[AArch64] ldr= pseudo-instruction silently ignored if register invalid

[olista01]

Summary

The AArch64 assembler was silently ignoring instructions like this:

ldr foo, =bar

AArch64AsmParser::parseOperand was returning true as the parse failed, but was not calling AArch64AsmParser::Error to report this to the user, so the instruction was ignored without printing an error message.

[t.p.northover]

Hi Oliver,

This looks good to me!

Tim.

lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

if (Mnemonic != "ldr") // only parse for ldr pseudo (e.g. ldr r0, =val)
       return Error(Loc, "unexpected token in operand");
     Parser.Lex(); // Eat '='
     const MCExpr *SubExprVal;
     if (getParser().parseExpression(SubExprVal))
       return true;
 
     if (Operands.size() < 2 ||
         !static_cast<AArch64Operand &>(*Operands[1]).isReg())
-      return true;
+      return Error(Loc, "Only valid when first operand is register");
 
     bool IsXReg =
         AArch64MCRegisterClasses[AArch64::GPR64allRegClassID].contains(
             Operands[1]->getReg());
 
     MCContext& Ctx = getContext();
     E = SMLoc::getFromPointer(Loc.getPointer() - 1);
     // If the op is an imm and can be fit into a mov, then replace ldr with mov.

test/MC/AArch64/ldr-pseudo-diagnostics.s

 //RUN: not llvm-mc -triple=aarch64-linux-gnu - < %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
 
 // simple test
 .section a, "ax", @progbits
 f1:
   ldr w0, =0x100000001
 // CHECK-ERROR: error: Immediate too large for register
 // CHECK-ERROR:   ldr w0, =0x100000001
 // CHECK-ERROR:           ^
 f2:
   ldr w0, =-0x80000001
 // CHECK-ERROR: error: Immediate too large for register
 // CHECK-ERROR:  ldr w0, =-0x80000001
 // CHECK-ERROR:          ^
+
+f3:
+  ldr foo, =1
+// CHECK-ERROR: error: Only valid when first operand is register
+// CHECK-ERROR:   ldr foo, =1
+// CHECK-ERROR:            ^
+
+f4:
+  add r0, r0, =1
+// CHECK-ERROR: error: unexpected token in operand
+// CHECK-ERROR:   add r0, r0, =1
+// CHECK-ERROR:               ^
+
+f5:
+  ldr x0, =())
+// CHECK-ERROR: error: unknown token in expression
+// CHECK-ERROR:   ldr x0, =())
+// CHECK-ERROR:             ^