SPARC v9 stack pointer bias.

64-bit SPARC v9 processes use biased stack and frame pointers, so the
current function's stack frame is located at %sp+BIAS .. %fp+BIAS where
BIAS = 2047.

This makes more local variables directly accessible via [%fp+simm13]
addressing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178965 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 9 insertions, 2 deletions

diff --git a/lib/Target/Sparc/SparcRegisterInfo.cpp b/lib/Target/Sparc/SparcRegisterInfo.cpp
index db9b30e..3af4c61 100644
--- a/lib/Target/Sparc/SparcRegisterInfo.cpp
+++ b/lib/Target/Sparc/SparcRegisterInfo.cpp
@@ -74,8 +74,9 @@ SparcRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
 
   // Addressable stack objects are accessed using neg. offsets from %fp
   MachineFunction &MF = *MI.getParent()->getParent();
-  int Offset = MF.getFrameInfo()->getObjectOffset(FrameIndex) +
-               MI.getOperand(FIOperandNum + 1).getImm();
+  int64_t Offset = MF.getFrameInfo()->getObjectOffset(FrameIndex) +
+                   MI.getOperand(FIOperandNum + 1).getImm() +
+                   Subtarget.getStackPointerBias();
 
   // Replace frame index with a frame pointer reference.
   if (Offset >= -4096 && Offset <= 4095) {
diff --git a/lib/Target/Sparc/SparcSubtarget.h b/lib/Target/Sparc/SparcSubtarget.h
index a81931b..b94dd11 100644
--- a/lib/Target/Sparc/SparcSubtarget.h
+++ b/lib/Target/Sparc/SparcSubtarget.h
@@ -52,6 +52,12 @@ public:
     }
     return std::string(p);
   }
+
+  /// The 64-bit ABI uses biased stack and frame pointers, so the stack frame
+  /// of the current function is the area from [%sp+BIAS] to [%fp+BIAS].
+  int64_t getStackPointerBias() const {
+    return is64Bit() ? 2047 : 0;
+  }
 };
 
 } // end namespace llvm