[ARM][Thumb2] Fix ADD/SUB invalid writes to SP

Summary:
This patch fixes pr23772  [ARM] r226200 can emit illegal thumb2 instruction: "sub sp, r12, #80".
The violation was that SUB and ADD (reg, immediate) instructions can only write to SP if the source register is also SP. So the above instructions was unpredictable.
To enforce that the instruction t2(ADD|SUB)ri does not write to SP we now enforce the destination register to be rGPR (That exclude PC and SP).
Different than the ARM specification, that defines one instruction that can read from SP, and one that can't, here we inserted one that can't write to SP, and other that can only write to SP as to reuse most of the hard-coded size optimizations.
When performing this change, it uncovered that emitting Thumb2 Reg plus Immediate could not emit all variants of ADD SP, SP #imm instructions before so it was refactored to be able to. (see test/CodeGen/Thumb2/mve-stacksplot.mir where we use a subw sp, sp, Imm12 variant )
It also uncovered a disassembly issue of adr.w instructions, that were only written as SUBW instructions (see llvm/test/MC/Disassembler/ARM/thumb2.txt).

Reviewers: eli.friedman, dmgreen, carwil, olista01, efriedma

Reviewed By: efriedma

Subscribers: john.brawn, efriedma, ostannard, kristof.beyls, hiraditya, dmgreen, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70680

llvm/lib/Target/ARM/ARMAsmPrinter.cpp

@@ -1171,11 +1171,15 @@ void ARMAsmPrinter::EmitUnwindingInstruction(const MachineInstr *MI) {
       case ARM::ADDri:
       case ARM::t2ADDri:
       case ARM::t2ADDri12:
+      case ARM::t2ADDspImm:
+      case ARM::t2ADDspImm12:
         Offset = -MI->getOperand(2).getImm();
         break;
       case ARM::SUBri:
       case ARM::t2SUBri:
       case ARM::t2SUBri12:
+      case ARM::t2SUBspImm:
+      case ARM::t2SUBspImm12:
         Offset = MI->getOperand(2).getImm();
         break;
       case ARM::tSUBspi:

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

@@ -3257,22 +3257,26 @@ bool ARMBaseInstrInfo::FoldImmediate(MachineInstr &UseMI, MachineInstr &DefMI,
       }
       break;
     case ARM::t2ADDrr:
-    case ARM::t2SUBrr:
+    case ARM::t2SUBrr: {
       if (UseOpc == ARM::t2SUBrr && Commute)
         return false;
 
       // ADD/SUB are special because they're essentially the same operation, so
       // we can handle a larger range of immediates.
+      const bool ToSP = DefMI.getOperand(0).getReg() == ARM::SP;
+      const unsigned t2ADD = ToSP ? ARM::t2ADDspImm : ARM::t2ADDri;
+      const unsigned t2SUB = ToSP ? ARM::t2SUBspImm : ARM::t2SUBri;
       if (ARM_AM::isT2SOImmTwoPartVal(ImmVal))
-        NewUseOpc = UseOpc == ARM::t2ADDrr ? ARM::t2ADDri : ARM::t2SUBri;
+        NewUseOpc = UseOpc == ARM::t2ADDrr ? t2ADD : t2SUB;
       else if (ARM_AM::isT2SOImmTwoPartVal(-ImmVal)) {
         ImmVal = -ImmVal;
-        NewUseOpc = UseOpc == ARM::t2ADDrr ? ARM::t2SUBri : ARM::t2ADDri;
+        NewUseOpc = UseOpc == ARM::t2ADDrr ? t2SUB : t2ADD;
       } else
         return false;
       SOImmValV1 = (uint32_t)ARM_AM::getT2SOImmTwoPartFirst(ImmVal);
       SOImmValV2 = (uint32_t)ARM_AM::getT2SOImmTwoPartSecond(ImmVal);
       break;
+    }
     case ARM::t2ORRrr:
     case ARM::t2EORrr:
       if (!ARM_AM::isT2SOImmTwoPartVal(ImmVal))

