
+// safely 'bit_cast'ed to compatible types.
template <size_t Bits, bool Signed> struct BigInt {
-
static_assert(Bits > 0 && Bits % 64 == 0,
"Number of bits in BigInt should be a multiple of 64.");
LIBC_INLINE_VAR static constexpr size_t WORDCOUNT = Bits / 64;
- uint64_t val[WORDCOUNT]{};
+ uint64_t val[WORDCOUNT];
LIBC_INLINE_VAR static constexpr uint64_t MASK32 = 0xFFFFFFFFu;
@@ -158,7 +159,7 @@ template <size_t Bits, bool Signed> struct BigInt {
LIBC_INLINE constexpr BigInt<Bits, Signed>
operator+(const BigInt<Bits, Signed> &other) const {
- BigInt<Bits, Signed> result;
+ BigInt<Bits, Signed> result(0);
SumCarry<uint64_t> s{0, 0};
for (size_t i = 0; i < WORDCOUNT; ++i) {
s = add_with_carry(val[i], other.val[i], s.carry);
@@ -171,7 +172,7 @@ template <size_t Bits, bool Signed> struct BigInt {
// it will always use the constexpr version of add_with_carry.
LIBC_INLINE constexpr BigInt<Bits, Signed>
operator+(BigInt<Bits, Signed> &&other) const {
- BigInt<Bits, Signed> result;
+ BigInt<Bits, Signed> result(0);
SumCarry<uint64_t> s{0, 0};
for (size_t i = 0; i < WORDCOUNT; ++i) {
s = add_with_carry_const(val[i], other.val[i], s.carry);
@@ -199,7 +200,7 @@ template <size_t Bits, bool Signed> struct BigInt {
LIBC_INLINE BigInt<Bits, Signed>
operator-(const BigInt<Bits, Signed> &other) const {
- BigInt<Bits, Signed> result;
+ BigInt<Bits, Signed> result(0);
DiffBorrow<uint64_t> d{0, 0};
for (size_t i = 0; i < WORDCOUNT; ++i) {
d = sub_with_borrow(val[i], other.val[i], d.borrow);
@@ -210,7 +211,7 @@ template <size_t Bits, bool Signed> struct BigInt {
LIBC_INLINE constexpr BigInt<Bits, Signed>
operator-(BigInt<Bits, Signed> &&other) const {
- BigInt<Bits, Signed> result;
+ BigInt<Bits, Signed> result(0);
DiffBorrow<uint64_t> d{0, 0};
for (size_t i = 0; i < WORDCOUNT; ++i) {
d = sub_with_borrow_const(val[i], other.val[i], d.borrow);
@@ -690,7 +691,7 @@ template <size_t Bits, bool Signed> struct BigInt {
LIBC_INLINE constexpr BigInt<Bits, Signed>
operator&(const BigInt<Bits, Signed> &other) const {
- BigInt<Bits, Signed> result;
+ BigInt<Bits, Signed> result(0);
for (size_t i = 0; i < WORDCOUNT; ++i)
result.val[i] = val[i] & other.val[i];
return result;
@@ -705,7 +706,7 @@ template <size_t Bits, bool Signed> struct BigInt {
LIBC_INLINE constexpr BigInt<Bits, Signed>
operator|(const BigInt<Bits, Signed> &other) const {
- BigInt<Bits, Signed> result;
+ BigInt<Bits, Signed> result(0);
for (size_t i = 0; i < WORDCOUNT; ++i)
result.val[i] = val[i] | other.val[i];
return result;
@@ -720,7 +721,7 @@ template <size_t Bits, bool Signed> struct BigInt {
LIBC_INLINE constexpr BigInt<Bits, Signed>
operator^(const BigInt<Bits, Signed> &other) const {
- BigInt<Bits, Signed> result;
+ BigInt<Bits, Signed> result(0);
for (size_t i = 0; i < WORDCOUNT; ++i)
result.val[i] = val[i] ^ other.val[i];
return result;
@@ -734,7 +735,7 @@ template <size_t Bits, bool Signed> struct BigInt {
}
LIBC_INLINE constexpr BigInt<Bits, Signed> operator~() const {
- BigInt<Bits, Signed> result;
+ BigInt<Bits, Signed> result(0);
for (size_t i = 0; i < WORDCOUNT; ++i)
result.val[i] = ~val[i];
return result;
diff --git a/libc/test/src/__support/CMakeLists.txt b/libc/test/src/__support/CMakeLists.txt
index 740209bc83d75e..187b70781bdad7 100644
--- a/libc/test/src/__support/CMakeLists.txt
+++ b/libc/test/src/__support/CMakeLists.txt
@@ -89,8 +89,11 @@ add_libc_test(
SRCS
uint_test.cpp
DEPENDS
- libc.src.__support.uint
+ libc.src.__support.CPP.bit
libc.src.__support.CPP.optional
+ libc.src.__support.CPP.type_traits
+ libc.src.__support.macros.properties.float
+ libc.src.__support.uint
)
add_libc_test(
diff --git a/libc/test/src/__support/uint_test.cpp b/libc/test/src/__support/uint_test.cpp
index 971bac55bd9d3f..e4d24b08da867c 100644
--- a/libc/test/src/__support/uint_test.cpp
+++ b/libc/test/src/__support/uint_test.cpp
@@ -6,23 +6,73 @@
//
//===----------------------------------------------------------------------===//
+#include "src/__support/CPP/bit.h" // bit_cast
#include "src/__support/CPP/optional.h"
+#include "src/__support/CPP/type_traits.h" // is_trivially_constructible
#include "src/__support/UInt.h"
+#include "src/__support/macros/properties/float.h" // LIBC_COMPILER_HAS_FLOAT128
#include "test/UnitTest/Test.h"
-// We want to test LIBC_NAMESPACE::cpp::UInt<128> explicitly. So, for
+#include <math.h> // HUGE_VALF, HUGE_VALF
+
+namespace LIBC_NAMESPACE {
+
+using LL_UInt64 = cpp::UInt<64>;
+// We want to test cpp::UInt<128> explicitly. So, for
// convenience, we use a sugar which does not conflict with the UInt128 type
// which can resolve to __uint128_t if the platform has it.
