[mips] Enable spilling and reloading of the dsp register set.

The dsp register class is an alias of the gpr register class, so
we have to define instructions for spilling and reloading.

Reviewers: atanasyan

Differential Revision: https://reviews.llvm.org/D38038

llvm-svn: 314798

Author: Simon Dardis

llvm/lib/Target/Mips/MicroMipsDSPInstrInfo.td

@@ -415,6 +415,13 @@ class BITREV_MM_DESC : ABSQ_S_PH_MM_R2_DESC_BASE<"bitrev", int_mips_bitrev,
 class BPOSGE32_MM_DESC : BPOSGE32_DESC_BASE<"bposge32", brtarget_mm,
                                             NoItinerary>;
 
+let DecoderNamespace = "MicroMipsDSP", Arch = "mmdsp",
+    AdditionalPredicates = [HasDSP, InMicroMips] in {
+    def LWDSP_MM : Load<"lw", DSPROpnd, null_frag, II_LW>, DspMMRel,
+                   LW_FM_MM<0x3f>;
+    def SWDSP_MM : Store<"sw", DSPROpnd, null_frag, II_SW>, DspMMRel,
+                   LW_FM_MM<0x3e>;
+}
 // Instruction defs.
 // microMIPS DSP Rev 1
 def ADDQ_PH_MM : DspMMRel, ADDQ_PH_MM_ENC, ADDQ_PH_DESC;

llvm/lib/Target/Mips/MipsDSPInstrInfo.td

@@ -1284,6 +1284,12 @@ let isPseudo = 1, isCodeGenOnly = 1, hasNoSchedulingInfo = 1 in {
   def STORE_CCOND_DSP : Store<"store_ccond_dsp", DSPCC>;
 }
 
+let DecoderNamespace = "MipsDSP", Arch = "dsp",
+    AdditionalPredicates = [HasDSP] in {
+  def LWDSP : Load<"lw", DSPROpnd, null_frag, II_LW>, DspMMRel, LW_FM<0x23>;
+  def SWDSP : Store<"sw", DSPROpnd, null_frag, II_SW>, DspMMRel, LW_FM<0x2b>;
+}
+
 // Pseudo CMP and PICK instructions.
 class PseudoCMP<Instruction RealInst> :
   PseudoDSP<(outs DSPCC:$cmp), (ins DSPROpnd:$rs, DSPROpnd:$rt), []>,

llvm/lib/Target/Mips/MipsSEInstrInfo.cpp

@@ -226,6 +226,8 @@ storeRegToStack(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
     Opc = Mips::SW;
   else if (Mips::HI64RegClass.hasSubClassEq(RC))
     Opc = Mips::SD;
+  else if (Mips::DSPRRegClass.hasSubClassEq(RC))
+    Opc = Mips::SWDSP;
 
   // Hi, Lo are normally caller save but they are callee save
   // for interrupt handling.
@@ -302,6 +304,8 @@ loadRegFromStack(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
     Opc = Mips::LW;
   else if (Mips::LO64RegClass.hasSubClassEq(RC))
     Opc = Mips::LD;
+  else if (Mips::DSPRRegClass.hasSubClassEq(RC))
+    Opc = Mips::LWDSP;
 
   assert(Opc && "Register class not handled!");
 

llvm/test/CodeGen/Mips/dsp-spill-reload.ll

@@ -0,0 +1,52 @@
+; RUN: llc -march=mips -mattr=+dsp < %s -asm-show-inst -O0 | FileCheck %s \
+; RUN:   --check-prefixes=ASM,ALL
+; RUN: llc -march=mips -mattr=+dsp,+micromips < %s -O0 -filetype=obj | \
+; RUN:   llvm-objdump -d - | FileCheck %s --check-prefixes=MM-OBJ,ALL
+
+; Test that spill and reloads use the dsp "variant" instructions. We use -O0
+; to use the simple register allocator.
+
+; To test the micromips output, we have to take a round trip through the
+; object file encoder/decoder as the instruction mapping tables are used to
+; support micromips.
+
+; FIXME: We should be able to get rid of those instructions with the variable
+;        value registers.
+
+; ALL-LABEL: spill_reload:
+
+define <4 x i8>  @spill_reload(<4 x i8> %a, <4 x i8> %b, i32 %g) {
+entry:
+  %c = tail call <4 x i8> @llvm.mips.addu.qb(<4 x i8> %a, <4 x i8> %b)
+  %cond = icmp eq i32 %g, 0
+  br i1 %cond, label %true, label %end
+
+; ASM: SWDSP
+; ASM: SWDSP
+; ASM: SWDSP
+
+; MM-OBJ:   sw  ${{[0-9]+}}, {{[0-9]+}}($sp)
+; MM-OBJ:   sw  ${{[0-9]+}}, {{[0-9]+}}($sp)
+; MM-OBJ:   sw  ${{[0-9]+}}, {{[0-9]+}}($sp)
+; MM-OBJ:   sw  ${{[0-9]+}}, {{[0-9]+}}($sp)
+
+true:
+  ret <4 x i8> %c
+
+; ASM: LWDSP
+
+; MM-OBJ: lw ${{[0-9]+}}, {{[0-9]+}}($sp)
+
+end:
+  %d = tail call <4 x i8> @llvm.mips.addu.qb(<4 x i8> %c, <4 x i8> %a)
+  ret <4 x i8> %d
+
+; ASM: LWDSP
+; ASM: LWDSP
+
+; MM-OBJ: lw ${{[0-9]+}}, {{[0-9]+}}($sp)
+; MM-OBJ: lw ${{[0-9]+}}, {{[0-9]+}}($sp)
+
+}
+
+declare <4 x i8> @llvm.mips.addu.qb(<4 x i8>, <4 x i8>) nounwind