Export of internal Abseil changes

--
1609589925459c2c0b2a17912c0d65227f709db9 by Abseil Team <absl-team@google.com>:

Clarify the "Potential Mutex deadlock" reason message.

PiperOrigin-RevId: 351367862

--
88bf28863db2c2d2d48767c3e4dfab6a48bdff79 by Abseil Team <absl-team@google.com>:

Print CPU number is fault handler.

This CL adds code to print CPU number inside the fault handler.  This is only supported on Linux.  The CPU number is also a hint only.  There is no guarantee that it is indeed the CPU on which a fault happened.

PiperOrigin-RevId: 351238373

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66a9c8e44b5744fec1ca0d7b8db7e1d50772d9a2 by Samuel Benzaquen <sbenza@google.com>:

Add better error message for ODR violations of flags.

PiperOrigin-RevId: 351197423

--
6efd1efb341563148dd43255aaa4bf959dfd9554 by Chris Kennelly <ckennelly@google.com>:

Assume bitwise builtins are available on GCC.

These are long-standing builtins but are not consistently detected by
ABSL_HAVE_BUILTIN.

PiperOrigin-RevId: 350814036
GitOrigin-RevId: 1609589925459c2c0b2a17912c0d65227f709db9
Change-Id: Ied3fd2f135187f2c316b403fba45f3bbaea54138

2 files changed, 27 insertions, 10 deletions

diff --git a/absl/numeric/bits_test.cc b/absl/numeric/bits_test.cc
index 8bf7bc9f..7c942aae 100644
--- a/absl/numeric/bits_test.cc
+++ b/absl/numeric/bits_test.cc
@@ -560,6 +560,14 @@ TEST(IntegralPowersOfTwo, Width) {
   }
 }
 
+// On GCC and Clang, anticiapte that implementations will be constexpr
+#if defined(__GNUC__)
+static_assert(ABSL_INTERNAL_HAS_CONSTEXPR_POPCOUNT,
+              "popcount should be constexpr");
+static_assert(ABSL_INTERNAL_HAS_CONSTEXPR_CLZ, "clz should be constexpr");
+static_assert(ABSL_INTERNAL_HAS_CONSTEXPR_CTZ, "ctz should be constexpr");
+#endif
+
 }  // namespace
 ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/numeric/internal/bits.h b/absl/numeric/internal/bits.h
index af45700f..e51941d7 100644
--- a/absl/numeric/internal/bits.h
+++ b/absl/numeric/internal/bits.h
@@ -28,8 +28,15 @@
 #include "absl/base/attributes.h"
 #include "absl/base/config.h"
 
-#if ABSL_HAVE_BUILTIN(__builtin_popcountl) && \
-    ABSL_HAVE_BUILTIN(__builtin_popcountll)
+#if defined(__GNUC__) && !defined(__clang__)
+// GCC
+#define ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(x) 1
+#else
+#define ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(x) ABSL_HAVE_BUILTIN(x)
+#endif
+
+#if ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_popcountl) && \
+    ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_popcountll)
 #define ABSL_INTERNAL_CONSTEXPR_POPCOUNT constexpr
 #define ABSL_INTERNAL_HAS_CONSTEXPR_POPCOUNT 1
 #else
@@ -37,7 +44,8 @@
 #define ABSL_INTERNAL_HAS_CONSTEXPR_POPCOUNT 0
 #endif
 
-#if ABSL_HAVE_BUILTIN(__builtin_clz) && ABSL_HAVE_BUILTIN(__builtin_clzll)
+#if ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_clz) && \
+    ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_clzll)
 #define ABSL_INTERNAL_CONSTEXPR_CLZ constexpr
 #define ABSL_INTERNAL_HAS_CONSTEXPR_CLZ 1
 #else
@@ -45,7 +53,8 @@
 #define ABSL_INTERNAL_HAS_CONSTEXPR_CLZ 0
 #endif
 
-#if ABSL_HAVE_BUILTIN(__builtin_ctz) && ABSL_HAVE_BUILTIN(__builtin_ctzll)
+#if ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_ctz) && \
+    ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_ctzll)
 #define ABSL_INTERNAL_CONSTEXPR_CTZ constexpr
 #define ABSL_INTERNAL_HAS_CONSTEXPR_CTZ 1
 #else
@@ -85,7 +94,7 @@ ABSL_MUST_USE_RESULT ABSL_ATTRIBUTE_ALWAYS_INLINE constexpr T RotateLeft(
 
 ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_POPCOUNT inline int
 Popcount32(uint32_t x) noexcept {
-#if ABSL_HAVE_BUILTIN(__builtin_popcount)
+#if ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_popcount)
   static_assert(sizeof(unsigned int) == sizeof(x),
                 "__builtin_popcount does not take 32-bit arg");
   return __builtin_popcount(x);
@@ -98,7 +107,7 @@ Popcount32(uint32_t x) noexcept {
 
 ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_POPCOUNT inline int
 Popcount64(uint64_t x) noexcept {
-#if ABSL_HAVE_BUILTIN(__builtin_popcountll)
+#if ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_popcountll)
   static_assert(sizeof(unsigned long long) == sizeof(x),  // NOLINT(runtime/int)
                 "__builtin_popcount does not take 64-bit arg");
   return __builtin_popcountll(x);
@@ -122,7 +131,7 @@ Popcount(T x) noexcept {
 
 ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CLZ inline int
 CountLeadingZeroes32(uint32_t x) {
-#if ABSL_HAVE_BUILTIN(__builtin_clz)
+#if ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_clz)
   // Use __builtin_clz, which uses the following instructions:
   //  x86: bsr, lzcnt
   //  ARM64: clz
@@ -169,7 +178,7 @@ CountLeadingZeroes16(uint16_t x) {
 
 ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CLZ inline int
 CountLeadingZeroes64(uint64_t x) {
-#if ABSL_HAVE_BUILTIN(__builtin_clzll)
+#if ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_clzll)
   // Use __builtin_clzll, which uses the following instructions:
   //  x86: bsr, lzcnt
   //  ARM64: clz
@@ -240,7 +249,7 @@ CountLeadingZeroes(T x) {
 
 ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CTZ inline int
 CountTrailingZeroesNonzero32(uint32_t x) {
-#if ABSL_HAVE_BUILTIN(__builtin_ctz)
+#if ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_ctz)
   static_assert(sizeof(unsigned int) == sizeof(x),
                 "__builtin_ctz does not take 32-bit arg");
   return __builtin_ctz(x);
@@ -262,7 +271,7 @@ CountTrailingZeroesNonzero32(uint32_t x) {
 
 ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CTZ inline int
 CountTrailingZeroesNonzero64(uint64_t x) {
-#if ABSL_HAVE_BUILTIN(__builtin_ctzll)
+#if ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_ctzll)
   static_assert(sizeof(unsigned long long) == sizeof(x),  // NOLINT(runtime/int)
                 "__builtin_ctzll does not take 64-bit arg");
   return __builtin_ctzll(x);