SystemZ: Fold copy of vector immediate to gr128 (#90706)

If materializing a constant in a vector register that is just
going to be copied to general registers, directly materialize
the immediate in the gpr. This will avoid a few lit test regressions
in a future commit.

3 files changed, 243 insertions, 0 deletions

diff --git a/llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp b/llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp
index 8176eba74b73..3238b62218db 100644
--- a/llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp
@@ -640,6 +640,51 @@ bool SystemZInstrInfo::foldImmediate(MachineInstr &UseMI, MachineInstr &DefMI,
                                      Register Reg,
                                      MachineRegisterInfo *MRI) const {
   unsigned DefOpc = DefMI.getOpcode();
+
+  if (DefOpc == SystemZ::VGBM) {
+    int64_t ImmVal = DefMI.getOperand(1).getImm();
+    if (ImmVal != 0) // TODO: Handle other values
+      return false;
+
+    // Fold gr128 = COPY (vr128 VGBM imm)
+    //
+    // %tmp:gr64 = LGHI 0
+    // to  gr128 = REG_SEQUENCE %tmp, %tmp
+    assert(DefMI.getOperand(0).getReg() == Reg);
+
+    if (!UseMI.isCopy())
+      return false;
+
+    Register CopyDstReg = UseMI.getOperand(0).getReg();
+    if (CopyDstReg.isVirtual() &&
+        MRI->getRegClass(CopyDstReg) == &SystemZ::GR128BitRegClass &&
+        MRI->hasOneNonDBGUse(Reg)) {
+      // TODO: Handle physical registers
+      // TODO: Handle gr64 uses with subregister indexes
+      // TODO: Should this multi-use cases?
+      Register TmpReg = MRI->createVirtualRegister(&SystemZ::GR64BitRegClass);
+      MachineBasicBlock &MBB = *UseMI.getParent();
+
+      // FIXME: probably should be DefMI's DebugLoc but this matches
+      // loadImmediate's guessing
+      const DebugLoc &DL = UseMI.getDebugLoc();
+
+      loadImmediate(MBB, UseMI.getIterator(), TmpReg, ImmVal);
+
+      BuildMI(MBB, UseMI.getIterator(), DL, get(SystemZ::REG_SEQUENCE),
+              CopyDstReg)
+          .addReg(TmpReg)
+          .addImm(SystemZ::subreg_h64)
+          .addReg(TmpReg)
+          .addImm(SystemZ::subreg_l64);
+
+      UseMI.eraseFromParent();
+      return true;
+    }
+
+    return false;
+  }
+
   if (DefOpc != SystemZ::LHIMux && DefOpc != SystemZ::LHI &&
       DefOpc != SystemZ::LGHI)
     return false;
@@ -2237,3 +2282,16 @@ areMemAccessesTriviallyDisjoint(const MachineInstr &MIa,
 
   return false;
 }
+
+bool SystemZInstrInfo::getConstValDefinedInReg(const MachineInstr &MI,
+                                               const Register Reg,
+                                               int64_t &ImmVal) const {
+
+  if (MI.getOpcode() == SystemZ::VGBM && Reg == MI.getOperand(0).getReg()) {
+    ImmVal = MI.getOperand(1).getImm();
+    // TODO: Handle non-0 values
+    return ImmVal == 0;
+  }
+
+  return false;
+}
diff --git a/llvm/lib/Target/SystemZ/SystemZInstrInfo.h b/llvm/lib/Target/SystemZ/SystemZInstrInfo.h
index aa10fb564962..61338b081615 100644
--- a/llvm/lib/Target/SystemZ/SystemZInstrInfo.h
+++ b/llvm/lib/Target/SystemZ/SystemZInstrInfo.h
@@ -383,6 +383,9 @@ public:
   bool
   areMemAccessesTriviallyDisjoint(const MachineInstr &MIa,
                                   const MachineInstr &MIb) const override;
+
+  bool getConstValDefinedInReg(const MachineInstr &MI, const Register Reg,
+                               int64_t &ImmVal) const override;
 };
 
