[MIPS GlobalISel] Select zero extending and sign extending load

Select zero extending and sign extending load for MIPS32.
Use size from MachineMemOperand to determine number of bytes to load.

Differential Revision: https://reviews.llvm.org/D57099

llvm-svn: 352038

1 files changed, 30 insertions, 2 deletions

diff --git a/llvm/lib/Target/Mips/MipsInstructionSelector.cpp b/llvm/lib/Target/Mips/MipsInstructionSelector.cpp
index 37d7767085a..eb8c919d38c 100644
--- a/llvm/lib/Target/Mips/MipsInstructionSelector.cpp
+++ b/llvm/lib/Target/Mips/MipsInstructionSelector.cpp
@@ -90,6 +90,28 @@ static bool selectCopy(MachineInstr &I, const TargetInstrInfo &TII,
   return true;
 }
 
+/// Returning Opc indicates that we failed to select MIPS instruction opcode.
+static unsigned selectLoadStoreOpCode(unsigned Opc, unsigned MemSizeInBytes) {
+  if (Opc == TargetOpcode::G_STORE)
+    switch (MemSizeInBytes) {
+    case 4:
+      return Mips::SW;
+    default:
+      return Opc;
+    }
+  else
+    switch (MemSizeInBytes) {
+    case 4:
+      return Mips::LW;
+    case 2:
+      return Opc == TargetOpcode::G_SEXTLOAD ? Mips::LH : Mips::LHu;
+    case 1:
+      return Opc == TargetOpcode::G_SEXTLOAD ? Mips::LB : Mips::LBu;
+    default:
+      return Opc;
+    }
+}
+
 bool MipsInstructionSelector::select(MachineInstr &I,
                                      CodeGenCoverage &CoverageInfo) const {
 
@@ -127,15 +149,21 @@ bool MipsInstructionSelector::select(MachineInstr &I,
     break;
   }
   case G_STORE:
-  case G_LOAD: {
+  case G_LOAD:
+  case G_ZEXTLOAD:
+  case G_SEXTLOAD: {
     const unsigned DestReg = I.getOperand(0).getReg();
     const unsigned DestRegBank = RBI.getRegBank(DestReg, MRI, TRI)->getID();
     const unsigned OpSize = MRI.getType(DestReg).getSizeInBits();
+    const unsigned OpMemSizeInBytes = (*I.memoperands_begin())->getSize();
 
     if (DestRegBank != Mips::GPRBRegBankID || OpSize != 32)
       return false;
 
-    const unsigned NewOpc = I.getOpcode() == G_STORE ? Mips::SW : Mips::LW;
+    const unsigned NewOpc =
+        selectLoadStoreOpCode(I.getOpcode(), OpMemSizeInBytes);
+    if (NewOpc == I.getOpcode())
+      return false;
 
     MI = BuildMI(MBB, I, I.getDebugLoc(), TII.get(NewOpc))
              .add(I.getOperand(0))