summaryrefslogtreecommitdiff
path: root/absl/strings/internal/str_format/convert_test.cc
diff options
context:
space:
mode:
Diffstat (limited to 'absl/strings/internal/str_format/convert_test.cc')
-rw-r--r--absl/strings/internal/str_format/convert_test.cc230
1 files changed, 221 insertions, 9 deletions
diff --git a/absl/strings/internal/str_format/convert_test.cc b/absl/strings/internal/str_format/convert_test.cc
index e37d0546..488d4cd4 100644
--- a/absl/strings/internal/str_format/convert_test.cc
+++ b/absl/strings/internal/str_format/convert_test.cc
@@ -12,6 +12,7 @@
#include "gtest/gtest.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/strings/internal/str_format/bind.h"
+#include "absl/strings/match.h"
#include "absl/types/optional.h"
namespace absl {
@@ -19,6 +20,13 @@ ABSL_NAMESPACE_BEGIN
namespace str_format_internal {
namespace {
+struct NativePrintfTraits {
+ bool hex_float_has_glibc_rounding;
+ bool hex_float_prefers_denormal_repr;
+ bool hex_float_uses_minimal_precision_when_not_specified;
+ bool hex_float_optimizes_leading_digit_bit_count;
+};
+
template <typename T, size_t N>
size_t ArraySize(T (&)[N]) {
return N;
@@ -118,6 +126,63 @@ std::string StrPrint(const char *format, ...) {
return result;
}
+NativePrintfTraits VerifyNativeImplementationImpl() {
+ NativePrintfTraits result;
+
+ // >>> hex_float_has_glibc_rounding. To have glibc's rounding behavior we need
+ // to meet three requirements:
+ //
+ // - The threshold for rounding up is 8 (for e.g. MSVC uses 9).
+ // - If the digits lower than than the 8 are non-zero then we round up.
+ // - If the digits lower than the 8 are all zero then we round toward even.
+ //
+ // The numbers below represent all the cases covering {below,at,above} the
+ // threshold (8) with both {zero,non-zero} lower bits and both {even,odd}
+ // preceding digits.
+ const double d0079 = 65657.0; // 0x1.0079p+16
+ const double d0179 = 65913.0; // 0x1.0179p+16
+ const double d0080 = 65664.0; // 0x1.0080p+16
+ const double d0180 = 65920.0; // 0x1.0180p+16
+ const double d0081 = 65665.0; // 0x1.0081p+16
+ const double d0181 = 65921.0; // 0x1.0181p+16
+ result.hex_float_has_glibc_rounding =
+ StartsWith(StrPrint("%.2a", d0079), "0x1.00") &&
+ StartsWith(StrPrint("%.2a", d0179), "0x1.01") &&
+ StartsWith(StrPrint("%.2a", d0080), "0x1.00") &&
+ StartsWith(StrPrint("%.2a", d0180), "0x1.02") &&
+ StartsWith(StrPrint("%.2a", d0081), "0x1.01") &&
+ StartsWith(StrPrint("%.2a", d0181), "0x1.02");
+
+ // >>> hex_float_prefers_denormal_repr. Formatting `denormal` on glibc yields
+ // "0x0.0000000000001p-1022", whereas on std libs that don't use denormal
+ // representation it would either be 0x1p-1074 or 0x1.0000000000000-1074.
+ const double denormal = std::numeric_limits<double>::denorm_min();
+ result.hex_float_prefers_denormal_repr =
+ StartsWith(StrPrint("%a", denormal), "0x0.0000000000001");
+
+ // >>> hex_float_uses_minimal_precision_when_not_specified. Some (non-glibc)
+ // libs will format the following as "0x1.0079000000000p+16".
+ result.hex_float_uses_minimal_precision_when_not_specified =
+ (StrPrint("%a", d0079) == "0x1.0079p+16");
+
+ // >>> hex_float_optimizes_leading_digit_bit_count. The number 1.5, when
+ // formatted by glibc should yield "0x1.8p+0" for `double` and "0xcp-3" for
+ // `long double`, i.e., number of bits in the leading digit is adapted to the
+ // number of bits in the mantissa.
