[AMDGPU] Serialize WWM_REG vreg flag

Author: optimisan

llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp

@@ -1716,6 +1716,21 @@ bool GCNTargetMachine::parseMachineFunctionInfo(
     MFI->reserveWWMRegister(ParsedReg);
   }
 
+  auto setRegisterFlags = [&](const VRegInfo &Info) {
+    for (const auto &Flag : Info.Flags) {
+      MFI->setFlag(Info.VReg, Flag);
+    }
+  };
+
+  for (const auto &P : PFS.VRegInfosNamed) {
+    const VRegInfo &Info = *P.second;
+    setRegisterFlags(Info);
+  }
+  for (const auto &P : PFS.VRegInfos) {
+    const VRegInfo &Info = *P.second;
+    setRegisterFlags(Info);
+  }
+
   auto parseAndCheckArgument = [&](const std::optional<yaml::SIArgument> &A,
                                    const TargetRegisterClass &RC,
                                    ArgDescriptor &Arg, unsigned UserSGPRs,

llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.h

@@ -696,8 +696,8 @@ class SIMachineFunctionInfo final : public AMDGPUMachineFunction,
 
   void setFlag(Register Reg, uint8_t Flag) {
     assert(Reg.isVirtual());
-    if (VRegFlags.inBounds(Reg))
-      VRegFlags[Reg] |= Flag;
+    VRegFlags.grow(Reg);
+    VRegFlags[Reg] |= Flag;
   }
 
   bool checkFlag(Register Reg, uint8_t Flag) const {

llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp

@@ -3851,3 +3851,14 @@ SIRegisterInfo::getSubRegAlignmentNumBits(const TargetRegisterClass *RC,
   }
   return 0;
 }
+
+SmallVector<std::string>
+SIRegisterInfo::getVRegFlagsOfReg(Register Reg,
+                                  const MachineFunction &MF) const {
+  SmallVector<std::string> RegFlags;
+  const SIMachineFunctionInfo *FuncInfo = MF.getInfo<SIMachineFunctionInfo>();
+  if (FuncInfo->checkFlag(Reg, AMDGPU::VirtRegFlag::WWM_REG)) {
+    RegFlags.push_back("WWM_REG");
+  }
+  return RegFlags;
+}

llvm/lib/Target/AMDGPU/SIRegisterInfo.h

@@ -457,6 +457,16 @@ class SIRegisterInfo final : public AMDGPUGenRegisterInfo {
   // No check if the subreg is supported by the current RC is made.
   unsigned getSubRegAlignmentNumBits(const TargetRegisterClass *RC,
                                      unsigned SubReg) const;
+
+  std::pair<bool, uint8_t> getVRegFlagValue(StringRef Name) const override {
+    if (Name == "WWM_REG") {
+      return {true, AMDGPU::VirtRegFlag::WWM_REG};
+    }
+    return {false, 0};
+  }
+
+  SmallVector<std::string>
+  getVRegFlagsOfReg(Register Reg, const MachineFunction &MF) const override;
 };
 
 namespace AMDGPU {

llvm/test/CodeGen/AMDGPU/virtual-registers.mir

@@ -0,0 +1,16 @@
+# RUN: llc -mtriple=amdgcn -run-pass=none -o - %s | FileCheck %s
+# This test ensures that the MIR parser parses virtual register flags correctly
+
+---
+name: vregs
+# CHECK: registers:
+# CHECK-NEXT:   - { id: 0, class: vgpr_32, preferred-register: '$vgpr1', flags: [ WWM_REG ] }
+# CHECK-NEXT:   - { id: 1, class: sgpr_64, preferred-register: '$sgpr0_sgpr1', flags: [  ] }
+# CHECK-NEXT:   - { id: 2, class: sgpr_64, preferred-register: '', flags: [  ] }
+registers:
+  - { id: 0, class: vgpr_32, preferred-register: $vgpr1, flags: [ WWM_REG ]}
+  - { id: 1, class: sgpr_64, preferred-register: $sgpr0_sgpr1 }
+body: |
+  bb.0:
+    %2:sgpr_64 = COPY %1
+    %1:sgpr_64 = COPY %0