[PowerPC] Support local-dynamic TLS relocation on AIX (#66316)

Supports TLS local-dynamic on AIX, generates below sequence of code:

```
.tc foo[TC],foo[TL]@ld # Variable offset, ld relocation specifier
.tc mh[TC],mh[TC]@ml # Module handle for the caller
lwz 3,mh[TC]\(2\) $$ For 64-bit: ld 3,mh[TC]\(2\)
bla .__tls_get_mod # Modifies r0,r3,r4,r5,r11,lr,cr0
#r3 = &TLS for module
lwz 4,foo[TC]\(2\) $$ For 64-bit: ld 4,foo[TC]\(2\)
add 5,3,4 # Compute &foo
.rename mh[TC], "\_$TLSML" # Symbol for the module handle must have the name "_$TLSML"
```

---------

Co-authored-by: tingwang <[email protected]>
Co-authored-by: tingwang <[email protected]>

Author: 3 people

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -693,7 +693,6 @@ def err_drv_cannot_mix_options : Error<"cannot specify '%1' along with '%0'">;
 def err_drv_invalid_object_mode : Error<
   "OBJECT_MODE setting %0 is not recognized and is not a valid setting">;
 
-def err_aix_unsupported_tls_model : Error<"TLS model '%0' is not yet supported on AIX">;
 def err_roptr_requires_data_sections: Error<"-mxcoff-roptr is supported only with -fdata-sections">;
 def err_roptr_cannot_build_shared: Error<"-mxcoff-roptr is not supported with -shared">;
 

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1975,14 +1975,6 @@ bool CompilerInvocation::ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args,
     Opts.LinkBitcodeFiles.push_back(F);
   }
 
-  if (Arg *A = Args.getLastArg(OPT_ftlsmodel_EQ)) {
-    if (T.isOSAIX()) {
-      StringRef Name = A->getValue();
-      if (Name == "local-dynamic")
-        Diags.Report(diag::err_aix_unsupported_tls_model) << Name;
-    }
-  }
-
   if (Arg *A = Args.getLastArg(OPT_fdenormal_fp_math_EQ)) {
     StringRef Val = A->getValue();
     Opts.FPDenormalMode = llvm::parseDenormalFPAttribute(Val);

clang/lib/Sema/SemaDeclAttr.cpp

@@ -2053,12 +2053,6 @@ static void handleTLSModelAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
     return;
   }
 
-  if (S.Context.getTargetInfo().getTriple().isOSAIX() &&
-      Model == "local-dynamic") {
-    S.Diag(LiteralLoc, diag::err_aix_attr_unsupported_tls_model) << Model;
-    return;
-  }
-
   D->addAttr(::new (S.Context) TLSModelAttr(S.Context, AL, Model));
 }
 

clang/test/CodeGen/PowerPC/aix-tls-model.cpp

@@ -1,11 +1,11 @@
 // RUN: %clang_cc1 %s -triple powerpc-unknown-aix -target-cpu pwr8 -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-GD
 // RUN: %clang_cc1 %s -triple powerpc-unknown-aix -target-cpu pwr8 -ftls-model=global-dynamic -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-GD
-// RUN: not %clang_cc1 %s -triple powerpc-unknown-aix -target-cpu pwr8 -ftls-model=local-dynamic -emit-llvm 2>&1 | FileCheck %s -check-prefix=CHECK-LD-ERROR
+// RUN: %clang_cc1 %s -triple powerpc-unknown-aix -target-cpu pwr8 -ftls-model=local-dynamic -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-LD
 // RUN: %clang_cc1 %s -triple powerpc-unknown-aix -target-cpu pwr8 -ftls-model=initial-exec -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-IE
 // RUN: %clang_cc1 %s -triple powerpc-unknown-aix -target-cpu pwr8 -ftls-model=local-exec -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-LE
 // RUN: %clang_cc1 %s -triple powerpc64-unknown-aix -target-cpu pwr8 -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-GD
 // RUN: %clang_cc1 %s -triple powerpc64-unknown-aix -target-cpu pwr8 -ftls-model=global-dynamic -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-GD
-// RUN: not %clang_cc1 %s -triple powerpc64-unknown-aix -target-cpu pwr8 -ftls-model=local-dynamic -emit-llvm 2>&1 | FileCheck %s -check-prefix=CHECK-LD-ERROR
+// RUN: %clang_cc1 %s -triple powerpc64-unknown-aix -target-cpu pwr8 -ftls-model=local-dynamic -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-LD
 // RUN: %clang_cc1 %s -triple powerpc64-unknown-aix -target-cpu pwr8 -ftls-model=initial-exec -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-IE
 // RUN: %clang_cc1 %s -triple powerpc64-unknown-aix -target-cpu pwr8 -ftls-model=local-exec -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-LE
 
