For Mips 16, add the optimization where the 16 bit form of addiu sp can be used

if the offset fits in 11 bits. This makes use of the fact that the abi
requires sp to be 8 byte aligned so the actual offset can fit in 8
bits. It will be shifted left and sign extended before being actually used.
The assembler or direct object emitter will shift right the 11 bit
signed field by 3 bits. We don't need to deal with that here.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175073 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 3 deletions

diff --git a/lib/Target/Mips/Mips16InstrInfo.cpp b/lib/Target/Mips/Mips16InstrInfo.cpp
index 9f27ac3517..5a91519fd8 100644
--- a/lib/Target/Mips/Mips16InstrInfo.cpp
+++ b/lib/Target/Mips/Mips16InstrInfo.cpp
@@ -184,7 +184,7 @@ void Mips16InstrInfo::makeFrame(unsigned SP, int64_t FrameSize,
       int64_t Remainder = FrameSize - Base;
       BuildMI(MBB, I, DL, get(Mips::SaveRaF16)). addImm(Base);
       if (isInt<16>(-Remainder))
-        BuildMI(MBB, I, DL, get(Mips::AddiuSpImmX16)). addImm(-Remainder);
+        BuildAddiuSpImm(MBB, I, DL, -Remainder);
       else
         adjustStackPtrBig(SP, -Remainder, MBB, I, Mips::V0, Mips::V1);
     }
@@ -225,7 +225,7 @@ void Mips16InstrInfo::restoreFrame(unsigned SP, int64_t FrameSize,
                        // returns largest possible n bit unsigned integer
       int64_t Remainder = FrameSize - Base;
       if (isInt<16>(Remainder))
-        BuildMI(MBB, I, DL, get(Mips::AddiuSpImmX16)). addImm(Remainder);
+        BuildAddiuSpImm(MBB, I, DL, Remainder);
       else
         adjustStackPtrBig(SP, Remainder, MBB, I, Mips::A0, Mips::A1);
       BuildMI(MBB, I, DL, get(Mips::RestoreRaF16)). addImm(Base);
@@ -299,7 +299,7 @@ void Mips16InstrInfo::adjustStackPtr(unsigned SP, int64_t Amount,
                                      MachineBasicBlock::iterator I) const {
   DebugLoc DL = I != MBB.end() ? I->getDebugLoc() : DebugLoc();
   if (isInt<16>(Amount))  // need to change to addiu sp, ....and isInt<16>
-    BuildMI(MBB, I, DL, get(Mips::AddiuSpImmX16)). addImm(Amount);
+    BuildAddiuSpImm(MBB, I, DL, Amount);
   else
     adjustStackPtrBigUnrestricted(SP, Amount, MBB, I);
 }
@@ -400,6 +400,15 @@ void Mips16InstrInfo::ExpandRetRA16(MachineBasicBlock &MBB,
   BuildMI(MBB, I, I->getDebugLoc(), get(Opc));
 }
 
+void Mips16InstrInfo::BuildAddiuSpImm(
+  MachineBasicBlock &MBB,
+  MachineBasicBlock::iterator II, DebugLoc DL, int64_t Imm) const {
+  if (validSpImm8(Imm))
+    BuildMI(MBB, II, DL, get(Mips::AddiuSpImm16)).addImm(Imm);
+  else
+    BuildMI(MBB, II, DL, get(Mips::AddiuSpImmX16)).addImm(Imm);
+}
+
 const MipsInstrInfo *llvm::createMips16InstrInfo(MipsTargetMachine &TM) {
   return new Mips16InstrInfo(TM);
 }