[CodeGen][test] XFAIL CodeGen/Generic/ForceStackAlign.ll on SPARC

[ro]

Summary

CodeGen/Generic/ForceStackAlign.ll FAILs on SPARC like this:

LLVM ERROR: Function "g" required stack re-alignment, but LLVM couldn't handle it (probably because it has a dynamic alloca).

According to the comments in llvm/lib/Target/Sparc/SparcFrameLowering.cpp (SparcFrameLowering::emitPrologue) and SparcRegisterInfo.cpp (SparcRegisterInfo::canRealignStack) this isn't going to change any time soon, so this patch XFAILs the test.

Tested on sparcv9-sun-solaris2.11.

[tejohnson]

Added @nickdesaulniers who authored D103048. Looking at the changes to this test in that patch, I'm wondering whether we should have an alternate version that forces the stack alignment the way it was done prior to that patch, to test that particular mechanism on Sparc?

[nickdesaulniers]

Was the llc flag -stack-alignment=32 previously being ignored on sparc?

[ro]

In D119119#3301984, @nickdesaulniers wrote:

Was the llc flag -stack-alignment=32 previously being ignored on sparc?

Seems so: I tried llc 12.0.0 and it silently ignores the option on SPARC.

llvm/test/CodeGen/Generic/ForceStackAlign.ll

 ; Check that stack alignment can be forced. Individual targets should test their
 ; specific implementation details.
 
 ; RUN: llc < %s -stackrealign | FileCheck %s
 ; CHECK-LABEL: @f
 ; CHECK-LABEL: @g
 
+; Stack realignment not supported.
+; XFAIL: sparc
+
 define i32 @f(i8* %p) nounwind {
 entry:
   %0 = load i8, i8* %p
   %conv = sext i8 %0 to i32
   ret i32 %conv
 }
 
 define i64 @g(i32 %i) nounwind {