[Thumb] 32-bit encodings of 'cps' are not valid for v7M

[olista01]

Summary

v7M only allows the 16-bit encoding of the 'cps' (Change Processor State) instruction, and does not have the 32-bit encoding which is valid from v6T2 onwards.

[rengolin]

LGTM, Thanks!

--renato

[olista01]

Thanks, committed as r218382.

lib/Target/ARM/ARMInstrThumb2.td

 }
 
 
 // Change Processor State is a system instruction.
 // FIXME: Since the asm parser has currently no clean way to handle optional
 // operands, create 3 versions of the same instruction. Once there's a clean
 // framework to represent optional operands, change this behavior.
 class t2CPS<dag iops, string asm_op> : T2XI<(outs), iops, NoItinerary,
-            !strconcat("cps", asm_op), []> {
+            !strconcat("cps", asm_op), []>,
+          Requires<[IsThumb2, IsNotMClass]> {
   bits<2> imod;
   bits<3> iflags;
   bits<5> mode;
   bit M;
 
   let Inst{31-11} = 0b111100111010111110000;
   let Inst{10-9}  = imod;
   let Inst{8}     = M;

lib/Target/ARM/AsmParser/ARMAsmParser.cpp

Operands.push_back(ARMOperand::CreateCondCode(
                          ARMCC::CondCodes(PredicationCode), Loc));
   }
 
   // Add the processor imod operand, if necessary.
   if (ProcessorIMod) {
     Operands.push_back(ARMOperand::CreateImm(
           MCConstantExpr::Create(ProcessorIMod, getContext()),
                                  NameLoc, NameLoc));
+  } else if (Mnemonic == "cps" && isMClass()) {
+    return Error(NameLoc, "instruction 'cps' requires effect for M-class");
   }
 
   // Add the remaining tokens in the mnemonic.
   while (Next != StringRef::npos) {
     Start = Next;
     Next = Name.find('.', Start + 1);
     StringRef ExtraToken = Name.slice(Start, Next);
 

test/MC/ARM/cps.s

+@ RUN: llvm-mc -triple=thumbv6t2--none-eabi -show-encoding < %s | FileCheck %s
+@ RUN: llvm-mc -triple=thumbv7a--none-eabi -show-encoding < %s | FileCheck %s
+@ RUN: llvm-mc -triple=thumbv7r--none-eabi -show-encoding < %s | FileCheck %s
+@ RUN: llvm-mc -triple=thumbv8a--none-eabi -show-encoding < %s | FileCheck %s
+@ RUN: not llvm-mc -triple=thumbv7m--none-eabi -show-encoding < %s 2>&1 | FileCheck %s --check-prefix=UNDEF
+
+  cpsie f
+  cpsie i, #3
+  cps #0
+
+@ CHECK: cpsie f                         @ encoding: [0x61,0xb6]
+@ CHECK: cpsie   i, #3                   @ encoding: [0xaf,0xf3,0x43,0x85]
+@ CHECK: cps     #0                      @ encoding: [0xaf,0xf3,0x00,0x81]
+
+@ UNDEF-DAG: cpsie f                         @ encoding: [0x61,0xb6]
+@ UNDEF-DAG: error: instruction requires:
+@ UNDEF-DAG: error: instruction 'cps' requires effect for M-class