[PowerPC] Support -fpatchable-function-entry (#92997)

For now only PPC big endian Linux 32 and 64 bit are supported.

PPC little endian Linux has XRAY support for 64-bit.
PPC AIX has different patchable function entry implementations.

Fixes #63220
Fixes #57031

Author: Chen Zheng

clang/include/clang/Basic/Attr.td

@@ -902,7 +902,7 @@ def PatchableFunctionEntry
     : InheritableAttr,
       TargetSpecificAttr<TargetArch<
           ["aarch64", "aarch64_be", "loongarch32", "loongarch64", "riscv32",
-           "riscv64", "x86", "x86_64"]>> {
+           "riscv64", "x86", "x86_64", "ppc", "ppc64"]>> {
   let Spellings = [GCC<"patchable_function_entry">];
   let Subjects = SubjectList<[Function, ObjCMethod]>;
   let Args = [UnsignedArgument<"Count">, DefaultIntArgument<"Offset", 0>];

clang/include/clang/Basic/AttrDocs.td

@@ -5800,7 +5800,8 @@ takes precedence over the command line option ``-fpatchable-function-entry=N,M``
 ``M`` defaults to 0 if omitted.
 
 This attribute is only supported on
-aarch64/aarch64-be/loongarch32/loongarch64/riscv32/riscv64/i386/x86-64 targets.
+aarch64/aarch64-be/loongarch32/loongarch64/riscv32/riscv64/i386/x86-64/ppc/ppc64 targets.
+For ppc/ppc64 targets, AIX is still not supported.
 }];
 }
 

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -3492,7 +3492,7 @@ def err_attr_tlsmodel_arg : Error<"tls_model must be \"global-dynamic\", "
 
 def err_attr_codemodel_arg : Error<"code model '%0' is not supported on this target">;
 
-def err_aix_attr_unsupported_tls_model : Error<"TLS model '%0' is not yet supported on AIX">;
+def err_aix_attr_unsupported : Error<"%0 attribute is not yet supported on AIX">;
 
 def err_tls_var_aligned_over_maximum : Error<
   "alignment (%0) of thread-local variable %1 is greater than the maximum supported "

clang/lib/Driver/ToolChains/Clang.cpp

@@ -6666,7 +6666,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     StringRef S0 = A->getValue(), S = S0;
     unsigned Size, Offset = 0;
     if (!Triple.isAArch64() && !Triple.isLoongArch() && !Triple.isRISCV() &&
-        !Triple.isX86())
+        !Triple.isX86() &&
+        !(!Triple.isOSAIX() && (Triple.getArch() == llvm::Triple::ppc ||
+                                Triple.getArch() == llvm::Triple::ppc64)))
       D.Diag(diag::err_drv_unsupported_opt_for_target)
           << A->getAsString(Args) << TripleStr;
     else if (S.consumeInteger(10, Size) ||

clang/lib/Sema/SemaDeclAttr.cpp

@@ -5247,6 +5247,10 @@ static void handleXRayLogArgsAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
 
 static void handlePatchableFunctionEntryAttr(Sema &S, Decl *D,
                                              const ParsedAttr &AL) {
+  if (S.Context.getTargetInfo().getTriple().isOSAIX()) {
+    S.Diag(AL.getLoc(), diag::err_aix_attr_unsupported) << AL;
+    return;
+  }
   uint32_t Count = 0, Offset = 0;
   if (!S.checkUInt32Argument(AL, AL.getArgAsExpr(0), Count, 0, true))
     return;

clang/test/Driver/fpatchable-function-entry.c

@@ -6,15 +6,20 @@
 // RUN: %clang --target=loongarch64 %s -fpatchable-function-entry=1,0 -c -### 2>&1 | FileCheck %s
 // RUN: %clang --target=riscv32 %s -fpatchable-function-entry=1,0 -c -### 2>&1 | FileCheck %s
 // RUN: %clang --target=riscv64 %s -fpatchable-function-entry=1,0 -c -### 2>&1 | FileCheck %s
+// RUN: %clang --target=powerpc-unknown-linux-gnu %s -fpatchable-function-entry=1,0 -c -### 2>&1 | FileCheck %s
+// RUN: %clang --target=powerpc64-unknown-linux-gnu %s -fpatchable-function-entry=1,0 -c -### 2>&1 | FileCheck %s
 // CHECK: "-fpatchable-function-entry=1"
 