 } // end namespace llvm
diff --git a/llvm/test/CodeGen/SystemZ/fold-copy-vector-immediate.mir b/llvm/test/CodeGen/SystemZ/fold-copy-vector-immediate.mir
new file mode 100644
index 000000000000..2aee0cb521c4
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/fold-copy-vector-immediate.mir
@@ -0,0 +1,182 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 4
+# RUN: llc -mtriple=s390x-linux-gnu -mcpu=z13 -run-pass=peephole-opt -o - %s | FileCheck %s
+
+---
+name:            fold_vgbm_0_copyvr128_to_gr128_virtreg
+tracksRegLiveness: true
+body:             |
+  bb.0:
+      liveins: $r2d
+    ; CHECK-LABEL: name: fold_vgbm_0_copyvr128_to_gr128_virtreg
+    ; CHECK: liveins: $r2d
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:gr64bit = COPY $r2d
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:addr64bit = COPY [[COPY]]
+    ; CHECK-NEXT: [[VGBM:%[0-9]+]]:vr128bit = VGBM 0
+    ; CHECK-NEXT: [[LGHI:%[0-9]+]]:gr64bit = LGHI 0
+    ; CHECK-NEXT: [[REG_SEQUENCE:%[0-9]+]]:gr128bit = REG_SEQUENCE [[LGHI]], %subreg.subreg_h64, [[LGHI]], %subreg.subreg_l64
+    ; CHECK-NEXT: $r0q = COPY [[REG_SEQUENCE]]
+    ; CHECK-NEXT: Return implicit $r0q
+    %0:gr64bit = COPY $r2d
+    %1:addr64bit = COPY %0
+    %2:vr128bit = VGBM 0
+    %3:gr128bit = COPY %2
+    $r0q = COPY %3
+    Return implicit $r0q
+...
+
+---
+name:            fold_vgbm_0_copyvr128_to_gr128_virtreg_multi_use
+tracksRegLiveness: true
+body:             |
+  bb.0:
+      liveins: $r2d
+    ; CHECK-LABEL: name: fold_vgbm_0_copyvr128_to_gr128_virtreg_multi_use
+    ; CHECK: liveins: $r2d
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:gr64bit = COPY $r2d
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:addr64bit = COPY [[COPY]]
+    ; CHECK-NEXT: [[VGBM:%[0-9]+]]:vr128bit = VGBM 0
+    ; CHECK-NEXT: [[COPY2:%[0-9]+]]:gr128bit = COPY [[VGBM]]
+    ; CHECK-NEXT: $r0q = COPY [[COPY2]]
+    ; CHECK-NEXT: $r2q = COPY [[COPY2]]
+    ; CHECK-NEXT: Return implicit $r0q, implicit $r2q
+    %0:gr64bit = COPY $r2d
+    %1:addr64bit = COPY %0
+    %2:vr128bit = VGBM 0
+    %3:gr128bit = COPY %2
+    %4:gr128bit = COPY %2
+    $r0q = COPY %3
+    $r2q = COPY %4
+    Return implicit $r0q, implicit $r2q
+...
+
+---
+name:            fold_vgbm_0_copyvr128_to_gr128_physreg
+tracksRegLiveness: true
+body:             |
+  bb.0:
+      liveins: $r2d
+    ; CHECK-LABEL: name: fold_vgbm_0_copyvr128_to_gr128_physreg
+    ; CHECK: liveins: $r2d
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:gr64bit = COPY $r2d
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:addr64bit = COPY [[COPY]]
+    ; CHECK-NEXT: [[VGBM:%[0-9]+]]:vr128bit = VGBM 0
+    ; CHECK-NEXT: $r0q = COPY [[VGBM]]
+    ; CHECK-NEXT: Return implicit $r0q
+    %0:gr64bit = COPY $r2d
+    %1:addr64bit = COPY %0
+    %2:vr128bit = VGBM 0
+    $r0q = COPY %2
+    Return implicit $r0q
+...
+
+---
+name:            no_fold_vgbm_0_copyvr128_to_vr128_virtreg
+tracksRegLiveness: true
+body:             |
+  bb.0:
+      liveins: $r2d
+    ; CHECK-LABEL: name: no_fold_vgbm_0_copyvr128_to_vr128_virtreg
+    ; CHECK: liveins: $r2d
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:gr64bit = COPY $r2d