+ const double d_15 = 1.5;
+ const long double ld_15 = 1.5;
+ result.hex_float_optimizes_leading_digit_bit_count =
+ StartsWith(StrPrint("%a", d_15), "0x1.8") &&
+ StartsWith(StrPrint("%La", ld_15), "0xc");
+
+ return result;
+}
+
+const NativePrintfTraits &VerifyNativeImplementation() {
+ static NativePrintfTraits native_traits = VerifyNativeImplementationImpl();
+ return native_traits;
+}
+
class FormatConvertTest : public ::testing::Test { };
template <typename T>
@@ -476,6 +541,7 @@ TEST_F(FormatConvertTest, Uint128) {
template <typename Floating>
void TestWithMultipleFormatsHelper(const std::vector<Floating> &floats) {
+ const NativePrintfTraits &native_traits = VerifyNativeImplementation();
// Reserve the space to ensure we don't allocate memory in the output itself.
std::string str_format_result;
str_format_result.reserve(1 << 20);
@@ -493,13 +559,23 @@ void TestWithMultipleFormatsHelper(const std::vector<Floating> &floats) {
'e', 'E'}) {
std::string fmt_str = std::string(fmt) + f;
- if (fmt == absl::string_view("%.5000") && f != 'f' && f != 'F') {
+ if (fmt == absl::string_view("%.5000") && f != 'f' && f != 'F' &&
+ f != 'a' && f != 'A') {
// This particular test takes way too long with snprintf.
// Disable for the case we are not implementing natively.
continue;
}
+ if ((f == 'a' || f == 'A') &&
+ !native_traits.hex_float_has_glibc_rounding) {
+ continue;
+ }
+
for (Floating d : floats) {
+ if (!native_traits.hex_float_prefers_denormal_repr &&
+ (f == 'a' || f == 'A') && std::fpclassify(d) == FP_SUBNORMAL) {
+ continue;
+ }
int i = -10;
FormatArgImpl args[2] = {FormatArgImpl(d), FormatArgImpl(i)};
UntypedFormatSpecImpl format(fmt_str);
@@ -766,6 +842,111 @@ TEST_F(FormatConvertTest, DoubleRound) {
"1837869002408041296803276054561138153076171875");
}
+TEST_F(FormatConvertTest, DoubleRoundA) {
+ const NativePrintfTraits &native_traits = VerifyNativeImplementation();
+ std::string s;
+ const auto format = [&](const char *fmt, double d) -> std::string & {
+ s.clear();
+ FormatArgImpl args[1] = {FormatArgImpl(d)};
+ AppendPack(&s, UntypedFormatSpecImpl(fmt), absl::MakeSpan(args));
+ if (native_traits.hex_float_has_glibc_rounding) {
+ EXPECT_EQ(StrPrint(fmt, d), s);
+ }
+ return s;
+ };
+
+ // 0x1.00018000p+100
+ const double on_boundary_odd = 1267679614447900152596896153600.0;
+ EXPECT_EQ(format("%.0a", on_boundary_odd), "0x1p+100");
+ EXPECT_EQ(format("%.1a", on_boundary_odd), "0x1.0p+100");
+ EXPECT_EQ(format("%.2a", on_boundary_odd), "0x1.00p+100");
+ EXPECT_EQ(format("%.3a", on_boundary_odd), "0x1.000p+100");
+ EXPECT_EQ(format("%.4a", on_boundary_odd), "0x1.0002p+100"); // round
+ EXPECT_EQ(format("%.5a", on_boundary_odd), "0x1.00018p+100");
+ EXPECT_EQ(format("%.6a", on_boundary_odd), "0x1.000180p+100");
+
+ // 0x1.00028000p-2
+ const double on_boundary_even = 0.250009536743164062500;
+ EXPECT_EQ(format("%.0a", on_boundary_even), "0x1p-2");
+ EXPECT_EQ(format("%.1a", on_boundary_even), "0x1.0p-2");
+ EXPECT_EQ(format("%.2a", on_boundary_even), "0x1.00p-2");
+ EXPECT_EQ(format("%.3a", on_boundary_even), "0x1.000p-2");
+ EXPECT_EQ(format("%.4a", on_boundary_even), "0x1.0002p-2"); // no round
+ EXPECT_EQ(format("%.5a", on_boundary_even), "0x1.00028p-2");
+ EXPECT_EQ(format("%.6a", on_boundary_even), "0x1.000280p-2");
+
+ // 0x1.00018001p+1
+ const double slightly_over = 2.00004577683284878730773925781250;
+ EXPECT_EQ(format("%.0a", slightly_over), "0x1p+1");
+ EXPECT_EQ(format("%.1a", slightly_over), "0x1.0p+1");
+ EXPECT_EQ(format("%.2a", slightly_over), "0x1.00p+1");
+ EXPECT_EQ(format("%.3a", slightly_over), "0x1.000p+1");
+ EXPECT_EQ(format("%.4a", slightly_over), "0x1.0002p+1");
+ EXPECT_EQ(format("%.5a", slightly_over), "0x1.00018p+1");
