[llvm] r194512 - ARM: diagnose invalid system LDM/STM

[Tim Northover]

Author: tnorthover
Date: Tue Nov 12 15:32:41 2013
New Revision: 194512

URL: http://llvm.org/viewvc/llvm-project?rev=194512&view=rev
Log:
ARM: diagnose invalid system LDM/STM

The system LDM and STM instructions can't usually writeback to the base
register. The one exception is when an LDM is actually an exception-return
(i.e. contains PC in the register list).

(There's already a test that "ldm sp!, {r0-r3, pc}^" works, which is why there
is no positive test).

rdar://problem/15223374

Modified:
    llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
    llvm/trunk/test/MC/ARM/diagnostics.s

Modified: llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp?rev=194512&r1=194511&r2=194512&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp (original)
+++ llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp Tue Nov 12 15:32:41 2013
@@ -5481,6 +5481,22 @@ validateInstruction(MCInst &Inst,
                    "writeback register not allowed in register list");
     break;
   }
+  case ARM::sysLDMIA_UPD:
+  case ARM::sysLDMDA_UPD:
+  case ARM::sysLDMDB_UPD:
+  case ARM::sysLDMIB_UPD:
+    if (!listContainsReg(Inst, 3, ARM::PC))
+      return Error(Operands[4]->getStartLoc(),
+                   "writeback register only allowed on system LDM "
+                   "if PC in register-list");
+    break;
+  case ARM::sysSTMIA_UPD:
+  case ARM::sysSTMDA_UPD:
+  case ARM::sysSTMDB_UPD:
+  case ARM::sysSTMIB_UPD:
+    return Error(Operands[2]->getStartLoc(),
+                 "system STM cannot have writeback register");
+    break;
   case ARM::tMUL: {
     // The second source operand must be the same register as the destination
     // operand.

Modified: llvm/trunk/test/MC/ARM/diagnostics.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ARM/diagnostics.s?rev=194512&r1=194511&r2=194512&view=diff
==============================================================================
--- llvm/trunk/test/MC/ARM/diagnostics.s (original)
+++ llvm/trunk/test/MC/ARM/diagnostics.s Tue Nov 12 15:32:41 2013
@@ -460,3 +460,8 @@
 @ CHECK-ERRORS: error: instruction requires: FPARMv8
 @ CHECK-ERRORS: error: instruction requires: FPARMv8
 @ CHECK-ERRORS: error: instruction requires: FPARMv8
+
+        stm sp!, {r0, pc}^
+        ldm sp!, {r0}^
+@ CHECK-ERRORS: error: system STM cannot have writeback register
+@ CHECK-ERRORS: error: writeback register only allowed on system LDM if PC in register-list