[PAC][MC][AArch64] Fix error message for AUTH_ABS64 reloc with ILP32

[kovdan01]

The LP64 eqv: should say that the equivalent is AUTH_ABS64 rather than ABS64 when trying to emit an AUTH absolute reloc with ILP32.

[llvmbot]

@llvm/pr-subscribers-mc

@llvm/pr-subscribers-backend-aarch64

Author: Daniil Kovalev (kovdan01)

Changes

The LP64 eqv: should say that the equivalent is AUTH_ABS64 rather than ABS64 when trying to emit an AUTH absolute reloc with ILP32.

---

Full diff: https://github.com/llvm/llvm-project/pull/89563.diff

2 Files Affected:

• (modified) llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp (+8-8)
• (modified) llvm/test/MC/AArch64/ilp32-diagnostics.s (+8)

diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
index 6e074b6a63c41d..abbf20257edcc0 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
@@ -211,18 +211,18 @@ unsigned AArch64ELFObjectWriter::getRelocType(MCContext &Ctx,
               Target.getAccessVariant() == MCSymbolRefExpr::VK_GOTPCREL)
                  ? ELF::R_AARCH64_GOTPCREL32
                  : R_CLS(ABS32);
-    case FK_Data_8:
+    case FK_Data_8: {
+      bool IsAuth = (RefKind == AArch64MCExpr::VK_AUTH ||
+                     RefKind == AArch64MCExpr::VK_AUTHADDR);
       if (IsILP32) {
         Ctx.reportError(Fixup.getLoc(),
-                        "ILP32 8 byte absolute data "
-                        "relocation not supported (LP64 eqv: ABS64)");
+                        Twine("ILP32 8 byte absolute data "
+                              "relocation not supported (LP64 eqv: ") +
+                            (IsAuth ? "AUTH_ABS64" : "ABS64") + Twine(')'));
         return ELF::R_AARCH64_NONE;
-      } else {
-        if (RefKind == AArch64MCExpr::VK_AUTH ||
-            RefKind == AArch64MCExpr::VK_AUTHADDR)
-          return ELF::R_AARCH64_AUTH_ABS64;
-        return ELF::R_AARCH64_ABS64;
       }
+      return (IsAuth ? ELF::R_AARCH64_AUTH_ABS64 : ELF::R_AARCH64_ABS64);
+    }
     case AArch64::fixup_aarch64_add_imm12:
       if (RefKind == AArch64MCExpr::VK_DTPREL_HI12)
         return R_CLS(TLSLD_ADD_DTPREL_HI12);
diff --git a/llvm/test/MC/AArch64/ilp32-diagnostics.s b/llvm/test/MC/AArch64/ilp32-diagnostics.s
index 65c9e4ea5a1c56..4ca15f160418da 100644
--- a/llvm/test/MC/AArch64/ilp32-diagnostics.s
+++ b/llvm/test/MC/AArch64/ilp32-diagnostics.s
@@ -8,6 +8,14 @@
 
         .xword sym+16
 // CHECK-ERROR: error: ILP32 8 byte absolute data relocation not supported (LP64 eqv: ABS64)
+// CHECK-ERROR: ^
+
+        .xword sym@AUTH(da,42)
+// CHECK-ERROR: error: ILP32 8 byte absolute data relocation not supported (LP64 eqv: AUTH_ABS64)
+// CHECK-ERROR: ^
+
+        .xword sym@AUTH(da,42,addr)
+// CHECK-ERROR: error: ILP32 8 byte absolute data relocation not supported (LP64 eqv: AUTH_ABS64)
 // CHECK-ERROR: ^
 
         movz x7, #:abs_g3:some_label

[kovdan01]

AArch64ELFObjectWriter::getRelocType contains many else's after return. If nobody minds, I'll submit a subsequent PR removing use of else after return in this function.

[MaskRay]

8-byte absolute data relocation is not supported in ILP32?

[kovdan01]

According to the spec, it's not - see no "ELF32 code" for R_<CLS>_ABS64 in the table here https://github.com/ARM-software/abi-aa/blob/main/aaelf64/aaelf64.rst#static-data-relocations

[MaskRay]

Ok, I was suggesting a candidate diagnostic message

8-byte absolute data relocation is not supported in ILP32

[kovdan01]

It looks like that error messages across the function use some convention, so it's probably better to stick with it (or change the messages everywhere at once)