 // RUN: %clang --target=aarch64 -fsyntax-only %s -fpatchable-function-entry=1,1 -c -### 2>&1 | FileCheck --check-prefix=11 %s
 // 11: "-fpatchable-function-entry=1" "-fpatchable-function-entry-offset=1"
 // RUN: %clang --target=aarch64 -fsyntax-only %s -fpatchable-function-entry=2,1 -c -### 2>&1 | FileCheck --check-prefix=21 %s
 // 21: "-fpatchable-function-entry=2" "-fpatchable-function-entry-offset=1"
 
-// RUN: not %clang --target=ppc64 -fsyntax-only %s -fpatchable-function-entry=1 2>&1 | FileCheck --check-prefix=TARGET %s
-// TARGET: error: unsupported option '-fpatchable-function-entry=1' for target 'ppc64'
+// RUN: not %clang --target=powerpc64-ibm-aix-xcoff -fsyntax-only %s -fpatchable-function-entry=1 2>&1 | FileCheck --check-prefix=AIX64 %s
+// AIX64: error: unsupported option '-fpatchable-function-entry=1' for target 'powerpc64-ibm-aix-xcoff'
+
+// RUN: not %clang --target=powerpc-ibm-aix-xcoff -fsyntax-only %s -fpatchable-function-entry=1 2>&1 | FileCheck --check-prefix=AIX32 %s
+// AIX32: error: unsupported option '-fpatchable-function-entry=1' for target 'powerpc-ibm-aix-xcoff'
 
 // RUN: not %clang --target=x86_64 -fsyntax-only %s -fpatchable-function-entry=1,0, 2>&1 | FileCheck --check-prefix=EXCESS %s
 // EXCESS: error: invalid argument '1,0,' to -fpatchable-function-entry=

clang/test/Sema/patchable-function-entry-attr.cpp

@@ -6,9 +6,14 @@
 // RUN: %clang_cc1 -triple loongarch64 -fsyntax-only -verify=silence %s
 // RUN: %clang_cc1 -triple riscv32 -fsyntax-only -verify=silence %s
 // RUN: %clang_cc1 -triple riscv64 -fsyntax-only -verify=silence %s
+// RUN: %clang_cc1 -triple powerpc-unknown-linux-gnu -fsyntax-only -verify=silence %s
+// RUN: %clang_cc1 -triple powerpc64-unknown-linux-gnu -fsyntax-only -verify=silence %s
 // RUN: %clang_cc1 -triple ppc64le -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix-xcoff -fsyntax-only -verify=AIX %s
+// RUN: %clang_cc1 -triple powerpc-ibm-aix-xcoff -fsyntax-only -verify=AIX %s
 
 // silence-no-diagnostics
 
+// AIX-error@+2 {{'patchable_function_entry' attribute is not yet supported on AIX}}
 // expected-warning@+1 {{unknown attribute 'patchable_function_entry' ignored}}
 [[gnu::patchable_function_entry(0)]] void f();

llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp

@@ -909,6 +909,23 @@ void PPCAsmPrinter::emitInstruction(const MachineInstr *MI) {
   // Lower multi-instruction pseudo operations.
   switch (MI->getOpcode()) {
   default: break;
+  case TargetOpcode::PATCHABLE_FUNCTION_ENTER: {
+    assert(!Subtarget->isAIXABI() &&
+           "AIX does not support patchable function entry!");
+    // PATCHABLE_FUNCTION_ENTER on little endian is for XRAY support which is
+    // handled in PPCLinuxAsmPrinter.
+    if (MAI->isLittleEndian())
+      return;
+    const Function &F = MF->getFunction();
+    unsigned Num = 0;
+    (void)F.getFnAttribute("patchable-function-entry")
+        .getValueAsString()
+        .getAsInteger(10, Num);
+    if (!Num)
+      return;
+    emitNops(Num);
+    return;
+  }
   case TargetOpcode::DBG_VALUE:
     llvm_unreachable("Should be handled target independently");
   case TargetOpcode::STACKMAP:
@@ -1780,7 +1797,7 @@ void PPCLinuxAsmPrinter::emitInstruction(const MachineInstr *MI) {
 