-using LL_UInt128 = LIBC_NAMESPACE::cpp::UInt<128>;
-using LL_UInt192 = LIBC_NAMESPACE::cpp::UInt<192>;
-using LL_UInt256 = LIBC_NAMESPACE::cpp::UInt<256>;
-using LL_UInt320 = LIBC_NAMESPACE::cpp::UInt<320>;
-using LL_UInt512 = LIBC_NAMESPACE::cpp::UInt<512>;
-using LL_UInt1024 = LIBC_NAMESPACE::cpp::UInt<1024>;
+using LL_UInt128 = cpp::UInt<128>;
+using LL_UInt192 = cpp::UInt<192>;
+using LL_UInt256 = cpp::UInt<256>;
+using LL_UInt320 = cpp::UInt<320>;
+using LL_UInt512 = cpp::UInt<512>;
+using LL_UInt1024 = cpp::UInt<1024>;
+
+using LL_Int128 = cpp::Int<128>;
+using LL_Int192 = cpp::Int<192>;
+
+TEST(LlvmLibcUIntClassTest, BitCastToFromDouble) {
+ static_assert(cpp::is_trivially_constructible<LL_UInt64>::value);
+ static_assert(cpp::is_trivially_copyable<LL_UInt64>::value);
+ static_assert(sizeof(LL_UInt64) == sizeof(double));
+ const double inf = HUGE_VAL;
+ const double max = DBL_MAX;
+ const double array[] = {0.0, 0.1, 1.0, max, inf};
+ for (double value : array) {
+ LL_UInt64 back = cpp::bit_cast<LL_UInt64>(value);
+ double forth = cpp::bit_cast<double>(back);
+ EXPECT_TRUE(value == forth);
+ }
+}
-using LL_Int128 = LIBC_NAMESPACE::cpp::Int<128>;
-using LL_Int192 = LIBC_NAMESPACE::cpp::Int<192>;
+#ifdef __SIZEOF_INT128__
+TEST(LlvmLibcUIntClassTest, BitCastToFromNativeUint128) {
+ static_assert(cpp::is_trivially_constructible<LL_UInt128>::value);
+ static_assert(cpp::is_trivially_copyable<LL_UInt128>::value);
+ static_assert(sizeof(LL_UInt128) == sizeof(__uint128_t));
+ const __uint128_t array[] = {0, 1, ~__uint128_t(0)};
+ for (__uint128_t value : array) {
+ LL_UInt128 back = cpp::bit_cast<LL_UInt128>(value);
+ __uint128_t forth = cpp::bit_cast<__uint128_t>(back);
+ EXPECT_TRUE(value == forth);
+ }
+}
+#endif
+
+#ifdef LIBC_COMPILER_HAS_FLOAT128
+TEST(LlvmLibcUIntClassTest, BitCastToFromNativeFloat128) {
+ static_assert(cpp::is_trivially_constructible<LL_UInt128>::value);
+ static_assert(cpp::is_trivially_copyable<LL_UInt128>::value);
+ static_assert(sizeof(LL_UInt128) == sizeof(float128));
+ const float128 array[] = {0, 0.1, 1};
+ for (float128 value : array) {
+ LL_UInt128 back = cpp::bit_cast<LL_UInt128>(value);
+ float128 forth = cpp::bit_cast<float128>(back);
+ EXPECT_TRUE(value == forth);
+ }
+}
+#endif
TEST(LlvmLibcUIntClassTest, BasicInit) {
LL_UInt128 half_val(12345);
@@ -634,3 +684,5 @@ TEST(LlvmLibcUIntClassTest, ConstructorFromUInt128Tests) {
}
#endif // __SIZEOF_INT128__
+
+} // namespace LIBC_NAMESPACE
diff --git a/utils/bazel/llvm-project-overlay/libc/test/src/__support/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/test/src/__support/BUILD.bazel
index a973e6541da015..f775183296636e 100644
--- a/utils/bazel/llvm-project-overlay/libc/test/src/__support/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/test/src/__support/BUILD.bazel
@@ -74,7 +74,10 @@ libc_test(
name = "uint_test",
srcs = ["uint_test.cpp"],
deps = [
+ "//libc:__support_cpp_bit",
"//libc:__support_cpp_optional",
+ "//libc:__support_cpp_type_traits",
+ "//libc:__support_macros_properties_float",
"//libc:__support_uint",
],
)
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Fix #74258
This is a reland of #74837, the error went unnoticed because it compiles fine on
clang-16 but not on clang-12 which is the version used on the buildbots.
The fix was to explicitly initialize
BigIntvariables inconstexproperations:BigInt<Bits, Signed> result(0);instead ofBigInt<Bits, Signed> result;