AArch64: Reject label difference with a relocation specifier in generic assembler code

... instead of within AArch64ELFObjectWriter. Aligns with other targets.

Author: MaskRay

llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp

@@ -124,7 +124,7 @@ static bool evaluate(const MCSpecifierExpr &Expr, MCValue &Res,
   if (!Expr.getSubExpr()->evaluateAsRelocatable(Res, Asm))
     return false;
   Res.setSpecifier(Expr.getSpecifier());
-  return true;
+  return !Res.getSubSym();
 }
 
 AArch64MCAsmInfoDarwin::AArch64MCAsmInfoDarwin(bool IsILP32) {

llvm/test/MC/AArch64/error-location.s

@@ -22,7 +22,7 @@
 // CHECK: :[[@LINE+1]]:{{[0-9]+}}: error: 1-byte data relocations not supported
   .byte undef-.
 
-// CHECK: :[[@LINE+1]]:{{[0-9]+}}: error: Unsupported pc-relative fixup kind
+// CHECK: :[[@LINE+1]]:16: error: expected relocatable expression
   ldr x0, [x1, :lo12:undef-.]
 
 // CHECK: :[[@LINE+1]]:{{[0-9]+}}: error: invalid fixup for 8-bit load/store instruction

llvm/test/MC/AArch64/label-arithmetic-diags-elf.s

@@ -49,24 +49,14 @@ negative:
   // CHECK-NEXT: ^
 
   add w0, w1, #:lo12:external - end
-  // CHECK: :[[@LINE-1]]:{{[0-9]+}}: error: Unsupported pc-relative fixup kind
+  // CHECK: :[[@LINE-1]]:{{[0-9]+}}: error: expected relocatable expression
   // CHECK-NEXT: add w0, w1, #:lo12:external - end
-  // CHECK-NEXT: ^
 
   cmp w0, #:lo12:external - end
-  // CHECK: :[[@LINE-1]]:{{[0-9]+}}: error: Unsupported pc-relative fixup kind
-  // CHECK-NEXT: cmp w0, #:lo12:external - end
-  // CHECK-NEXT: ^
+  // CHECK: :[[@LINE-1]]:{{[0-9]+}}: error: expected relocatable expression
 
   add w0, w1, #:got_lo12:external - end
-  // CHECK: :[[@LINE-1]]:{{[0-9]+}}: error: Unsupported pc-relative fixup kind
-  // CHECK-NEXT: add w0, w1, #:got_lo12:external - end
-  // CHECK-NEXT: ^
-
-  cmp w0, #:got_lo12:external - end
-  // CHECK: :[[@LINE-1]]:{{[0-9]+}}: error: Unsupported pc-relative fixup kind
-  // CHECK-NEXT: cmp w0, #:got_lo12:external - end
-  // CHECK-NEXT: ^
+  // CHECK: :[[@LINE-1]]:{{[0-9]+}}: error: expected relocatable expression
 
   .section sec_y
 end_across_sec: