[AArch64] Add support for SHF_AARCH64_PURECODE ELF section flag (1/3) (#125687)

Add support for the new SHF_AARCH64_PURECODE ELF section flag:
https://github.com/ARM-software/abi-aa/pull/304

The general implementation follows the existing one for ARM targets.
Generating object files with the `SHF_AARCH64_PURECODE` flag set is
enabled by the `+execute-only` target feature.

Related PRs:
* Clang: https://github.com/llvm/llvm-project/pull/125688
* LLD: https://github.com/llvm/llvm-project/pull/125689

1 files changed, 10 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 9f44f8b..be2f5fb 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -547,7 +547,7 @@ static unsigned getELFSectionType(StringRef Name, SectionKind K) {
   return ELF::SHT_PROGBITS;
 }
 
-static unsigned getELFSectionFlags(SectionKind K) {
+static unsigned getELFSectionFlags(SectionKind K, const Triple &T) {
   unsigned Flags = 0;
 
   if (!K.isMetadata() && !K.isExclude())
@@ -559,8 +559,12 @@ static unsigned getELFSectionFlags(SectionKind K) {
   if (K.isText())
     Flags |= ELF::SHF_EXECINSTR;
 
-  if (K.isExecuteOnly())
-    Flags |= ELF::SHF_ARM_PURECODE;
+  if (K.isExecuteOnly()) {
+    if (T.isAArch64())
+      Flags |= ELF::SHF_AARCH64_PURECODE;
+    else if (T.isARM() || T.isThumb())
+      Flags |= ELF::SHF_ARM_PURECODE;
+  }
 
   if (K.isWriteable())
     Flags |= ELF::SHF_WRITE;
@@ -845,7 +849,7 @@ static MCSection *selectExplicitSectionGlobal(const GlobalObject *GO,
   // Infer section flags from the section name if we can.
   Kind = getELFKindForNamedSection(SectionName, Kind);
 
-  unsigned Flags = getELFSectionFlags(Kind);
+  unsigned Flags = getELFSectionFlags(Kind, TM.getTargetTriple());
   auto [Group, IsComdat, ExtraFlags] = getGlobalObjectInfo(GO, TM);
   Flags |= ExtraFlags;
 
@@ -952,7 +956,7 @@ static MCSection *selectELFSectionForGlobal(
 
 MCSection *TargetLoweringObjectFileELF::SelectSectionForGlobal(
     const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
-  unsigned Flags = getELFSectionFlags(Kind);
+  unsigned Flags = getELFSectionFlags(Kind, TM.getTargetTriple());
 
   // If we have -ffunction-section or -fdata-section then we should emit the
   // global value to a uniqued section specifically for it.
@@ -972,7 +976,7 @@ MCSection *TargetLoweringObjectFileELF::SelectSectionForGlobal(
 MCSection *TargetLoweringObjectFileELF::getUniqueSectionForFunction(
     const Function &F, const TargetMachine &TM) const {
   SectionKind Kind = SectionKind::getText();
-  unsigned Flags = getELFSectionFlags(Kind);
+  unsigned Flags = getELFSectionFlags(Kind, TM.getTargetTriple());
   // If the function's section names is pre-determined via pragma or a
   // section attribute, call selectExplicitSectionGlobal.
   if (F.hasSection())