Get rid of -fno-tree-dominator-opts

This option is deprecated and removed, so we
cannot rely on it. Additionally, don't rely on
`fancy_return_zero' and use inline assembly to
generate a proper zero return value instead.

4 files changed, 8 insertions, 57 deletions

diff --git a/platform/switch_aarch64_gcc.h b/platform/switch_aarch64_gcc.h
index 0c4e3cc..d6a6a52 100644
--- a/platform/switch_aarch64_gcc.h
+++ b/platform/switch_aarch64_gcc.h
@@ -20,18 +20,10 @@
                      "v8", "v9", "v10", "v11", \
                      "v12", "v13", "v14", "v15"
 
-/* See below for the purpose of this function.  */
-__attribute__((noinline, noclone)) int fancy_return_zero(void);
-__attribute__((noinline, noclone)) int
-fancy_return_zero(void)
-{
-  return 0;
-}
-
 static int
 slp_switch(void)
 {
-	int err = 0;
+	int err;
 	void *fp;
         register long *stackref, stsizediff;
         __asm__ volatile ("" : : : REGS_TO_SAVE);
@@ -41,7 +33,7 @@ slp_switch(void)
                 SLP_SAVE_STATE(stackref, stsizediff);
                 __asm__ volatile (
                     "add sp,sp,%0\n"
-		    "add x29,x29,%0\n"
+                    "add x29,x29,%0\n"
                     :
                     : "r" (stsizediff)
                     );
@@ -66,9 +58,9 @@ slp_switch(void)
 		   stack space), and the simplest is to call a function
 		   that returns an unknown value (which happens to be zero),
 		   so the saved/restored value is unused.  */
-		err = fancy_return_zero();
+           __asm__ volatile ("mov x0, #0" : "=x0" (err));
         }
-	__asm__ volatile ("ldr x29, %0" : : "m" (fp) :);
+        __asm__ volatile ("ldr x29, %0" : : "m" (fp) :);
         __asm__ volatile ("" : : : REGS_TO_SAVE);
         return err;
 }
diff --git a/platform/switch_amd64_unix.h b/platform/switch_amd64_unix.h
index 05b34b6..16b99b7 100644
--- a/platform/switch_amd64_unix.h
+++ b/platform/switch_amd64_unix.h
@@ -36,18 +36,10 @@
 
 #define REGS_TO_SAVE "r12", "r13", "r14", "r15"
 
-/* See switch_aarch64_gcc.h for the purpose of this function  */
-__attribute__((noinline, noclone)) int fancy_return_zero(void);
-__attribute__((noinline, noclone)) int
-fancy_return_zero(void)
-{
-  return 0;
-}
-
 static int
 slp_switch(void)
 {
-    int err = 0;
+    int err;
     void* rbp;
     void* rbx;
     unsigned int csr;
@@ -68,7 +60,7 @@ slp_switch(void)
             : "r" (stsizediff)
             );
         SLP_RESTORE_STATE();
-        err = fancy_return_zero();
+        __asm__ volatile ("xorq %%rax, %%rax" : "=a" (err));
     }
     __asm__ volatile ("movq %0, %%rbx" : : "m" (rbx));
     __asm__ volatile ("movq %0, %%rbp" : : "m" (rbp));
diff --git a/platform/switch_x86_unix.h b/platform/switch_x86_unix.h
index b59793b..3a95186 100644
--- a/platform/switch_x86_unix.h
+++ b/platform/switch_x86_unix.h
@@ -42,18 +42,10 @@
 # define ATTR_NOCLONE
 #endif
 
-/* See below for the purpose of this function.  */
-__attribute__((noinline)) ATTR_NOCLONE int fancy_return_zero(void);
-__attribute__((noinline)) ATTR_NOCLONE int
-fancy_return_zero(void)
-{
-  return 0;
-}
-
 static int
 slp_switch(void)
 {
-    int err = 0;
+    int err;
 #ifdef _WIN32
     void *seh;
 #endif
@@ -82,7 +74,7 @@ slp_switch(void)
             : "r" (stsizediff)
             );
         SLP_RESTORE_STATE();
-        err = fancy_return_zero();
+        __asm__ volatile ("xorl %%eax, %%eax" : "=a" (err));
     }
 #ifdef _WIN32
     __asm__ volatile (
diff --git a/setup.py b/setup.py
index 23e94df..0d7181e 100755
--- a/setup.py
+++ b/setup.py
@@ -54,33 +54,9 @@ else:
         extra_objects=extra_objects,
         depends=['greenlet.h', 'slp_platformselect.h'] + _find_platform_headers())]
 
-from my_build_ext import build_ext as _build_ext
 from distutils.core import Command
 
 
-class build_ext(_build_ext):
-    def configure_compiler(self):
-        compiler = self.compiler
-        if compiler.__class__.__name__ != "UnixCCompiler":
-            return
-
-        compiler.compiler_so += ["-fno-tree-dominator-opts"]
-        tmpdir = tempfile.mkdtemp()
-
-        try:
-            simple_c = os.path.join(tmpdir, "simple.c")
-            open(simple_c, "w").write("void foo(){}")
-            compiler.compile([simple_c], output_dir=tmpdir)
-        except Exception:
-            del compiler.compiler_so[-1]
-
-        shutil.rmtree(tmpdir)
-
-    def build_extensions(self):
-        self.configure_compiler()
-        _build_ext.build_extensions(self)
-
-
 setup(
     name="greenlet",
     version='0.4.2',
@@ -93,7 +69,6 @@ setup(
     platforms=['any'],
     headers=headers,
     ext_modules=ext_modules,
-    cmdclass=dict(build_ext=build_ext),
     classifiers=[
         'Intended Audience :: Developers',
         'License :: OSI Approved :: MIT License',