@@ -21,7 +21,10 @@ int f() {
 // CHECK-GD: @z2 ={{.*}} global i32 0
 // CHECK-GD: @x ={{.*}} thread_local global i32 0
 // CHECK-GD: @_ZZ1fvE1y = internal thread_local global i32 0
-// CHECK-LD-ERROR:  error: TLS model 'local-dynamic' is not yet supported on AIX
+// CHECK-LD: @z1 ={{.*}} global i32 0
+// CHECK-LD: @z2 ={{.*}} global i32 0
+// CHECK-LD: @x ={{.*}} thread_local(localdynamic) global i32 0
+// CHECK-LD: @_ZZ1fvE1y = internal thread_local(localdynamic) global i32 0
 // CHECK-IE: @z1 ={{.*}} global i32 0
 // CHECK-IE: @z2 ={{.*}} global i32 0
 // CHECK-IE: @x ={{.*}} thread_local(initialexec) global i32 0

clang/test/Sema/aix-attr-tls_model.c

@@ -6,6 +6,6 @@
 #endif
 
 static __thread int y __attribute((tls_model("global-dynamic"))); // no-warning
-static __thread int y __attribute((tls_model("local-dynamic"))); // expected-error {{TLS model 'local-dynamic' is not yet supported on AIX}}
+static __thread int y __attribute((tls_model("local-dynamic"))); // expected-no-diagnostics
 static __thread int y __attribute((tls_model("initial-exec"))); // no-warning
 static __thread int y __attribute((tls_model("local-exec"))); // no-warning

llvm/include/llvm/MC/MCExpr.h

@@ -307,6 +307,8 @@ class MCSymbolRefExpr : public MCExpr {
     VK_PPC_AIX_TLSGDM,      // symbol@m
     VK_PPC_AIX_TLSIE,       // symbol@ie
     VK_PPC_AIX_TLSLE,       // symbol@le
+    VK_PPC_AIX_TLSLD,       // symbol@ld
+    VK_PPC_AIX_TLSML,       // symbol@ml
     VK_PPC_GOT_TLSLD,       // symbol@got@tlsld
     VK_PPC_GOT_TLSLD_LO,    // symbol@got@tlsld@l
     VK_PPC_GOT_TLSLD_HI,    // symbol@got@tlsld@h

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -2418,6 +2418,15 @@ MCSection *TargetLoweringObjectFileXCOFF::getSectionForExternalReference(
   SmallString<128> Name;
   getNameWithPrefix(Name, GO, TM);
 
+  // AIX TLS local-dynamic does not need the external reference for the
+  // "_$TLSML" symbol.
+  if (GO->getThreadLocalMode() == GlobalVariable::LocalDynamicTLSModel &&
+      GO->hasName() && GO->getName() == "_$TLSML") {
+    return getContext().getXCOFFSection(
+        Name, SectionKind::getData(),
+        XCOFF::CsectProperties(XCOFF::XMC_TC, XCOFF::XTY_SD));
+  }
+
   XCOFF::StorageMappingClass SMC =
       isa<Function>(GO) ? XCOFF::XMC_DS : XCOFF::XMC_UA;
   if (GO->isThreadLocal())
@@ -2675,13 +2684,17 @@ MCSection *TargetLoweringObjectFileXCOFF::getSectionForTOCEntry(
   // the chance of needing -bbigtoc is decreased. Also, the toc-entry for
   // EH info is never referenced directly using instructions so it can be
   // allocated with TE storage-mapping class.
+  // The "_$TLSML" symbol for TLS local-dynamic mode requires XMC_TC, otherwise
+  // the AIX assembler will complain.
   return getContext().getXCOFFSection(
       cast<MCSymbolXCOFF>(Sym)->getSymbolTableName(), SectionKind::getData(),
-      XCOFF::CsectProperties((TM.getCodeModel() == CodeModel::Large ||
-                              cast<MCSymbolXCOFF>(Sym)->isEHInfo())
-                                 ? XCOFF::XMC_TE
-                                 : XCOFF::XMC_TC,
-                             XCOFF::XTY_SD));
+      XCOFF::CsectProperties(
+          ((TM.getCodeModel() == CodeModel::Large &&
+            cast<MCSymbolXCOFF>(Sym)->getSymbolTableName() != "_$TLSML") ||
+           cast<MCSymbolXCOFF>(Sym)->isEHInfo())
+              ? XCOFF::XMC_TE
+              : XCOFF::XMC_TC,
+          XCOFF::XTY_SD));
 }
 