llvm/lib/Target/ARM/ARMInstrThumb2.td

@@ -918,10 +918,26 @@ multiclass T2I_bin_ii12rs<bits<3> op23_21, string opc, SDNode opnode,
    // The register-immediate version is re-materializable. This is useful
    // in particular for taking the address of a local.
    let isReMaterializable = 1 in {
+    def spImm : T2sTwoRegImm<
+              (outs GPRsp:$Rd), (ins GPRsp:$Rn, t2_so_imm:$imm), IIC_iALUi,
+              opc, ".w\t$Rd, $Rn, $imm",
+              []>,
+              Sched<[WriteALU, ReadALU]> {
+    let  Rn = 13;
+    let  Rd = 13;
+
+    let Inst{31-27} = 0b11110;
+    let Inst{25-24} = 0b01;
+    let Inst{23-21} = op23_21;
+    let Inst{15}    = 0;
+
+    let DecoderMethod = "DecodeT2AddSubSPImm";
+   }
+
    def ri : T2sTwoRegImm<
-               (outs GPRnopc:$Rd), (ins GPRnopc:$Rn, t2_so_imm:$imm), IIC_iALUi,
+               (outs rGPR:$Rd), (ins GPRnopc:$Rn, t2_so_imm:$imm), IIC_iALUi,
                opc, ".w\t$Rd, $Rn, $imm",
-               [(set GPRnopc:$Rd, (opnode GPRnopc:$Rn, t2_so_imm:$imm))]>,
+               [(set rGPR:$Rd, (opnode GPRnopc:$Rn, t2_so_imm:$imm))]>,
                Sched<[WriteALU, ReadALU]> {
      let Inst{31-27} = 0b11110;
      let Inst{25} = 0;
@@ -932,9 +948,9 @@ multiclass T2I_bin_ii12rs<bits<3> op23_21, string opc, SDNode opnode,
    }
    // 12-bit imm
    def ri12 : T2I<
-                  (outs GPRnopc:$Rd), (ins GPR:$Rn, imm0_4095:$imm), IIC_iALUi,
+                  (outs rGPR:$Rd), (ins GPR:$Rn, imm0_4095:$imm), IIC_iALUi,
                   !strconcat(opc, "w"), "\t$Rd, $Rn, $imm",
-                  [(set GPRnopc:$Rd, (opnode GPR:$Rn, imm0_4095:$imm))]>,
+                  [(set rGPR:$Rd, (opnode GPR:$Rn, imm0_4095:$imm))]>,
                   Sched<[WriteALU, ReadALU]> {
      bits<4> Rd;
      bits<4> Rn;
@@ -950,6 +966,26 @@ multiclass T2I_bin_ii12rs<bits<3> op23_21, string opc, SDNode opnode,
      let Inst{11-8} = Rd;
      let Inst{7-0} = imm{7-0};
    }
+     def spImm12 : T2I<
+                    (outs GPRsp:$Rd), (ins GPRsp:$Rn, imm0_4095:$imm), IIC_iALUi,
+                    !strconcat(opc, "w"), "\t$Rd, $Rn, $imm",
+                    []>,
+                    Sched<[WriteALU, ReadALU]> {
+       bits<4> Rd = 13;
+       bits<4> Rn = 13;
+       bits<12> imm;
+       let Inst{31-27} = 0b11110;
+       let Inst{26} = imm{11};
+       let Inst{25-24} = 0b10;
+       let Inst{23-21} = op23_21;
+       let Inst{20} = 0; // The S bit.
+       let Inst{19-16} = Rn;
+       let Inst{15} = 0;
+       let Inst{14-12} = imm{10-8};
+       let Inst{11-8} = Rd;
+       let Inst{7-0} = imm{7-0};
+       let DecoderMethod = "DecodeT2AddSubSPImm";
+     }
    // register
    def rr : T2sThreeReg<(outs GPRnopc:$Rd), (ins GPRnopc:$Rn, rGPR:$Rm),
                  IIC_iALUr, opc, ".w\t$Rd, $Rn, $Rm",
@@ -2267,19 +2303,29 @@ def : t2InstSubst<"sbc${s}${p} $rd, $rn, $imm",
                  (t2ADCri rGPR:$rd, rGPR:$rn, t2_so_imm_not:$imm, pred:$p, s_cc_out:$s)>;
 
