[PATCH] D12296: AMDGPU: Make sure to reserve superregisters

[Matt Arsenault via llvm-commits]

arsenm created this revision.
arsenm added a reviewer: tstellarAMD.
arsenm added a subscriber: llvm-commits.
Herald added a subscriber: arsenm.

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

http://reviews.llvm.org/D12296

Files:
  lib/Target/AMDGPU/SIRegisterInfo.cpp
  lib/Target/AMDGPU/SIRegisterInfo.h

Index: lib/Target/AMDGPU/SIRegisterInfo.h
===================================================================
--- lib/Target/AMDGPU/SIRegisterInfo.h
+++ 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;
Index: lib/Target/AMDGPU/SIRegisterInfo.cpp
===================================================================
--- lib/Target/AMDGPU/SIRegisterInfo.cpp
+++ lib/Target/AMDGPU/SIRegisterInfo.cpp
@@ -26,23 +26,25 @@
 
 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 @@
 
     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);
     }
   }
 


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