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error: use of unknown builtin '__builtin_ia32_pause' #9058

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ryandesign opened this issue Jun 28, 2022 · 3 comments
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error: use of unknown builtin '__builtin_ia32_pause' #9058

ryandesign opened this issue Jun 28, 2022 · 3 comments
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@ryandesign
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@ryandesign ryandesign commented Jun 28, 2022

I did this

Compile curl

I expected the following

Successful compile

curl/libcurl version

7.84.0

operating system

OS X 10.10
Xcode 7.2.1
Apple LLVM version 7.0.2 (clang-700.1.81)

In file included from easy.c:89:
../lib/easy_lock.h:52:7: error: use of unknown builtin '__builtin_ia32_pause' [-Wimplicit-function-declaration]
      __builtin_ia32_pause();
      ^

https://build.macports.org/builders/ports-10.10_x86_64-builder/builds/188168/steps/install-port/logs/stdio

This problem does not occur on later system such as:

OS X 10.11
Xcode 8.2.1
Apple LLVM version 8.0.0 (clang-800.0.42.1)

@jay
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@jay jay commented Jun 28, 2022

Does this work:

diff --git a/lib/easy_lock.h b/lib/easy_lock.h
index 07c85c5..15c6c07 100644
--- a/lib/easy_lock.h
+++ b/lib/easy_lock.h
@@ -52,7 +52,11 @@ static inline void curl_simple_lock_lock(curl_simple_lock *lock)
     while(atomic_load_explicit(lock, memory_order_relaxed)) {
       /* Reduce load (not mandatory) */
 #if defined(__i386__) || defined(__x86_64__)
+#if defined(__GNUC__) && !defined(__llvm__)
       __builtin_ia32_pause();
+#else
+      __asm__ volatile("pause");
+#endif
 #elif defined(__aarch64__)
       __asm__ volatile("yield" ::: "memory");
 #elif defined(HAVE_SCHED_YIELD)

@jay jay added the build label Jun 28, 2022
@jmroot
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@jmroot jmroot commented Jun 28, 2022

You could keep using the builtin with clang versions that support it by checking for it with __has_builtin, as described here: https://clang.llvm.org/docs/LanguageExtensions.html#feature-checking-macros

@bagder
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@bagder bagder commented Jun 28, 2022

Then perhaps (also available as #9062)

diff --git a/lib/easy_lock.h b/lib/easy_lock.h
index 07c85c5ff..18d90a4dc 100644
--- a/lib/easy_lock.h
+++ b/lib/easy_lock.h
@@ -41,19 +41,29 @@
 #endif
 
 #define curl_simple_lock atomic_bool
 #define CURL_SIMPLE_LOCK_INIT false
 
+/* a clang-thing */
+#ifndef __has_builtin
+#define __has_builtin(x) 0
+#endif
+
+#if (defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))) || \
+  __has_builtin(__builtin_ia32_pause)
+#define HAVE_BUILTIN_IA32_PAUSE
+#endif
+
 static inline void curl_simple_lock_lock(curl_simple_lock *lock)
 {
   for(;;) {
     if(!atomic_exchange_explicit(lock, true, memory_order_acquire))
       break;
     /* Reduce cache coherency traffic */
     while(atomic_load_explicit(lock, memory_order_relaxed)) {
       /* Reduce load (not mandatory) */
-#if defined(__i386__) || defined(__x86_64__)
+#ifdef HAVE_BUILTIN_IA32_PAUSE
       __builtin_ia32_pause();
 #elif defined(__aarch64__)
       __asm__ volatile("yield" ::: "memory");
 #elif defined(HAVE_SCHED_YIELD)
       sched_yield();

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4 participants