 def : t2InstSubst<"add${s}${p}.w $rd, $rn, $imm",
-                 (t2SUBri GPRnopc:$rd, GPRnopc:$rn, t2_so_imm_neg:$imm, pred:$p, s_cc_out:$s)>;
-def : t2InstSubst<"addw${p} $rd, $rn, $imm",
-                 (t2SUBri12 GPRnopc:$rd, GPR:$rn, t2_so_imm_neg:$imm, pred:$p)>;
+                 (t2SUBri rGPR:$rd, GPRnopc:$rn, t2_so_imm_neg:$imm, pred:$p, s_cc_out:$s)>;
 def : t2InstSubst<"sub${s}${p}.w $rd, $rn, $imm",
-                 (t2ADDri GPRnopc:$rd, GPRnopc:$rn, t2_so_imm_neg:$imm, pred:$p, s_cc_out:$s)>;
-def : t2InstSubst<"subw${p} $rd, $rn, $imm",
-                 (t2ADDri12 GPRnopc:$rd, GPR:$rn, t2_so_imm_neg:$imm, pred:$p)>;
+                 (t2ADDri rGPR:$rd, GPRnopc:$rn, t2_so_imm_neg:$imm, pred:$p, s_cc_out:$s)>;
 def : t2InstSubst<"subw${p} $Rd, $Rn, $imm",
-                 (t2ADDri12 GPRnopc:$Rd, GPR:$Rn, imm0_4095_neg:$imm, pred:$p)>;
+                 (t2ADDri12 rGPR:$Rd, GPR:$Rn, imm0_4095_neg:$imm, pred:$p)>;
 def : t2InstSubst<"sub${s}${p} $rd, $rn, $imm",
-                 (t2ADDri GPRnopc:$rd, GPRnopc:$rn, t2_so_imm_neg:$imm, pred:$p, s_cc_out:$s)>;
+                 (t2ADDri rGPR:$rd, GPRnopc:$rn, t2_so_imm_neg:$imm, pred:$p, s_cc_out:$s)>;
 def : t2InstSubst<"sub${p} $rd, $rn, $imm",
-                 (t2ADDri12 GPRnopc:$rd, GPR:$rn, t2_so_imm_neg:$imm, pred:$p)>;
+                 (t2ADDri12 rGPR:$rd, GPR:$rn, imm0_4095_neg:$imm, pred:$p)>;
+
+// SP to SP alike
+def : t2InstSubst<"add${s}${p}.w $rd, $rn, $imm",
+                 (t2SUBspImm GPRsp:$rd, GPRsp:$rn, t2_so_imm_neg:$imm, pred:$p, s_cc_out:$s)>;
+def : t2InstSubst<"sub${s}${p}.w $rd, $rn, $imm",
+                 (t2ADDspImm GPRsp:$rd, GPRsp:$rn, t2_so_imm_neg:$imm, pred:$p, s_cc_out:$s)>;
+def : t2InstSubst<"subw${p} $Rd, $Rn, $imm",
+                 (t2ADDspImm12 GPRsp:$Rd, GPRsp:$Rn, imm0_4095_neg:$imm, pred:$p)>;
+def : t2InstSubst<"sub${s}${p} $rd, $rn, $imm",
+                 (t2ADDspImm GPRsp:$rd, GPRsp:$rn, t2_so_imm_neg:$imm, pred:$p, s_cc_out:$s)>;
+def : t2InstSubst<"sub${p} $rd, $rn, $imm",
+                 (t2ADDspImm12 GPRsp:$rd, GPRsp:$rn, imm0_4095_neg:$imm, pred:$p)>;
+
+
 // RSB
 defm t2RSB  : T2I_rbin_irs  <0b1110, "rsb", sub>;
 
