add new option -no-xcoff-visibility for llc

[DiggerLin]

Summary

when there is a -no-xcoff-visibility for llc ,
Not emit the visibility attribute for asm in AIX OS or give all symbols 'unspecified' visibility in xcoff object file

[DiggerLin]

according to https://reviews.llvm.org/D87451#inline-818669

merge the patch to https://reviews.llvm.org/D87451

llvm/include/llvm/CodeGen/CommandFlags.h

 bool getRelaxELFRelocations();
 
 bool getDataSections();
 Optional<bool> getExplicitDataSections();
 
 bool getFunctionSections();
 Optional<bool> getExplicitFunctionSections();
 
+bool getNoXCOFFVisibility();
+
 std::string getBBSections();
 
 unsigned getTLSSize();
 
 bool getEmulatedTLS();
 
 bool getUniqueSectionNames();
 

llvm/lib/CodeGen/CommandFlags.cpp

 CGOPT(bool, StackSymbolOrdering)
 CGOPT(unsigned, OverrideStackAlignment)
 CGOPT(bool, StackRealign)
 CGOPT(std::string, TrapFuncName)
 CGOPT(bool, UseCtors)
 CGOPT(bool, RelaxELFRelocations)
 CGOPT_EXP(bool, DataSections)
 CGOPT_EXP(bool, FunctionSections)
+CGOPT(bool, NoXCOFFVisibility)
 CGOPT(std::string, BBSections)
 CGOPT(unsigned, TLSSize)
 CGOPT(bool, EmulatedTLS)
 CGOPT(bool, UniqueSectionNames)
 CGOPT(bool, UniqueBasicBlockSectionNames)
 CGOPT(EABI, EABIVersion)
 CGOPT(DebuggerKind, DebuggerTuningOpt)
 CGOPT(bool, EnableStackSizeSection)
static cl::opt<bool> DataSections(
       cl::init(false));
   CGBINDOPT(DataSections);
 
   static cl::opt<bool> FunctionSections(
       "function-sections", cl::desc("Emit functions into separate sections"),
       cl::init(false));
   CGBINDOPT(FunctionSections);
 
+  static cl::opt<bool> NoXCOFFVisibility(
+      "no-xcoff-visibility",
+      cl::desc("Not emit the visibility attribute for asm in AIX OS or give "
+               "all symbols 'unspecified' visibility in xcoff object file"),
+      cl::init(false));
+  CGBINDOPT(NoXCOFFVisibility);
+
   static cl::opt<std::string> BBSections(
       "basic-block-sections",
       cl::desc("Emit basic blocks into separate sections"),
       cl::value_desc("all | <function list (file)> | labels | none"),
       cl::init("none"));
   CGBINDOPT(BBSections);
 
   static cl::opt<unsigned> TLSSize(
TargetOptions codegen::InitTargetOptionsFromCodeGenFlags() {
   Options.NoZerosInBSS = getDontPlaceZerosInBSS();
   Options.GuaranteedTailCallOpt = getEnableGuaranteedTailCallOpt();
   Options.StackAlignmentOverride = getOverrideStackAlignment();
   Options.StackSymbolOrdering = getStackSymbolOrdering();
   Options.UseInitArray = !getUseCtors();
   Options.RelaxELFRelocations = getRelaxELFRelocations();
   Options.DataSections = getDataSections();
   Options.FunctionSections = getFunctionSections();
+  Options.NoXCOFFVisibility = getNoXCOFFVisibility();
   Options.BBSections = getBBSectionsMode(Options);
   Options.UniqueSectionNames = getUniqueSectionNames();
   Options.UniqueBasicBlockSectionNames = getUniqueBasicBlockSectionNames();
   Options.TLSSize = getTLSSize();
   Options.EmulatedTLS = getEmulatedTLS();
   Options.ExplicitEmulatedTLS = EmulatedTLSView->getNumOccurrences() > 0;
   Options.ExceptionModel = getExceptionModel();
   Options.EmitStackSizeSection = getEnableStackSizeSection();

llvm/test/CodeGen/PowerPC/aix-no-xcoff-visibility.ll

+; RUN: llc -verify-machineinstrs -mtriple powerpc-ibm-aix-xcoff -mcpu=pwr4 \
+; RUN:     -mattr=-altivec  < %s | \
+; RUN:   FileCheck --check-prefix=VISIBILITY-ASM %s
+; RUN: llc -verify-machineinstrs -mtriple powerpc-ibm-aix-xcoff -mcpu=pwr4 \
+; RUN:     -mattr=-altivec -no-xcoff-visibility < %s | \
+; RUN:   FileCheck --check-prefix=NOVISIBILITY-ASM %s
+; RUN: llc -verify-machineinstrs -mtriple powerpc64-ibm-aix-xcoff -mcpu=pwr4 \
+; RUN:     -mattr=-altivec < %s | \
+; RUN:   FileCheck --check-prefix=VISIBILITY-ASM %s
+; RUN: llc -verify-machineinstrs -mtriple powerpc64-ibm-aix-xcoff -mcpu=pwr4 \
+; RUN:     -mattr=-altivec -no-xcoff-visibility < %s | \
+; RUN:   FileCheck --check-prefix=NOVISIBILITY-ASM %s
+
+@foo_p = global void ()* @zoo_extern_h, align 4
+@b = protected global i32 0, align 4
+
+define hidden void @foo_h(i32* %p) {
+entry:
+  %p.addr = alloca i32*, align 4
+  store i32* %p, i32** %p.addr, align 4
+  %0 = load i32*, i32** %p.addr, align 4
+  %1 = load i32, i32* %0, align 4
+  %inc = add nsw i32 %1, 1
+  store i32 %inc, i32* %0, align 4
+  ret void
+}
+
+declare hidden void @zoo_extern_h()
+
+define protected void @bar() {
+entry:
+  call void @foo_h(i32* @b)
+  %0 = load void ()*, void ()** @foo_p, align 4
+  call void %0()
+  ret void
+}
+
+; VISIBILITY-ASM: .globl  foo_h[DS],hidden
+; VISIBILITY-ASM: .globl  .foo_h,hidden
+; VISIBILITY-ASM: .globl  bar[DS],protected
+; VISIBILITY-ASM: .globl  .bar,protected
+; VISIBILITY-ASM: .globl  b,protected
+
+; NOVISIBILITY-ASM: .globl  foo_h[DS]
+; NOVISIBILITY-ASM: .globl  .foo_h
+; NOVISIBILITY-ASM: .globl  bar[DS]
+; NOVISIBILITY-ASM: .globl  .bar
+; NOVISIBILITY-ASM: .globl  b