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:addr64bit = COPY [[COPY]]
+    ; CHECK-NEXT: [[VGBM:%[0-9]+]]:vr128bit = VGBM 0
+    ; CHECK-NEXT: [[COPY2:%[0-9]+]]:vr128bit = COPY [[VGBM]]
+    ; CHECK-NEXT: $v0 = COPY [[COPY2]]
+    ; CHECK-NEXT: Return implicit $v0
+    %0:gr64bit = COPY $r2d
+    %1:addr64bit = COPY %0
+    %2:vr128bit = VGBM 0
+    %3:vr128bit = COPY %2
+    $v0 = COPY %3
+    Return implicit $v0
+...
+
+---
+name:            no_fold_vgbm_0_copyvr128_to_vr128_physreg
+tracksRegLiveness: true
+body:             |
+  bb.0:
+      liveins: $r2d
+    ; CHECK-LABEL: name: no_fold_vgbm_0_copyvr128_to_vr128_physreg
+    ; CHECK: liveins: $r2d
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:gr64bit = COPY $r2d
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:addr64bit = COPY [[COPY]]
+    ; CHECK-NEXT: [[VGBM:%[0-9]+]]:vr128bit = VGBM 0
+    ; CHECK-NEXT: $v0 = COPY [[VGBM]]
+    ; CHECK-NEXT: Return implicit $v0
+    %0:gr64bit = COPY $r2d
+    %1:addr64bit = COPY %0
+    %2:vr128bit = VGBM 0
+    $v0 = COPY %2
+    Return implicit $v0
+...
+
+---
+name:            fold_vgbm_1_copyvr128_to_gr128_virtreg
+tracksRegLiveness: true
+body:             |
+  bb.0:
+      liveins: $r2d
+    ; CHECK-LABEL: name: fold_vgbm_1_copyvr128_to_gr128_virtreg
+    ; CHECK: liveins: $r2d
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:gr64bit = COPY $r2d
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:addr64bit = COPY [[COPY]]
+    ; CHECK-NEXT: [[VGBM:%[0-9]+]]:vr128bit = VGBM 1
+    ; CHECK-NEXT: [[COPY2:%[0-9]+]]:gr128bit = COPY [[VGBM]]
+    ; CHECK-NEXT: $r0q = COPY [[COPY2]]
+    ; CHECK-NEXT: Return implicit $r0q
+    %0:gr64bit = COPY $r2d
+    %1:addr64bit = COPY %0
+    %2:vr128bit = VGBM 1
+    %3:gr128bit = COPY %2
+    $r0q = COPY %3
+    Return implicit $r0q
+...
+
+---
+name:            no_fold_vgbm_0_noncopy_use
+tracksRegLiveness: true
+body:             |
+  bb.0:
+      liveins: $r2d
+    ; CHECK-LABEL: name: no_fold_vgbm_0_noncopy_use
+    ; CHECK: liveins: $r2d
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:gr64bit = COPY $r2d
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:addr64bit = COPY [[COPY]]
+    ; CHECK-NEXT: [[VGBM:%[0-9]+]]:vr128bit = VGBM 0
+    ; CHECK-NEXT: Return implicit [[VGBM]]
+    %0:gr64bit = COPY $r2d
+    %1:addr64bit = COPY %0
+    %2:vr128bit = VGBM 0
+    Return implicit %2
+...
+
+---
+name:            fold_vgbm_0_copyvr128_to_gr64_subreg_h64
+tracksRegLiveness: true
+body:             |
+  bb.0:
+      liveins: $r2d
+    ; CHECK-LABEL: name: fold_vgbm_0_copyvr128_to_gr64_subreg_h64
+    ; CHECK: liveins: $r2d
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:gr64bit = COPY $r2d
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:addr64bit = COPY [[COPY]]
+    ; CHECK-NEXT: [[VGBM:%[0-9]+]]:vr128bit = VGBM 0
+    ; CHECK-NEXT: [[COPY2:%[0-9]+]]:gr64bit = COPY [[VGBM]].subreg_h64
+    ; CHECK-NEXT: $r0d = COPY [[COPY2]]
+    ; CHECK-NEXT: Return implicit $r0d
+    %0:gr64bit = COPY $r2d
+    %1:addr64bit = COPY %0
+    %2:vr128bit = VGBM 0
+    %3:gr64bit = COPY %2.subreg_h64
+    $r0d = COPY %3
+    Return implicit $r0d
+...