@@ -2295,12 +2341,12 @@ defm t2RSBS : T2I_rbin_s_is <ARMsubc>;
 // The AddedComplexity preferences the first variant over the others since
 // it can be shrunk to a 16-bit wide encoding, while the others cannot.
 let AddedComplexity = 1 in
-def : T2Pat<(add        GPR:$src, imm1_255_neg:$imm),
-            (t2SUBri    GPR:$src, imm1_255_neg:$imm)>;
-def : T2Pat<(add        GPR:$src, t2_so_imm_neg:$imm),
-            (t2SUBri    GPR:$src, t2_so_imm_neg:$imm)>;
-def : T2Pat<(add        GPR:$src, imm0_4095_neg:$imm),
-            (t2SUBri12  GPR:$src, imm0_4095_neg:$imm)>;
+def : T2Pat<(add        rGPR:$src, imm1_255_neg:$imm),
+            (t2SUBri    rGPR:$src, imm1_255_neg:$imm)>;
+def : T2Pat<(add        rGPR:$src, t2_so_imm_neg:$imm),
+            (t2SUBri    rGPR:$src, t2_so_imm_neg:$imm)>;
+def : T2Pat<(add        rGPR:$src, imm0_4095_neg:$imm),
+            (t2SUBri12  rGPR:$src, imm0_4095_neg:$imm)>;
 def : T2Pat<(add        GPR:$src, imm0_65535_neg:$imm),
             (t2SUBrr    GPR:$src, (t2MOVi16 (imm_neg_XFORM imm:$imm)))>;
 
@@ -2799,10 +2845,10 @@ def : T2Pat<(t2_so_imm_not:$src),
 // Thumb2SizeReduction's chances later on we select a t2ADD for an or where
 // possible.
 def : T2Pat<(or AddLikeOrOp:$Rn, t2_so_imm:$imm),
-            (t2ADDri $Rn, t2_so_imm:$imm)>;
+            (t2ADDri rGPR:$Rn, t2_so_imm:$imm)>;
 
 def : T2Pat<(or AddLikeOrOp:$Rn, imm0_4095:$Rm),
-            (t2ADDri12 $Rn, imm0_4095:$Rm)>;
+            (t2ADDri12 rGPR:$Rn, imm0_4095:$Rm)>;
 
 def : T2Pat<(or AddLikeOrOp:$Rn, non_imm32:$Rm),
             (t2ADDrr $Rn, $Rm)>;
@@ -4666,20 +4712,22 @@ def : t2InstAlias<"sbc${s}${p} $Rd, $Rn, $ShiftedRm",
 
 // Aliases for ADD without the ".w" optional width specifier.
 def : t2InstAlias<"add${s}${p} $Rd, $Rn, $imm",
-        (t2ADDri GPRnopc:$Rd, GPRnopc:$Rn, t2_so_imm:$imm, pred:$p,
+        (t2ADDri rGPR:$Rd, GPRnopc:$Rn, t2_so_imm:$imm, pred:$p,
          cc_out:$s)>;
 def : t2InstAlias<"add${p} $Rd, $Rn, $imm",
-           (t2ADDri12 GPRnopc:$Rd, GPR:$Rn, imm0_4095:$imm, pred:$p)>;
+           (t2ADDri12 rGPR:$Rd, GPR:$Rn, imm0_4095:$imm, pred:$p)>;
 def : t2InstAlias<"add${s}${p} $Rd, $Rn, $Rm",
               (t2ADDrr GPRnopc:$Rd, GPRnopc:$Rn, rGPR:$Rm, pred:$p, cc_out:$s)>;
 def : t2InstAlias<"add${s}${p} $Rd, $Rn, $ShiftedRm",
                   (t2ADDrs GPRnopc:$Rd, GPRnopc:$Rn, t2_so_reg:$ShiftedRm,
                            pred:$p, cc_out:$s)>;
 // ... and with the destination and source register combined.
 def : t2InstAlias<"add${s}${p} $Rdn, $imm",
-      (t2ADDri GPRnopc:$Rdn, GPRnopc:$Rdn, t2_so_imm:$imm, pred:$p, cc_out:$s)>;
+      (t2ADDri rGPR:$Rdn, rGPR:$Rdn, t2_so_imm:$imm, pred:$p, cc_out:$s)>;
 def : t2InstAlias<"add${p} $Rdn, $imm",
-           (t2ADDri12 GPRnopc:$Rdn, GPRnopc:$Rdn, imm0_4095:$imm, pred:$p)>;
+           (t2ADDri12 rGPR:$Rdn, rGPR:$Rdn, imm0_4095:$imm, pred:$p)>;
+def : t2InstAlias<"addw${p} $Rdn, $imm",
+           (t2ADDri12 rGPR:$Rdn, rGPR:$Rdn, imm0_4095:$imm, pred:$p)>;
 def : t2InstAlias<"add${s}${p} $Rdn, $Rm",
             (t2ADDrr GPRnopc:$Rdn, GPRnopc:$Rdn, rGPR:$Rm, pred:$p, cc_out:$s)>;
 def : t2InstAlias<"add${s}${p} $Rdn, $ShiftedRm",
@@ -4688,43 +4736,45 @@ def : t2InstAlias<"add${s}${p} $Rdn, $ShiftedRm",
 
