[RISCV] Add an GPR def to the Zvlseg SPILL/RELOAD pseudos

The expansion of these pseudos creates ADD instructions. Those
ADDs modify a GPR so that it is no longer contains the same value
as the input base pointer. Therefore, I believe we should have a
GPR as a Def on these instructions and expansion should get the
destination register for the ADDs from that operand.

At least in our tests here this works out so that register
scavenging picks the same register as the base pointer.

Reviewed By: frasercrmck

Differential Revision: https://reviews.llvm.org/D109405

diff --git a/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp b/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
index 80340ee..3ff6024 100644 (file)
--- a/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
+++ b/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
@@ -287,9 +287,10 @@ bool RISCVExpandPseudo::expandVSPILL(MachineBasicBlock &MBB,
   const TargetRegisterInfo *TRI =
       MBB.getParent()->getSubtarget().getRegisterInfo();
   DebugLoc DL = MBBI->getDebugLoc();
-  Register SrcReg = MBBI->getOperand(0).getReg();
-  Register Base = MBBI->getOperand(1).getReg();
-  Register VL = MBBI->getOperand(2).getReg();
+  Register AddrInc = MBBI->getOperand(0).getReg();
+  Register SrcReg = MBBI->getOperand(1).getReg();
+  Register Base = MBBI->getOperand(2).getReg();
+  Register VL = MBBI->getOperand(3).getReg();
   auto ZvlssegInfo = TII->isRVVSpillForZvlsseg(MBBI->getOpcode());
   if (!ZvlssegInfo)
     return false;
@@ -318,10 +319,12 @@ bool RISCVExpandPseudo::expandVSPILL(MachineBasicBlock &MBB,
         .addReg(TRI->getSubReg(SrcReg, SubRegIdx + I))
         .addReg(Base)
         .addMemOperand(*(MBBI->memoperands_begin()));
-    if (I != NF - 1)
-      BuildMI(MBB, MBBI, DL, TII->get(RISCV::ADD), Base)
+    if (I != NF - 1) {
+      BuildMI(MBB, MBBI, DL, TII->get(RISCV::ADD), AddrInc)
           .addReg(Base)
           .addReg(VL);
+      Base = AddrInc;
+    }
   }
   MBBI->eraseFromParent();
   return true;
@@ -333,8 +336,9 @@ bool RISCVExpandPseudo::expandVRELOAD(MachineBasicBlock &MBB,
       MBB.getParent()->getSubtarget().getRegisterInfo();
   DebugLoc DL = MBBI->getDebugLoc();
   Register DestReg = MBBI->getOperand(0).getReg();
-  Register Base = MBBI->getOperand(1).getReg();
-  Register VL = MBBI->getOperand(2).getReg();
+  Register AddrInc = MBBI->getOperand(1).getReg();
+  Register Base = MBBI->getOperand(2).getReg();
+  Register VL = MBBI->getOperand(3).getReg();
   auto ZvlssegInfo = TII->isRVVSpillForZvlsseg(MBBI->getOpcode());
   if (!ZvlssegInfo)
     return false;
@@ -363,10 +367,12 @@ bool RISCVExpandPseudo::expandVRELOAD(MachineBasicBlock &MBB,
             TRI->getSubReg(DestReg, SubRegIdx + I))
         .addReg(Base)
         .addMemOperand(*(MBBI->memoperands_begin()));
-    if (I != NF - 1)
-      BuildMI(MBB, MBBI, DL, TII->get(RISCV::ADD), Base)
+    if (I != NF - 1) {
+      BuildMI(MBB, MBBI, DL, TII->get(RISCV::ADD), AddrInc)
           .addReg(Base)
           .addReg(VL);
+      Base = AddrInc;
+    }
   }
   MBBI->eraseFromParent();
   return true;

diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index fcfd98e..c216662 100644 (file)
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -311,10 +311,17 @@ void RISCVInstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
         MemoryLocation::UnknownSize, MFI.getObjectAlign(FI));
 
     MFI.setStackID(FI, TargetStackID::ScalableVector);
-    auto MIB = BuildMI(MBB, I, DL, get(Opcode))
-                   .addReg(SrcReg, getKillRegState(IsKill))
-                   .addFrameIndex(FI)
-                   .addMemOperand(MMO);
+    auto MIB = BuildMI(MBB, I, DL, get(Opcode));
+    if (IsZvlsseg) {
+      // We need a GPR register to hold the incremented address for each subreg
+      // after expansion.
+      Register AddrInc =
+          MF->getRegInfo().createVirtualRegister(&RISCV::GPRRegClass);
+      MIB.addReg(AddrInc, RegState::Define);
+    }
+    MIB.addReg(SrcReg, getKillRegState(IsKill))
+        .addFrameIndex(FI)
+        .addMemOperand(MMO);
     if (IsZvlsseg) {
       // For spilling/reloading Zvlsseg registers, append the dummy field for
       // the scaled vector length. The argument will be used when expanding
@@ -405,9 +412,15 @@ void RISCVInstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
         MemoryLocation::UnknownSize, MFI.getObjectAlign(FI));
 