+ EXPECT_EQ(format("%.6a", slightly_over), "0x1.000180p+1");
+
+ // 0x1.00017fffp+0
+ const double slightly_under = 1.000022887950763106346130371093750;
+ EXPECT_EQ(format("%.0a", slightly_under), "0x1p+0");
+ EXPECT_EQ(format("%.1a", slightly_under), "0x1.0p+0");
+ EXPECT_EQ(format("%.2a", slightly_under), "0x1.00p+0");
+ EXPECT_EQ(format("%.3a", slightly_under), "0x1.000p+0");
+ EXPECT_EQ(format("%.4a", slightly_under), "0x1.0001p+0");
+ EXPECT_EQ(format("%.5a", slightly_under), "0x1.00018p+0");
+ EXPECT_EQ(format("%.6a", slightly_under), "0x1.000180p+0");
+ EXPECT_EQ(format("%.7a", slightly_under), "0x1.0001800p+0");
+
+ // 0x1.1b3829ac28058p+3
+ const double hex_value = 8.85060580848964661981881363317370414733886718750;
+ EXPECT_EQ(format("%.0a", hex_value), "0x1p+3");
+ EXPECT_EQ(format("%.1a", hex_value), "0x1.2p+3");
+ EXPECT_EQ(format("%.2a", hex_value), "0x1.1bp+3");
+ EXPECT_EQ(format("%.3a", hex_value), "0x1.1b4p+3");
+ EXPECT_EQ(format("%.4a", hex_value), "0x1.1b38p+3");
+ EXPECT_EQ(format("%.5a", hex_value), "0x1.1b383p+3");
+ EXPECT_EQ(format("%.6a", hex_value), "0x1.1b382ap+3");
+ EXPECT_EQ(format("%.7a", hex_value), "0x1.1b3829bp+3");
+ EXPECT_EQ(format("%.8a", hex_value), "0x1.1b3829acp+3");
+ EXPECT_EQ(format("%.9a", hex_value), "0x1.1b3829ac3p+3");
+ EXPECT_EQ(format("%.10a", hex_value), "0x1.1b3829ac28p+3");
+ EXPECT_EQ(format("%.11a", hex_value), "0x1.1b3829ac280p+3");
+ EXPECT_EQ(format("%.12a", hex_value), "0x1.1b3829ac2806p+3");
+ EXPECT_EQ(format("%.13a", hex_value), "0x1.1b3829ac28058p+3");
+ EXPECT_EQ(format("%.14a", hex_value), "0x1.1b3829ac280580p+3");
+ EXPECT_EQ(format("%.15a", hex_value), "0x1.1b3829ac2805800p+3");
+ EXPECT_EQ(format("%.16a", hex_value), "0x1.1b3829ac28058000p+3");
+ EXPECT_EQ(format("%.17a", hex_value), "0x1.1b3829ac280580000p+3");
+ EXPECT_EQ(format("%.18a", hex_value), "0x1.1b3829ac2805800000p+3");
+ EXPECT_EQ(format("%.19a", hex_value), "0x1.1b3829ac28058000000p+3");
+ EXPECT_EQ(format("%.20a", hex_value), "0x1.1b3829ac280580000000p+3");
+ EXPECT_EQ(format("%.21a", hex_value), "0x1.1b3829ac2805800000000p+3");
+
+ // 0x1.0818283848586p+3
+ const double hex_value2 = 8.2529488658208371987257123691961169242858886718750;
+ EXPECT_EQ(format("%.0a", hex_value2), "0x1p+3");
+ EXPECT_EQ(format("%.1a", hex_value2), "0x1.1p+3");
+ EXPECT_EQ(format("%.2a", hex_value2), "0x1.08p+3");
+ EXPECT_EQ(format("%.3a", hex_value2), "0x1.082p+3");
+ EXPECT_EQ(format("%.4a", hex_value2), "0x1.0818p+3");
+ EXPECT_EQ(format("%.5a", hex_value2), "0x1.08183p+3");
+ EXPECT_EQ(format("%.6a", hex_value2), "0x1.081828p+3");
+ EXPECT_EQ(format("%.7a", hex_value2), "0x1.0818284p+3");
+ EXPECT_EQ(format("%.8a", hex_value2), "0x1.08182838p+3");
+ EXPECT_EQ(format("%.9a", hex_value2), "0x1.081828385p+3");
+ EXPECT_EQ(format("%.10a", hex_value2), "0x1.0818283848p+3");
+ EXPECT_EQ(format("%.11a", hex_value2), "0x1.08182838486p+3");
+ EXPECT_EQ(format("%.12a", hex_value2), "0x1.081828384858p+3");
+ EXPECT_EQ(format("%.13a", hex_value2), "0x1.0818283848586p+3");
+ EXPECT_EQ(format("%.14a", hex_value2), "0x1.08182838485860p+3");
+ EXPECT_EQ(format("%.15a", hex_value2), "0x1.081828384858600p+3");
+ EXPECT_EQ(format("%.16a", hex_value2), "0x1.0818283848586000p+3");
+ EXPECT_EQ(format("%.17a", hex_value2), "0x1.08182838485860000p+3");
+ EXPECT_EQ(format("%.18a", hex_value2), "0x1.081828384858600000p+3");
+ EXPECT_EQ(format("%.19a", hex_value2), "0x1.0818283848586000000p+3");
+ EXPECT_EQ(format("%.20a", hex_value2), "0x1.08182838485860000000p+3");
+ EXPECT_EQ(format("%.21a", hex_value2), "0x1.081828384858600000000p+3");
+}
+
// We don't actually store the results. This is just to exercise the rest of the
// machinery.