 // add w/ negative immediates is just a sub.
 def : t2InstSubst<"add${s}${p} $Rd, $Rn, $imm",
-        (t2SUBri GPRnopc:$Rd, GPRnopc:$Rn, t2_so_imm_neg:$imm, pred:$p,
+        (t2SUBri rGPR:$Rd, GPRnopc:$Rn, t2_so_imm_neg:$imm, pred:$p,
                  cc_out:$s)>;
 def : t2InstSubst<"add${p} $Rd, $Rn, $imm",
-           (t2SUBri12 GPRnopc:$Rd, GPR:$Rn, imm0_4095_neg:$imm, pred:$p)>;
+           (t2SUBri12 rGPR:$Rd, GPR:$Rn, imm0_4095_neg:$imm, pred:$p)>;
 def : t2InstSubst<"add${s}${p} $Rdn, $imm",
-      (t2SUBri GPRnopc:$Rdn, GPRnopc:$Rdn, t2_so_imm_neg:$imm, pred:$p,
+      (t2SUBri rGPR:$Rdn, rGPR:$Rdn, t2_so_imm_neg:$imm, pred:$p,
                cc_out:$s)>;
 def : t2InstSubst<"add${p} $Rdn, $imm",
-           (t2SUBri12 GPRnopc:$Rdn, GPRnopc:$Rdn, imm0_4095_neg:$imm, pred:$p)>;
+           (t2SUBri12 rGPR:$Rdn, rGPR:$Rdn, imm0_4095_neg:$imm, pred:$p)>;
 
 def : t2InstSubst<"add${s}${p}.w $Rd, $Rn, $imm",
-        (t2SUBri GPRnopc:$Rd, GPRnopc:$Rn, t2_so_imm_neg:$imm, pred:$p,
+        (t2SUBri rGPR:$Rd, GPRnopc:$Rn, t2_so_imm_neg:$imm, pred:$p,
                  cc_out:$s)>;
 def : t2InstSubst<"addw${p} $Rd, $Rn, $imm",
-           (t2SUBri12 GPRnopc:$Rd, GPR:$Rn, imm0_4095_neg:$imm, pred:$p)>;
+           (t2SUBri12 rGPR:$Rd, rGPR:$Rn, imm0_4095_neg:$imm, pred:$p)>;
 def : t2InstSubst<"add${s}${p}.w $Rdn, $imm",
-      (t2SUBri GPRnopc:$Rdn, GPRnopc:$Rdn, t2_so_imm_neg:$imm, pred:$p,
+      (t2SUBri rGPR:$Rdn, rGPR:$Rdn, t2_so_imm_neg:$imm, pred:$p,
                cc_out:$s)>;
 def : t2InstSubst<"addw${p} $Rdn, $imm",
-           (t2SUBri12 GPRnopc:$Rdn, GPRnopc:$Rdn, imm0_4095_neg:$imm, pred:$p)>;
+           (t2SUBri12 rGPR:$Rdn, rGPR:$Rdn, imm0_4095_neg:$imm, pred:$p)>;
 
