Revert "Remove unnecessary call to getAllocatableRegClass"

This reverts commit r252565.

This also includes the revert of the commit mentioned below in order to
avoid breaking tests in AMDGPU:

Revert "AMDGPU: Set isAllocatable = 0 on VS_32/VS_64"

This reverts commit r252674.

llvm-svn: 252956

lib/CodeGen/SelectionDAG/InstrEmitter.cpp

@@ -330,15 +330,11 @@ InstrEmitter::AddRegisterOperand(MachineInstrBuilder &MIB,
   // shrink VReg's register class within reason.  For example, if VReg == GR32
   // and II requires a GR32_NOSP, just constrain VReg to GR32_NOSP.
   if (II) {
-    const TargetRegisterClass *OpRC = nullptr;
+    const TargetRegisterClass *DstRC = nullptr;
     if (IIOpNum < II->getNumOperands())
-      OpRC = TII->getRegClass(*II, IIOpNum, TRI, *MF);
-
-    if (OpRC && !MRI->constrainRegClass(VReg, OpRC, MinRCSize)) {
-      assert(OpRC->isAllocatable() &&
-           "Constraining an allocatable VReg produced an unallocatable class?");
-
-      unsigned NewVReg = MRI->createVirtualRegister(OpRC);
+      DstRC = TRI->getAllocatableClass(TII->getRegClass(*II,IIOpNum,TRI,*MF));
+    if (DstRC && !MRI->constrainRegClass(VReg, DstRC, MinRCSize)) {
+      unsigned NewVReg = MRI->createVirtualRegister(DstRC);
       BuildMI(*MBB, InsertPos, Op.getNode()->getDebugLoc(),
               TII->get(TargetOpcode::COPY), NewVReg).addReg(VReg);
       VReg = NewVReg;

lib/Target/AMDGPU/SIRegisterInfo.cpp

@@ -79,6 +79,8 @@ unsigned SIRegisterInfo::getRegPressureSetLimit(const MachineFunction &MF,
                                           STI.getMaxWavesPerCU());
   unsigned VGPRLimit = getNumVGPRsAllowed(STI.getMaxWavesPerCU());
 
+  unsigned VSLimit = SGPRLimit + VGPRLimit;
+
   for (regclass_iterator I = regclass_begin(), E = regclass_end();
        I != E; ++I) {
     const TargetRegisterClass *RC = *I;
@@ -86,7 +88,11 @@ unsigned SIRegisterInfo::getRegPressureSetLimit(const MachineFunction &MF,
     unsigned NumSubRegs = std::max((int)RC->getSize() / 4, 1);
     unsigned Limit;
 
-    if (isSGPRClass(RC)) {
+    if (isPseudoRegClass(RC)) {
+      // FIXME: This is a hack. We should never be considering the pressure of
+      // these since no virtual register should ever have this class.
+      Limit = VSLimit;
+    } else if (isSGPRClass(RC)) {
       Limit = SGPRLimit / NumSubRegs;
     } else {
       Limit = VGPRLimit / NumSubRegs;

lib/Target/AMDGPU/SIRegisterInfo.h

@@ -59,6 +59,13 @@ public:
   /// \returns true if this class contains VGPR registers.
   bool hasVGPRs(const TargetRegisterClass *RC) const;
 
+  /// returns true if this is a pseudoregister class combination of VGPRs and
+  /// SGPRs for operand modeling. FIXME: We should set isAllocatable = 0 on
+  /// them.
+  static bool isPseudoRegClass(const TargetRegisterClass *RC) {
+    return RC == &AMDGPU::VS_32RegClass || RC == &AMDGPU::VS_64RegClass;
+  }
+
   /// \returns A VGPR reg class with the same width as \p SRC
   const TargetRegisterClass *getEquivalentVGPRClass(
                                           const TargetRegisterClass *SRC) const;

lib/Target/AMDGPU/SIRegisterInfo.td

@@ -272,12 +272,9 @@ def SCSrc_32 : RegInlineOperand<SReg_32> {
 //  VSrc_* Operands with an SGPR, VGPR or a 32-bit immediate
 //===----------------------------------------------------------------------===//
 
-def VS_32 : RegisterClass<"AMDGPU", [i32, f32], 32, (add SReg_32, VGPR_32)> {
-  let isAllocatable = 0;
-}
+def VS_32 : RegisterClass<"AMDGPU", [i32, f32], 32, (add VGPR_32, SReg_32)>;
 
-def VS_64 : RegisterClass<"AMDGPU", [i64, f64], 32, (add SReg_64, VReg_64)> {
-  let isAllocatable = 0;
+def VS_64 : RegisterClass<"AMDGPU", [i64, f64], 32, (add VReg_64, SReg_64)> {
   let CopyCost = 2;
 }
 

test/CodeGen/AMDGPU/ftrunc.f64.ll

@@ -27,8 +27,8 @@ define void @v_ftrunc_f64(double addrspace(1)* %out, double addrspace(1)* %in) {
 ; SI: s_and_b32 s{{[0-9]+}}, s{{[0-9]+}}, 0x80000000
 ; SI: s_add_i32 s{{[0-9]+}}, [[SEXP]], 0xfffffc01
 ; SI: s_lshr_b64
-; SI-DAG: s_not_b64
-; SI-DAG: s_and_b64
+; SI: s_not_b64
+; SI: s_and_b64
 ; SI-DAG: cmp_gt_i32
 ; SI-DAG: cndmask_b32
 ; SI-DAG: cndmask_b32

test/CodeGen/AMDGPU/llvm.round.f64.ll

@@ -21,7 +21,7 @@ define void @round_f64(double addrspace(1)* %out, double %x) #0 {
 ; SI-DAG: v_cmp_eq_i32
 
 ; SI-DAG: s_mov_b32 [[BFIMASK:s[0-9]+]], 0x7fffffff
-; SI-DAG: v_cmp_gt_i32
+; SI-DAG: v_cmp_gt_i32_e32
 ; SI-DAG: v_bfi_b32 [[COPYSIGN:v[0-9]+]], [[BFIMASK]]
 
 ; SI: buffer_store_dwordx2