[AIX] XFAIL CodeGen/Generic/externally_available.ll

[jsji]

Summary

Globals with “available_externally” linkage should never be emitted into the
object file corresponding to the LLVM module.

However, AIX system assembler default print error for undefined reference .
so AIX chose to emit the available externally symbols into .s,
so that users won't run into errors in situations like:

clang -target powerpc-ibm-aix -xc -<<<$'extern inline
__attribute__((__gnu_inline__)) void foo() {}\nvoid bar() { foo(); }' -O
-Xclang -disable-llvm-passes

[hubert.reinterpretcast]

It is not acceptable on AIX to emit references to symbols without declaring them unless if using as -u, which is less desirable than if the -u is not needed.

After:

$ clang -target powerpc-ibm-aix -xc -<<<$'extern inline __attribute__((__gnu_inline__)) void foo() {}\nvoid bar() { foo(); }' -O -Xclang -disable-llvm-passes -S -o - | grep -F foo
        bl .foo

Before:

bl .foo
.extern .foo
.extern foo[DS]

[jsji]

XFAIL the tests with comments.

[jsji]

In D102377#2755720, @hubert.reinterpretcast wrote:

It is not acceptable on AIX to emit references to symbols without declaring them unless if using as -u, which is less desirable than if the -u is not needed.

Thanks for the background, given that this was done intentionally, mark the test XFAIL on AIX with comments.

[hubert.reinterpretcast]

I think emitting only as a symbol table entry of a locally-undefined symbol is fine here. LGTM; thanks!

llvm/test/CodeGen/Generic/externally_available.ll

 ; RUN: llc -verify-machine-dom-info < %s | not grep test_
 
+; XFAIL: aix
+; AIX system assembler default print error for undefined reference .
+; so AIX chose to emit the available externally symbols into .s,
+; so that users won't run into errors in situations like:
+; clang -target powerpc-ibm-aix -xc -<<<$'extern inline __attribute__((__gnu_inline__)) void foo() {}\nvoid bar() { foo(); }' -O -Xclang -disable-llvm-passes
+
 ; test_function should not be emitted to the .s file.
 define available_externally i32 @test_function() {
   ret i32 4
 }
 
 ; test_global should not be emitted to the .s file.
 @test_global = available_externally global i32 4