 
 // Aliases for SUB without the ".w" optional width specifier.
 def : t2InstAlias<"sub${s}${p} $Rd, $Rn, $imm",
-        (t2SUBri GPRnopc:$Rd, GPRnopc:$Rn, t2_so_imm:$imm, pred:$p, cc_out:$s)>;
+        (t2SUBri rGPR:$Rd, GPRnopc:$Rn, t2_so_imm:$imm, pred:$p, cc_out:$s)>;
 def : t2InstAlias<"sub${p} $Rd, $Rn, $imm",
-           (t2SUBri12 GPRnopc:$Rd, GPR:$Rn, imm0_4095:$imm, pred:$p)>;
+           (t2SUBri12 rGPR:$Rd, GPR:$Rn, imm0_4095:$imm, pred:$p)>;
 def : t2InstAlias<"sub${s}${p} $Rd, $Rn, $Rm",
               (t2SUBrr GPRnopc:$Rd, GPRnopc:$Rn, rGPR:$Rm, pred:$p, cc_out:$s)>;
 def : t2InstAlias<"sub${s}${p} $Rd, $Rn, $ShiftedRm",
                   (t2SUBrs GPRnopc:$Rd, GPRnopc:$Rn, t2_so_reg:$ShiftedRm,
                            pred:$p, cc_out:$s)>;
 // ... and with the destination and source register combined.
 def : t2InstAlias<"sub${s}${p} $Rdn, $imm",
-      (t2SUBri GPRnopc:$Rdn, GPRnopc:$Rdn, t2_so_imm:$imm, pred:$p, cc_out:$s)>;
+      (t2SUBri rGPR:$Rdn, rGPR:$Rdn, t2_so_imm:$imm, pred:$p, cc_out:$s)>;
 def : t2InstAlias<"sub${p} $Rdn, $imm",
-           (t2SUBri12 GPRnopc:$Rdn, GPRnopc:$Rdn, imm0_4095:$imm, pred:$p)>;
+           (t2SUBri12 rGPR:$Rdn, rGPR:$Rdn, imm0_4095:$imm, pred:$p)>;
+def : t2InstAlias<"subw${p} $Rdn, $imm",
+           (t2SUBri12 rGPR:$Rdn, rGPR:$Rdn, imm0_4095:$imm, pred:$p)>;
 def : t2InstAlias<"sub${s}${p}.w $Rdn, $Rm",
             (t2SUBrr GPRnopc:$Rdn, GPRnopc:$Rdn, rGPR:$Rm, pred:$p, cc_out:$s)>;
 def : t2InstAlias<"sub${s}${p} $Rdn, $Rm",
@@ -4733,6 +4783,65 @@ def : t2InstAlias<"sub${s}${p} $Rdn, $ShiftedRm",
                   (t2SUBrs GPRnopc:$Rdn, GPRnopc:$Rdn, t2_so_reg:$ShiftedRm,
                            pred:$p, cc_out:$s)>;
 
