Add extension 'gnu_asm_goto_with_outputs'

[void]

Summary

Clang now supports GNU's asm goto with outputs.

[void]

Use GNU asm predicate for the "asm goto with outputs" extension.

[nickdesaulniers]

Great idea; thanks for the patch! Needs documentation. :)

clang/test/Parser/asm-goto-with-outputs.c

8

probably don't need a bunch of test cases, just the check for the preprocessor define? In that case, why don't you just add the above to an existing asm goto test?

[void]

Move extension test to exsiting test.

[void]

In D73319#1842900, @nickdesaulniers wrote:

Great idea; thanks for the patch! Needs documentation. :)

I can't find a place for documentation of extensions, at least not the names of extensions like gnu_asm.

clang/test/Parser/asm-goto-with-outputs.c

8

Sure. done.

[void]

Add description of "gnu_asm_goto_with_outputs" to the language extensions doc.

[nickdesaulniers]

In D73319#1842951, @void wrote:

In D73319#1842900, @nickdesaulniers wrote:

Great idea; thanks for the patch! Needs documentation. :)

I can't find a place for documentation of extensions, at least not the names of extensions like gnu_asm.

How about https://clang.llvm.org/docs/LanguageExtensions.html#checks-for-standard-language-features ? Then we can add both gnu_asm and gnu_asm_goto_with_outputs.

clang/test/Parser/asm-goto.c

9 ↗

(On Diff #240663)

ah, sorry, maybe a test that makes use of asm goto + output constraints? Maybe if you base your patch on top of the others in the series that implement the feature?

[MaskRay]

clang/docs/LanguageExtensions.rst

1273 ↗

(On Diff #240681)

Is the canonical spelling %l2?

[void]

In D73319#1843129, @nickdesaulniers wrote:

In D73319#1842951, @void wrote:

In D73319#1842900, @nickdesaulniers wrote:

Great idea; thanks for the patch! Needs documentation. :)

I can't find a place for documentation of extensions, at least not the names of extensions like gnu_asm.

How about https://clang.llvm.org/docs/LanguageExtensions.html#checks-for-standard-language-features ? Then we can add both gnu_asm and gnu_asm_goto_with_outputs.

That looks like it's features specific to various versions of C/C++. There were other examples like https://clang.llvm.org/docs/LanguageExtensions.html#blocks.

clang/test/Parser/asm-goto.c

9 ↗

(On Diff #240663)

There's one below in zoo. The order of these patches is a bit wonky because the front-end patch, which has more tests for AGWO, should go in before this one.

[void]

clang/docs/LanguageExtensions.rst

1273 ↗

(On Diff #240681)

Nice catch! I patched it in D69876.

[void]

I'm going to merge this into D69876 as it's closely related.

clang/include/clang/Basic/Features.def

 EXTENSION(cxx_binary_literals, true)
 EXTENSION(cxx_init_captures, LangOpts.CPlusPlus11)
 EXTENSION(cxx_variable_templates, LangOpts.CPlusPlus)
 // Miscellaneous language extensions
 EXTENSION(overloadable_unmarked, true)
 EXTENSION(pragma_clang_attribute_namespaces, true)
 EXTENSION(pragma_clang_attribute_external_declaration, true)
 EXTENSION(gnu_asm, LangOpts.GNUAsm)
+EXTENSION(gnu_asm_goto_with_outputs, true)
 
 #undef EXTENSION
 #undef FEATURE

clang/test/Parser/asm-goto-with-outputs.c

+// RUN: %clang_cc1 -triple i386-pc-linux-gnu -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -fsyntax-only -verify %s
+// expected-no-diagnostics
+
+#if !__has_extension(gnu_asm)
+#error Extension 'gnu_asm' should be available by default
+#endif
+#if !__has_extension(gnu_asm_goto_with_outputs)
+#error Extension 'gnu_asm_goto_with_outputs' should be available by default
+#endif
+
+int test1(int cond) {
+  asm volatile goto("testl %0, %0; jne %l2;" : "=r"(cond) : "r"(cond) :: label_true, loop);
+  asm volatile goto("testl %0, %0; jne %l3;" : "=r"(cond) : "r"(cond) :: label_true, loop);
+  return 0;
+loop:
+  return 0;
+label_true:
+  return 1;
+}
+
+int test2(int out1, int out2) {
+  asm volatile goto("testl %0, %0; jne %l3;" : "=r"(out1), "=r"(out2) : "r"(out1) :: label_true, loop);
+  asm volatile goto("testl %0, %0; jne %l4;" : "=r"(out1), "=r"(out2) : "r"(out1) :: label_true, loop);
+  return 0;
+loop:
+  return 0;
+label_true:
+  return 1;
+}
+
+int test3(int out1, int out2) {
+  if (out1 < out2)
+    asm volatile goto("jne %l3" : "+S"(out1), "+D"(out2) : "r"(out1) :: label_true, loop);
+  else
+    asm volatile goto("jne %l5" : "+S"(out1), "+D"(out2) : "r"(out1), "r"(out2) :: label_true, loop);
+  return out1 + out2;
+loop:
+  return -1;
+label_true:
+  return -2;
+}
+
+int test4(int addr, int size, int limit) {
+  asm goto(
+      "add %1,%0 ; "
+      "jc %l[t_err] ; "
+      "cmp %2,%0 ; "
+      "ja %l[t_err] ; "
+      : "+r" (addr)
+      : "g" (size), "g" (limit)
+      : : t_err);
+  return 0;
+t_err:
+  return 1;
+}
+
+int test5(int out1) {
+  int out2 = 42;
+  asm volatile goto("testl %0, %0; testl %1, %1; jne %l2" : "+S"(out2) : "r"(out1) :: label_true, landing);
+landing:
+  return out1 + out2;
+label_true:
+  return -2;
+}