Merging r246051:

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r246051 | Matthew.Arsenault | 2015-08-26 14:54:50 -0400 (Wed, 26 Aug 2015) | 6 lines

AMDGPU: Make sure to reserve super registers

I think this could potentially have broken if
one of the super registers were allocated
that contain v254/v255.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_37@253235 91177308-0d34-0410-b5e6-96231b3b80d8

Author: tstellarAMD

lib/Target/AMDGPU/SIRegisterInfo.cpp

@@ -26,23 +26,25 @@ using namespace llvm;
 
 SIRegisterInfo::SIRegisterInfo() : AMDGPURegisterInfo() {}
 
-BitVector SIRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
-  BitVector Reserved(getNumRegs());
-  Reserved.set(AMDGPU::EXEC);
+void SIRegisterInfo::reserveRegisterTuples(BitVector &Reserved, unsigned Reg) const {
+  MCRegAliasIterator R(Reg, this, true);
 
-  // EXEC_LO and EXEC_HI could be allocated and used as regular register,
-  // but this seems likely to result in bugs, so I'm marking them as reserved.
-  Reserved.set(AMDGPU::EXEC_LO);
-  Reserved.set(AMDGPU::EXEC_HI);
+  for (; R.isValid(); ++R)
+    Reserved.set(*R);
+}
 
+BitVector SIRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
+  BitVector Reserved(getNumRegs());
   Reserved.set(AMDGPU::INDIRECT_BASE_ADDR);
-  Reserved.set(AMDGPU::FLAT_SCR);
-  Reserved.set(AMDGPU::FLAT_SCR_LO);
-  Reserved.set(AMDGPU::FLAT_SCR_HI);
+
+  // EXEC_LO and EXEC_HI could be allocated and used as regular register, but
+  // this seems likely to result in bugs, so I'm marking them as reserved.
+  reserveRegisterTuples(Reserved, AMDGPU::EXEC);
+  reserveRegisterTuples(Reserved, AMDGPU::FLAT_SCR);
 
   // Reserve some VGPRs to use as temp registers in case we have to spill VGPRs
-  Reserved.set(AMDGPU::VGPR255);
-  Reserved.set(AMDGPU::VGPR254);
+  reserveRegisterTuples(Reserved, AMDGPU::VGPR254);
+  reserveRegisterTuples(Reserved, AMDGPU::VGPR255);
 
   // Tonga and Iceland can only allocate a fixed number of SGPRs due
   // to a hw bug.
@@ -54,10 +56,7 @@ BitVector SIRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
 
     for (unsigned i = Limit; i < NumSGPRs; ++i) {
       unsigned Reg = AMDGPU::SGPR_32RegClass.getRegister(i);
-      MCRegAliasIterator R = MCRegAliasIterator(Reg, this, true);
-
-      for (; R.isValid(); ++R)
-        Reserved.set(*R);
+      reserveRegisterTuples(Reserved, Reg);
     }
   }
 

lib/Target/AMDGPU/SIRegisterInfo.h

@@ -23,7 +23,10 @@
 namespace llvm {
 
 struct SIRegisterInfo : public AMDGPURegisterInfo {
+private:
+  void reserveRegisterTuples(BitVector &, unsigned Reg) const;
 
+public:
   SIRegisterInfo();
 
   BitVector getReservedRegs(const MachineFunction &MF) const override;