+// SP to SP alike aliases
+// Aliases for ADD without the ".w" optional width specifier.
+def : t2InstAlias<"add${s}${p} $Rd, $Rn, $imm",
+        (t2ADDspImm GPRsp:$Rd, GPRsp:$Rn, t2_so_imm:$imm, pred:$p,
+         cc_out:$s)>;
+def : t2InstAlias<"add${p} $Rd, $Rn, $imm",
+           (t2ADDspImm12 GPRsp:$Rd, GPRsp:$Rn, imm0_4095:$imm, pred:$p)>;
+// ... and with the destination and source register combined.
+def : t2InstAlias<"add${s}${p} $Rdn, $imm",
+      (t2ADDspImm GPRsp:$Rdn, GPRsp:$Rdn, t2_so_imm:$imm, pred:$p, cc_out:$s)>;
+
+def : t2InstAlias<"add${s}${p}.w $Rdn, $imm",
+      (t2ADDspImm GPRsp:$Rdn, GPRsp:$Rdn, t2_so_imm:$imm, pred:$p, cc_out:$s)>;
+
+def : t2InstAlias<"add${p} $Rdn, $imm",
+           (t2ADDspImm12 GPRsp:$Rdn, GPRsp:$Rdn, imm0_4095:$imm, pred:$p)>;
+
+def : t2InstAlias<"addw${p} $Rdn, $imm",
+           (t2ADDspImm12 GPRsp:$Rdn, GPRsp:$Rdn, imm0_4095:$imm, pred:$p)>;
+
+// add w/ negative immediates is just a sub.
+def : t2InstSubst<"add${s}${p} $Rd, $Rn, $imm",
+        (t2SUBspImm GPRsp:$Rd, GPRsp:$Rn, t2_so_imm_neg:$imm, pred:$p,
+                 cc_out:$s)>;
+def : t2InstSubst<"add${p} $Rd, $Rn, $imm",
+           (t2SUBspImm12 GPRsp:$Rd, GPRsp:$Rn, imm0_4095_neg:$imm, pred:$p)>;
+def : t2InstSubst<"add${s}${p} $Rdn, $imm",
+      (t2SUBspImm GPRsp:$Rdn, GPRsp:$Rdn, t2_so_imm_neg:$imm, pred:$p,
+               cc_out:$s)>;
+def : t2InstSubst<"add${p} $Rdn, $imm",
+           (t2SUBspImm12 GPRsp:$Rdn, GPRsp:$Rdn, imm0_4095_neg:$imm, pred:$p)>;
+
+def : t2InstSubst<"add${s}${p}.w $Rd, $Rn, $imm",
+        (t2SUBspImm GPRsp:$Rd, GPRsp:$Rn, t2_so_imm_neg:$imm, pred:$p,
+                 cc_out:$s)>;
+def : t2InstSubst<"addw${p} $Rd, $Rn, $imm",
+           (t2SUBspImm12 GPRsp:$Rd, GPRsp:$Rn, imm0_4095_neg:$imm, pred:$p)>;
+def : t2InstSubst<"add${s}${p}.w $Rdn, $imm",
+      (t2SUBspImm GPRsp:$Rdn, GPRsp:$Rdn, t2_so_imm_neg:$imm, pred:$p,
+               cc_out:$s)>;
+def : t2InstSubst<"addw${p} $Rdn, $imm",
+           (t2SUBspImm12 GPRsp:$Rdn, GPRsp:$Rdn, imm0_4095_neg:$imm, pred:$p)>;
+
+
+// Aliases for SUB without the ".w" optional width specifier.
+def : t2InstAlias<"sub${s}${p} $Rd, $Rn, $imm",
+        (t2SUBspImm GPRsp:$Rd, GPRsp:$Rn, t2_so_imm:$imm, pred:$p, cc_out:$s)>;
+def : t2InstAlias<"sub${p} $Rd, $Rn, $imm",
+           (t2SUBspImm12 GPRsp:$Rd, GPRsp:$Rn, imm0_4095:$imm, pred:$p)>;
+// ... and with the destination and source register combined.
+def : t2InstAlias<"sub${s}${p} $Rdn, $imm",
+      (t2SUBspImm GPRsp:$Rdn, GPRsp:$Rdn, t2_so_imm:$imm, pred:$p, cc_out:$s)>;
+def : t2InstAlias<"sub${s}${p}.w $Rdn, $imm",
+      (t2SUBspImm GPRsp:$Rdn, GPRsp:$Rdn, t2_so_imm:$imm, pred:$p, cc_out:$s)>;
+def : t2InstAlias<"sub${p} $Rdn, $imm",
+           (t2SUBspImm12 GPRsp:$Rdn, GPRsp:$Rdn, imm0_4095:$imm, pred:$p)>;
+def : t2InstAlias<"subw${p} $Rdn, $imm",
+           (t2SUBspImm12 GPRsp:$Rdn, GPRsp:$Rdn, imm0_4095:$imm, pred:$p)>;
+
 // Alias for compares without the ".w" optional width specifier.
 def : t2InstAlias<"cmn${p} $Rn, $Rm",
                   (t2CMNzrr GPRnopc:$Rn, rGPR:$Rm, pred:$p)>;
@@ -4989,10 +5098,16 @@ def : t2InstSubst<"orr${s}${p} $Rdn, $imm",
                            pred:$p, cc_out:$s)>;
 // Likewise, "add Rd, t2_so_imm_neg" -> sub
 def : t2InstSubst<"add${s}${p} $Rd, $Rn, $imm",
-                  (t2SUBri GPRnopc:$Rd, GPRnopc:$Rn, t2_so_imm_neg:$imm,
+                  (t2SUBri rGPR:$Rd, GPRnopc:$Rn, t2_so_imm_neg:$imm,
+                           pred:$p, cc_out:$s)>;
+def : t2InstSubst<"add${s}${p} $Rd, $Rn, $imm",
+                  (t2SUBspImm GPRsp:$Rd, GPRsp:$Rn, t2_so_imm_neg:$imm,
+                           pred:$p, cc_out:$s)>;
+def : t2InstSubst<"add${s}${p} $Rd, $imm",
+                  (t2SUBri rGPR:$Rd, rGPR:$Rd, t2_so_imm_neg:$imm,
                            pred:$p, cc_out:$s)>;
 def : t2InstSubst<"add${s}${p} $Rd, $imm",
-                  (t2SUBri GPRnopc:$Rd, GPRnopc:$Rd, t2_so_imm_neg:$imm,
+                  (t2SUBspImm GPRsp:$Rd, GPRsp:$Rd, t2_so_imm_neg:$imm,
                            pred:$p, cc_out:$s)>;
 // Same for CMP <--> CMN via t2_so_imm_neg
 def : t2InstSubst<"cmp${p} $Rd, $imm",