     MFI.setStackID(FI, TargetStackID::ScalableVector);
-    auto MIB = BuildMI(MBB, I, DL, get(Opcode), DstReg)
-                   .addFrameIndex(FI)
-                   .addMemOperand(MMO);
+    auto MIB = BuildMI(MBB, I, DL, get(Opcode), DstReg);
+    if (IsZvlsseg) {
+      // We need a GPR register to hold the incremented address for each subreg
+      // after expansion.
+      Register AddrInc =
+          MF->getRegInfo().createVirtualRegister(&RISCV::GPRRegClass);
+      MIB.addReg(AddrInc, RegState::Define);
+    }
+    MIB.addFrameIndex(FI).addMemOperand(MMO);
     if (IsZvlsseg) {
       // For spilling/reloading Zvlsseg registers, append the dummy field for
       // the scaled vector length. The argument will be used when expanding

diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoVPseudos.td b/llvm/lib/Target/RISCV/RISCVInstrInfoVPseudos.td
index e8b4300..1ebc082 100644 (file)
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoVPseudos.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoVPseudos.td
@@ -3356,11 +3356,11 @@ foreach lmul = MxList.m in {
     defvar vreg = SegRegClass<lmul, nf>.RC;
     let hasSideEffects = 0, mayLoad = 0, mayStore = 1, isCodeGenOnly = 1 in {
       def "PseudoVSPILL" # nf # "_" # lmul.MX :
-        Pseudo<(outs), (ins vreg:$rs1, GPR:$rs2, GPR:$vlenb), []>;
+        Pseudo<(outs GPR:$addrinc), (ins vreg:$rs1, GPR:$rs2, GPR:$vlenb), []>;
     }
     let hasSideEffects = 0, mayLoad = 1, mayStore = 0, isCodeGenOnly = 1 in {
       def "PseudoVRELOAD" # nf # "_" # lmul.MX :
-        Pseudo<(outs vreg:$rs1), (ins GPR:$rs2, GPR:$vlenb), []>;
+        Pseudo<(outs vreg:$rs1, GPR:$addrinc), (ins GPR:$rs2, GPR:$vlenb), []>;
     }
   }
 }

diff --git a/llvm/test/CodeGen/RISCV/rvv/zvlsseg-spill.mir b/llvm/test/CodeGen/RISCV/rvv/zvlsseg-spill.mir
index c8ec113..cbde256 100644 (file)
--- a/llvm/test/CodeGen/RISCV/rvv/zvlsseg-spill.mir
+++ b/llvm/test/CodeGen/RISCV/rvv/zvlsseg-spill.mir
@@ -29,10 +29,10 @@ body: |
     ; CHECK: $v0_v1_v2_v3_v4_v5_v6 = PseudoVLSEG7E64_V_M1 renamable $x10, $noreg, 6, implicit $vl, implicit $vtype
     ; CHECK: $x11 = ADDI $x2, 16
     ; CHECK: $x12 = PseudoReadVLENB
-    ; CHECK: PseudoVSPILL7_M1 killed renamable $v0_v1_v2_v3_v4_v5_v6, killed $x11, killed $x12
+    ; CHECK: dead renamable $x11 = PseudoVSPILL7_M1 killed renamable $v0_v1_v2_v3_v4_v5_v6, killed $x11, killed $x12
     ; CHECK: $x11 = ADDI $x2, 16
     ; CHECK: $x12 = PseudoReadVLENB
-    ; CHECK: dead renamable $v7_v8_v9_v10_v11_v12_v13 = PseudoVRELOAD7_M1 killed $x11, killed $x12, implicit-def $v8
+    ; CHECK: dead renamable $v7_v8_v9_v10_v11_v12_v13, dead renamable $x11 = PseudoVRELOAD7_M1 killed $x11, killed $x12, implicit-def $v8
     ; CHECK: VS1R_V killed $v8, killed renamable $x10
     ; CHECK: $x10 = frame-destroy PseudoReadVLENB
     ; CHECK: $x10 = frame-destroy SLLI killed $x10, 3
@@ -42,8 +42,8 @@ body: |
     %0:gpr = COPY $x10
     %1:gprnox0 = COPY $x11
     $v0_v1_v2_v3_v4_v5_v6 = PseudoVLSEG7E64_V_M1 %0, %1, 6
-    PseudoVSPILL7_M1 killed renamable $v0_v1_v2_v3_v4_v5_v6, %stack.0, $x0
-    renamable $v7_v8_v9_v10_v11_v12_v13 = PseudoVRELOAD7_M1 %stack.0, $x0
+    %2:gpr = PseudoVSPILL7_M1 killed renamable $v0_v1_v2_v3_v4_v5_v6, %stack.0, $x0
+    renamable $v7_v8_v9_v10_v11_v12_v13, %3:gpr = PseudoVRELOAD7_M1 %stack.0, $x0
     VS1R_V killed $v8, %0:gpr
     PseudoRET
 ...