[llvm-branch-commits] [llvm] [AArch64] Only create called thunks when hardening against SLS (PR #97472)

[Kristof Beyls via llvm-branch-commits]

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@@ -36,38 +32,43 @@ using namespace llvm;
 
 #define AARCH64_SLS_HARDENING_NAME "AArch64 sls hardening pass"
 
+static const char SLSBLRNamePrefix[] = "__llvm_slsblr_thunk_";
+
 namespace {
 
-class AArch64SLSHardening : public MachineFunctionPass {
-public:
-  const TargetInstrInfo *TII;
-  const TargetRegisterInfo *TRI;
-  const AArch64Subtarget *ST;
+// Set of inserted thunks: bitmask with bits corresponding to
+// indexes in SLSBLRThunks array.
+typedef uint32_t ThunksSet;
 
-  static char ID;
-
-  AArch64SLSHardening() : MachineFunctionPass(ID) {
-    initializeAArch64SLSHardeningPass(*PassRegistry::getPassRegistry());
+struct SLSBLRThunkInserter : ThunkInserter<SLSBLRThunkInserter, ThunksSet> {
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kbeyls wrote:

I'm not sure if `SLSBLRThunkInserter` is the most appropriate name for this class.
IIUC, this class will also harden Returns and BRs, (see method `hardenReturnsAndBRs`), which does not insert thunks.
If I understand this correctly, I think sticking with the original name of "AArch64SLSHardening" describes better what this class does?

https://github.com/llvm/llvm-project/pull/97472