Export of internal Abseil changes.

--
821196cfb2a3b943ffdc4c9e75daec92d7ffb28b by Abseil Team <absl-team@google.com>:

Performance improvements

PiperOrigin-RevId: 212668992

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704858e2e767016bad27d53eec01d9d48e546b23 by Abseil Team <absl-team@google.com>:

Low-level Portability enchancements for Abseil Mutex on WebAssembly.

Emscripten Pthreads do not use signals, so remove use of pthread_sigmask or
other async-signal-safe related handling code.

PiperOrigin-RevId: 212527958

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be3e38cb4d493b755132d20c8c2d1a51e45d5449 by Jon Cohen <cohenjon@google.com>:

Internal change.

PiperOrigin-RevId: 212523797
GitOrigin-RevId: 821196cfb2a3b943ffdc4c9e75daec92d7ffb28b
Change-Id: I5694e23e4e09364a15dd6fc4e2e3f15e38835687

absl/strings/str_format_test.cc

@@ -601,3 +601,39 @@ TEST_F(ParsedFormatTest, RegressionMixPositional) {
 
 }  // namespace
 }  // namespace absl
+
+// Some codegen thunks that we can use to easily dump the generated assembly for
+// different StrFormat calls.
+
+inline std::string CodegenAbslStrFormatInt(int i) {
+  return absl::StrFormat("%d", i);
+}
+
+inline std::string CodegenAbslStrFormatIntStringInt64(int i, const std::string& s,
+                                                 int64_t i64) {
+  return absl::StrFormat("%d %s %d", i, s, i64);
+}
+
+inline void CodegenAbslStrAppendFormatInt(std::string* out, int i) {
+  absl::StrAppendFormat(out, "%d", i);
+}
+
+inline void CodegenAbslStrAppendFormatIntStringInt64(std::string* out, int i,
+                                                     const std::string& s,
+                                                     int64_t i64) {
+  absl::StrAppendFormat(out, "%d %s %d", i, s, i64);
+}
+
+auto absl_internal_str_format_force_codegen_funcs = std::make_tuple(
+    CodegenAbslStrFormatInt, CodegenAbslStrFormatIntStringInt64,
+    CodegenAbslStrAppendFormatInt, CodegenAbslStrAppendFormatIntStringInt64);
+
+bool absl_internal_str_format_force_codegen_always_false;
+// Force the compiler to generate the functions by making it look like we
+// escape the function pointers.
+// It can't statically know that
+// absl_internal_str_format_force_codegen_always_false is not changed by someone
+// else.
+bool absl_internal_str_format_force_codegen =
+    absl_internal_str_format_force_codegen_always_false &&
+    printf("%p", &absl_internal_str_format_force_codegen_funcs) == 0;