From 1116868a0da41326eca5ecf8c9c7eb655effcac2 Mon Sep 17 00:00:00 2001
From: Venkatraman Govindaraju <venkatra@cs.wisc.edu>
Date: Sun, 24 Nov 2013 20:23:25 +0000
Subject: [Sparc] Emit large negative adjustments to SP/FP with sethi+xor
 instead of sethi+or. This generates correct code for both sparc32 and
 sparc64.

llvm-svn: 195576
---
 llvm/lib/Target/Sparc/SparcRegisterInfo.cpp | 41 ++++++++++++++++++++++++-----
 1 file changed, 34 insertions(+), 7 deletions(-)

(limited to 'llvm/lib/Target/Sparc/SparcRegisterInfo.cpp')

diff --git a/llvm/lib/Target/Sparc/SparcRegisterInfo.cpp b/llvm/lib/Target/Sparc/SparcRegisterInfo.cpp
index 9442d03c129..c98613aa120 100644
--- a/llvm/lib/Target/Sparc/SparcRegisterInfo.cpp
+++ b/llvm/lib/Target/Sparc/SparcRegisterInfo.cpp
@@ -105,19 +105,46 @@ static void replaceFI(MachineFunction &MF,
     // encode it.
     MI.getOperand(FIOperandNum).ChangeToRegister(FramePtr, false);
     MI.getOperand(FIOperandNum + 1).ChangeToImmediate(Offset);
-  } else {
-    // Otherwise, emit a G1 = SETHI %hi(offset).  FIXME: it would be better to
-    // scavenge a register here instead of reserving G1 all of the time.
-    const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
-    unsigned OffHi = (unsigned)Offset >> 10U;
-    BuildMI(*MI.getParent(), II, dl, TII.get(SP::SETHIi), SP::G1).addImm(OffHi);
+    return;
+  }
+
+  const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
+
+  // FIXME: it would be better to scavenge a register here instead of
+  // reserving G1 all of the time.
+  if (Offset >= 0) {
+    // Emit nonnegaive immediates with sethi + or.
+    // sethi %hi(Offset), %g1
+    // add %g1, %fp, %g1
+    // Insert G1+%lo(offset) into the user.
+    BuildMI(*MI.getParent(), II, dl, TII.get(SP::SETHIi), SP::G1)
+      .addImm(HI22(Offset));
+
+
     // Emit G1 = G1 + I6
     BuildMI(*MI.getParent(), II, dl, TII.get(SP::ADDrr), SP::G1).addReg(SP::G1)
       .addReg(FramePtr);
     // Insert: G1+%lo(offset) into the user.
     MI.getOperand(FIOperandNum).ChangeToRegister(SP::G1, false);
-    MI.getOperand(FIOperandNum + 1).ChangeToImmediate(Offset & ((1 << 10)-1));
+    MI.getOperand(FIOperandNum + 1).ChangeToImmediate(LO10(Offset));
+    return;
   }
+
+  // Emit Negative numbers with sethi + xor
+  // sethi %hix(Offset), %g1
+  // xor  %g1, %lox(offset), %g1
+  // add %g1, %fp, %g1
+  // Insert: G1 + 0 into the user.
+  BuildMI(*MI.getParent(), II, dl, TII.get(SP::SETHIi), SP::G1)
+    .addImm(HIX22(Offset));
+  BuildMI(*MI.getParent(), II, dl, TII.get(SP::XORri), SP::G1)
+    .addReg(SP::G1).addImm(LOX10(Offset));
+
+  BuildMI(*MI.getParent(), II, dl, TII.get(SP::ADDrr), SP::G1).addReg(SP::G1)
+    .addReg(FramePtr);
+  // Insert: G1+%lo(offset) into the user.
+  MI.getOperand(FIOperandNum).ChangeToRegister(SP::G1, false);
+  MI.getOperand(FIOperandNum + 1).ChangeToImmediate(0);
 }
 
 
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