struct NullSink {
@@ -797,6 +978,7 @@ TEST_F(FormatConvertTest, LongDouble) {
// implementation against the native one there.
return;
#endif // _MSC_VER
+ const NativePrintfTraits &native_traits = VerifyNativeImplementation();
const char *const kFormats[] = {"%", "%.3", "%8.5", "%9", "%.5000",
"%.60", "%+", "% ", "%-10"};
@@ -839,12 +1021,20 @@ TEST_F(FormatConvertTest, LongDouble) {
'e', 'E'}) {
std::string fmt_str = std::string(fmt) + 'L' + f;
- if (fmt == absl::string_view("%.5000") && f != 'f' && f != 'F') {
+ if (fmt == absl::string_view("%.5000") && f != 'f' && f != 'F' &&
+ f != 'a' && f != 'A') {
// This particular test takes way too long with snprintf.
// Disable for the case we are not implementing natively.
continue;
}
+ if (f == 'a' || f == 'A') {
+ if (!native_traits.hex_float_has_glibc_rounding ||
+ !native_traits.hex_float_optimizes_leading_digit_bit_count) {
+ continue;
+ }
+ }
+
for (auto d : doubles) {
FormatArgImpl arg(d);
UntypedFormatSpecImpl format(fmt_str);
@@ -860,6 +1050,7 @@ TEST_F(FormatConvertTest, LongDouble) {
}
TEST_F(FormatConvertTest, IntAsDouble) {
+ const NativePrintfTraits &native_traits = VerifyNativeImplementation();
const int kMin = std::numeric_limits<int>::min();
const int kMax = std::numeric_limits<int>::max();
const int ia[] = {
@@ -875,14 +1066,16 @@ TEST_F(FormatConvertTest, IntAsDouble) {
const char *fmt;
};
const double dx = static_cast<double>(fx);
- const Expectation kExpect[] = {
- { __LINE__, StrPrint("%f", dx), "%f" },
- { __LINE__, StrPrint("%12f", dx), "%12f" },
- { __LINE__, StrPrint("%.12f", dx), "%.12f" },
- { __LINE__, StrPrint("%12a", dx), "%12a" },
- { __LINE__, StrPrint("%.12a", dx), "%.12a" },
+ std::vector<Expectation> expect = {
+ {__LINE__, StrPrint("%f", dx), "%f"},
+ {__LINE__, StrPrint("%12f", dx), "%12f"},
+ {__LINE__, StrPrint("%.12f", dx), "%.12f"},
+ {__LINE__, StrPrint("%.12a", dx), "%.12a"},
};
- for (const Expectation &e : kExpect) {
+ if (native_traits.hex_float_uses_minimal_precision_when_not_specified) {
+ expect.push_back({__LINE__, StrPrint("%12a", dx), "%12a"});
+ }
+ for (const Expectation &e : expect) {
SCOPED_TRACE(e.line);
SCOPED_TRACE(e.fmt);
UntypedFormatSpecImpl format(e.fmt);
@@ -927,6 +1120,25 @@ TEST_F(FormatConvertTest, ExpectedFailures) {
EXPECT_TRUE(FormatFails("%*d", ""));
}
+// Sanity check to make sure that we are testing what we think we're testing on
+// e.g. the x86_64+glibc platform.
+TEST_F(FormatConvertTest, GlibcHasCorrectTraits) {
+#if !defined(__GLIBC__) || !defined(__x86_64__)
+ return;
+#endif
+ const NativePrintfTraits &native_traits = VerifyNativeImplementation();
+ // If one of the following tests break then it is either because the above PP
+ // macro guards failed to exclude a new platform (likely) or because something
+ // has changed in the implemention of glibc sprintf float formatting behavior.
+ // If the latter, then the code that computes these flags needs to be
+ // revisited and/or possibly the StrFormat implementation.
+ EXPECT_TRUE(native_traits.hex_float_has_glibc_rounding);
+ EXPECT_TRUE(native_traits.hex_float_prefers_denormal_repr);
+ EXPECT_TRUE(
+ native_traits.hex_float_uses_minimal_precision_when_not_specified);
+ EXPECT_TRUE(native_traits.hex_float_optimizes_leading_digit_bit_count);
+}
+
} // namespace
} // namespace str_format_internal
ABSL_NAMESPACE_END
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-03 14:39:40 +0000