llvm/lib/Target/ARM/ARMLoadStoreOptimizer.cpp

@@ -696,18 +696,23 @@ MachineInstr *ARMLoadStoreOpt::CreateLoadStoreMulti(
         return nullptr;
     }
 
-    int BaseOpc =
-      isThumb2 ? ARM::t2ADDri :
-      (isThumb1 && Base == ARM::SP) ? ARM::tADDrSPi :
-      (isThumb1 && Offset < 8) ? ARM::tADDi3 :
-      isThumb1 ? ARM::tADDi8  : ARM::ADDri;
+    int BaseOpc = isThumb2 ? (BaseKill && Base == ARM::SP ? ARM::t2ADDspImm
+                                                          : ARM::t2ADDri)
+                           : (isThumb1 && Base == ARM::SP)
+                                 ? ARM::tADDrSPi
+                                 : (isThumb1 && Offset < 8)
+                                       ? ARM::tADDi3
+                                       : isThumb1 ? ARM::tADDi8 : ARM::ADDri;
 
     if (Offset < 0) {
-      Offset = - Offset;
-      BaseOpc =
-        isThumb2 ? ARM::t2SUBri :
-        (isThumb1 && Offset < 8 && Base != ARM::SP) ? ARM::tSUBi3 :
-        isThumb1 ? ARM::tSUBi8  : ARM::SUBri;
+      // FIXME: There are no Thumb1 load/store instructions with negative
+      // offsets. So the Base != ARM::SP might be unnecessary.
+      Offset = -Offset;
+      BaseOpc = isThumb2 ? (BaseKill && Base == ARM::SP ? ARM::t2SUBspImm
+                                                        : ARM::t2SUBri)
+                         : (isThumb1 && Offset < 8 && Base != ARM::SP)
+                               ? ARM::tSUBi3
+                               : isThumb1 ? ARM::tSUBi8 : ARM::SUBri;
     }
 
     if (!TL->isLegalAddImmediate(Offset))
@@ -1186,8 +1191,10 @@ static int isIncrementOrDecrement(const MachineInstr &MI, unsigned Reg,
   case ARM::tADDi8:  Scale =  4; CheckCPSRDef = true; break;
   case ARM::tSUBi8:  Scale = -4; CheckCPSRDef = true; break;
   case ARM::t2SUBri:
+  case ARM::t2SUBspImm:
   case ARM::SUBri:   Scale = -1; CheckCPSRDef = true; break;
   case ARM::t2ADDri:
+  case ARM::t2ADDspImm:
   case ARM::ADDri:   Scale =  1; CheckCPSRDef = true; break;
   case ARM::tADDspi: Scale =  4; CheckCPSRDef = false; break;
   case ARM::tSUBspi: Scale = -4; CheckCPSRDef = false; break;