AArch64: Relax restriction on discriminator when PAuth ifunc used.

llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp

@@ -220,7 +220,7 @@ class AArch64AsmPrinter : public AsmPrinter {
   void LowerLOADgotAUTH(const MachineInstr &MI);
 
   const MCExpr *emitPAuthRelocationAsIRelative(
-      const MCExpr *Target, uint16_t Disc, AArch64PACKey::ID KeyID,
+      const MCExpr *Target, uint64_t Disc, AArch64PACKey::ID KeyID,
       bool HasAddressDiversity, bool IsDSOLocal, const MCExpr *DSExpr);
 
   /// tblgen'erated driver function for lowering simple MI->MC
@@ -2461,7 +2461,7 @@ static bool targetSupportsIRelativeRelocation(const Triple &TT) {
 // ret
 // .popsection
 const MCExpr *AArch64AsmPrinter::emitPAuthRelocationAsIRelative(
-    const MCExpr *Target, uint16_t Disc, AArch64PACKey::ID KeyID,
+    const MCExpr *Target, uint64_t Disc, AArch64PACKey::ID KeyID,
     bool HasAddressDiversity, bool IsDSOLocal, const MCExpr *DSExpr) {
   const Triple &TT = TM.getTargetTriple();
 
@@ -2508,12 +2508,16 @@ const MCExpr *AArch64AsmPrinter::emitPAuthRelocationAsIRelative(
   if (HasAddressDiversity) {
     auto *PlacePlusDisc = MCBinaryExpr::createAdd(
         MCSymbolRefExpr::create(Place, OutStreamer->getContext()),
-        MCConstantExpr::create(static_cast<int16_t>(Disc),
-                               OutStreamer->getContext()),
+        MCConstantExpr::create(Disc, OutStreamer->getContext()),
         OutStreamer->getContext());
     emitAddress(*OutStreamer, AArch64::X1, PlacePlusDisc, /*IsDSOLocal=*/true,
                 *STI);
   } else {
+    if (!isUInt<16>(Disc)) {
+      OutContext.reportError(SMLoc(), "AArch64 PAC Discriminator '" +
+                                          Twine(Disc) +
+                                          "' out of range [0, 0xFFFF]");
+    }
     emitMOVZ(AArch64::X1, Disc, 0);
   }
 
@@ -2592,18 +2596,19 @@ AArch64AsmPrinter::lowerConstantPtrAuth(const ConstantPtrAuth &CPA) {
   }
 
   uint64_t Disc = CPA.getDiscriminator()->getZExtValue();
-  if (!isUInt<16>(Disc)) {
-    CPA.getContext().emitError("AArch64 PAC Discriminator '" + Twine(Disc) +
-                               "' out of range [0, 0xFFFF]");
-    Disc = 0;
-  }
 
   // Check if we need to represent this with an IRELATIVE and emit it if so.
   if (auto *IFuncSym = emitPAuthRelocationAsIRelative(
           Sym, Disc, AArch64PACKey::ID(KeyID), CPA.hasAddressDiscriminator(),
           BaseGVB && BaseGVB->isDSOLocal(), DSExpr))
     return IFuncSym;
 
+  if (!isUInt<16>(Disc)) {
+    CPA.getContext().emitError("AArch64 PAC Discriminator '" + Twine(Disc) +
+                               "' out of range [0, 0xFFFF]");
+    Disc = 0;
+  }
+
   if (DSExpr)
     report_fatal_error("deactivation symbols unsupported in constant "
                        "expressions on this target");

llvm/test/CodeGen/AArch64/ptrauth-irelative.ll

@@ -67,6 +67,19 @@
 ; CHECK-NEXT: .xword [[FUNC]]@FUNCINIT
 @disc = constant ptr ptrauth (ptr @dsolocal, i32 2, i64 0, ptr @disc), align 8
 
+; CHECK: disc65536:
+; CHECK-NEXT: [[PLACE:.*]]:
+; CHECK-NEXT: .section .text.startup
+; CHECK-NEXT: [[FUNC:.*]]:
+; CHECK-NEXT: adrp x0, dsolocal
+; CHECK-NEXT: add x0, x0, :lo12:dsolocal
+; CHECK-NEXT: adrp x1, [[PLACE]]+65536
+; CHECK-NEXT: add x1, x1, :lo12:[[PLACE]]+65536
+; CHECK-NEXT: b __emupac_pacda
+; CHECK-NEXT: .section .rodata
+; CHECK-NEXT: .xword [[FUNC]]@FUNCINIT
+@disc65536 = constant ptr ptrauth (ptr @dsolocal, i32 2, i64 65536, ptr @disc), align 8
+
 @global = external global i8
 
 ; CHECK: globalref:

llvm/test/CodeGen/AArch64/ptrauth-reloc.ll

@@ -175,3 +175,20 @@
 
 @g = external global i32
 @g.ref.ia.65536 = constant ptr ptrauth (ptr @g, i32 0, i64 65536)
+
+;--- err-disc-elf.ll
+
+; RUN: not llc < err-disc-elf.ll -mtriple aarch64-elf -mattr=+pauth 2>&1 \
+; RUN:   | FileCheck %s --check-prefix=CHECK-ERR-DISC-ELF
+; RUN: not llc < err-disc-elf.ll -mtriple aarch64-elf -mattr=+pauth \
+; RUN:   -global-isel -verify-machineinstrs -global-isel-abort=1 2>&1 \
+; RUN:   | FileCheck %s --check-prefix=CHECK-ERR-DISC-ELF
+
+@g = external global i32
+
+@ds = external global i8
+; CHECK-ERR-DISC-ELF-NOT: error: AArch64 PAC Discriminator '65537' out of range [0, 0xFFFF]
+@g.ref.da.65537 = constant ptr ptrauth (ptr @g, i32 2, i64 65537, ptr @g.ref.da.65537, ptr @ds)
+
+; CHECK-ERR-DISC-ELF: error: AArch64 PAC Discriminator '65538' out of range [0, 0xFFFF]
+@g.ref.da.65538 = constant ptr ptrauth (ptr @g, i32 2, i64 65538, ptr null, ptr @ds)