 MCSection *TargetLoweringObjectFileXCOFF::getSectionForLSDA(

llvm/lib/MC/MCExpr.cpp

@@ -338,6 +338,10 @@ StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
     return "ie";
   case VK_PPC_AIX_TLSLE:
     return "le";
+  case VK_PPC_AIX_TLSLD:
+    return "ld";
+  case VK_PPC_AIX_TLSML:
+    return "ml";
   case VK_PPC_GOT_TLSLD: return "got@tlsld";
   case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l";
   case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h";

llvm/lib/MC/XCOFFObjectWriter.cpp

@@ -715,7 +715,8 @@ void XCOFFObjectWriter::recordRelocation(MCAssembler &Asm,
   if (Type == XCOFF::RelocationType::R_POS ||
       Type == XCOFF::RelocationType::R_TLS ||
       Type == XCOFF::RelocationType::R_TLS_LE ||
-      Type == XCOFF::RelocationType::R_TLS_IE)
+      Type == XCOFF::RelocationType::R_TLS_IE ||
+      Type == XCOFF::RelocationType::R_TLS_LD)
     // The FixedValue should be symbol's virtual address in this object file
     // plus any constant value that we might get.
     FixedValue = getVirtualAddress(SymA, SymASec) + Target.getConstant();

llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp

@@ -231,12 +231,19 @@ class PPCTargetAsmStreamer : public PPCTargetStreamer {
       MCSymbolXCOFF *TCSym =
           cast<MCSectionXCOFF>(Streamer.getCurrentSectionOnly())
               ->getQualNameSymbol();
-      // On AIX, we have a region handle (symbol@m) and the variable offset
-      // (symbol@{gd|ie|le}) for TLS variables, depending on the TLS model.
+      // On AIX, we have TLS variable offsets (symbol@({gd|ie|le|ld}) depending
+      // on the TLS access method (or model). For the general-dynamic access
+      // method, we also have region handle (symbol@m) for each variable. For
+      // local-dynamic, there is a module handle (_$TLSML[TC]@ml) for all
+      // variables. Finally for local-exec and initial-exec, we have a thread
+      // pointer, in r13 for 64-bit mode and returned by .__get_tpointer for
+      // 32-bit mode.
       if (Kind == MCSymbolRefExpr::VariantKind::VK_PPC_AIX_TLSGD ||
           Kind == MCSymbolRefExpr::VariantKind::VK_PPC_AIX_TLSGDM ||
           Kind == MCSymbolRefExpr::VariantKind::VK_PPC_AIX_TLSIE ||
-          Kind == MCSymbolRefExpr::VariantKind::VK_PPC_AIX_TLSLE)
+          Kind == MCSymbolRefExpr::VariantKind::VK_PPC_AIX_TLSLE ||
+          Kind == MCSymbolRefExpr::VariantKind::VK_PPC_AIX_TLSLD ||
+          Kind == MCSymbolRefExpr::VariantKind::VK_PPC_AIX_TLSML)
         OS << "\t.tc " << TCSym->getName() << "," << XSym->getName() << "@"
            << MCSymbolRefExpr::getVariantKindName(Kind) << '\n';
       else