   switch (MI->getOpcode()) {
   default:
-    return PPCAsmPrinter::emitInstruction(MI);
+    break;
   case TargetOpcode::PATCHABLE_FUNCTION_ENTER: {
     // .begin:
     //   b .end # lis 0, FuncId[16..32]
@@ -1793,6 +1810,9 @@ void PPCLinuxAsmPrinter::emitInstruction(const MachineInstr *MI) {
     //
     // Update compiler-rt/lib/xray/xray_powerpc64.cc accordingly when number
     // of instructions change.
+    // XRAY is only supported on PPC Linux little endian.
+    if (!MAI->isLittleEndian())
+      break;
     MCSymbol *BeginOfSled = OutContext.createTempSymbol();
     MCSymbol *EndOfSled = OutContext.createTempSymbol();
     OutStreamer->emitLabel(BeginOfSled);
@@ -1909,6 +1929,7 @@ void PPCLinuxAsmPrinter::emitInstruction(const MachineInstr *MI) {
     llvm_unreachable("Tail call is handled in the normal case. See comments "
                      "around this assert.");
   }
+  return PPCAsmPrinter::emitInstruction(MI);
 }
 
 void PPCLinuxAsmPrinter::emitStartOfAsmFile(Module &M) {

llvm/test/CodeGen/PowerPC/patchable-function-entry.ll

@@ -0,0 +1,58 @@
+; RUN: llc -mtriple=powerpc %s -o - | FileCheck %s --check-prefixes=CHECK,PPC32
+; RUN: llc -mtriple=powerpc64 %s -o - | FileCheck %s --check-prefixes=CHECK,PPC64
+
+@a = global i32 0, align 4
+
+define void @f0() {
+; CHECK-LABEL: f0:
+; CHECK-NOT:   nop
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    blr
+; CHECK-NOT:   .section    __patchable_function_entries
+  ret void
+}
+
+define void @f1() "patchable-function-entry"="0" {
+; CHECK-LABEL: f1:
+; CHECK-NOT:   nop
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    blr
+; CHECK-NOT:   .section    __patchable_function_entries
+  ret void
+}
+
+define void @f2() "patchable-function-entry"="1" {
+; CHECK-LABEL: f2:
+; CHECK-LABEL-NEXT:  .Lfunc_begin2:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    nop
+; CHECK-NEXT:    blr
+; CHECK:       .section    __patchable_function_entries
+; PPC32:       .p2align    2, 0x0
+; PPC64:       .p2align    3, 0x0
+; PPC32-NEXT:  .long   .Lfunc_begin2
+; PPC64-NEXT:  .quad   .Lfunc_begin2
+  ret void
+}
+
+define i32 @f3() "patchable-function-entry"="1" "patchable-function-prefix"="2" {
+; CHECK-LABEL: .Ltmp0:
+; CHECK-COUNT-2: nop
+; CHECK-LABEL: f3:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    nop
+; PPC32:         lis 3, a@ha
+; PPC32-NEXT:    lwz 3, a@l(3)
+; PPC64:         addis 3, 2, .LC0@toc@ha
+; PPC64-NEXT:    ld 3, .LC0@toc@l(3)
+; PPC64-NEXT:    lwz 3, 0(3)
+; CHECK:         blr
+; CHECK:       .section    __patchable_function_entries
+; PPC32:       .p2align    2, 0x0
+; PPC64:       .p2align    3, 0x0
+; PPC32-NEXT:  .long   .Ltmp0
+; PPC64-NEXT:  .quad   .Ltmp0
+entry:
+  %0 = load i32, ptr @a, align 4
+  ret i32 %0
+}