[XCOFF][AIX] Fix getSymbol to return the correct qualname when necessary

Summary:
AIX symbol have qualname and unqualified name. The stock getSymbol
could only return unqualified name, which leads us to patch many
caller side(lowerConstant, getMCSymbolForTOCPseudoMO).
So we should try to address this problem in the callee
side(getSymbol) and clean up the caller side instead.

Note: this is a "mostly" NFC patch, with a fix for the original
lowerConstant behavior.

Differential Revision: https://reviews.llvm.org/D78045

1 files changed, 34 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index a5f3801..8ed3e86 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -1966,6 +1966,40 @@ MCSection *TargetLoweringObjectFileWasm::getStaticDtorSection(
 //===----------------------------------------------------------------------===//
 //                                  XCOFF
 //===----------------------------------------------------------------------===//
+MCSymbol *
+TargetLoweringObjectFileXCOFF::getTargetSymbol(const GlobalValue *GV,
+                                               const TargetMachine &TM) const {
+  if (TM.getDataSections())
+    report_fatal_error("XCOFF unique data sections not yet implemented");
+
+  // We always use a qualname symbol for a GV that represents
+  // a declaration, a function descriptor, or a common symbol.
+  // It is inherently ambiguous when the GO represents the address of a
+  // function, as the GO could either represent a function descriptor or a
+  // function entry point. We choose to always return a function descriptor
+  // here.
+  if (const GlobalObject *GO = dyn_cast<GlobalObject>(GV)) {
+    if (GO->isDeclaration())
+      return cast<MCSectionXCOFF>(getSectionForExternalReference(GO, TM))
+          ->getQualNameSymbol();
+
+    SectionKind GOKind = getKindForGlobal(GO, TM);
+    if (GOKind.isText())
+      return cast<MCSectionXCOFF>(
+                 getSectionForFunctionDescriptor(cast<Function>(GO), TM))
+          ->getQualNameSymbol();
+    if (GOKind.isCommon() || GOKind.isBSSLocal())
+      return cast<MCSectionXCOFF>(SectionForGlobal(GO, GOKind, TM))
+          ->getQualNameSymbol();
+  }
+
+  // For all other cases, fall back to getSymbol to return the unqualified name.
+  // This could change for a GV that is a GlobalVariable when we decide to
+  // support -fdata-sections since we could avoid having label symbols if the
+  // linkage name is applied to the csect symbol.
+  return nullptr;
+}
+
 MCSection *TargetLoweringObjectFileXCOFF::getExplicitSectionGlobal(
     const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
   report_fatal_error("XCOFF explicit sections not yet implemented.");