Implement if statements with equality

lib/Language/Elna/RiscV/CodeGenerator.hs

@@ -13,7 +13,7 @@ import Data.Vector (Vector)
 import qualified Data.Vector as Vector
 import qualified Language.Elna.Architecture.RiscV as RiscV
 import Language.Elna.Backend.Allocator (MachineConfiguration(..), Store(..))
-import Language.Elna.Backend.Intermediate (Operand(..), Quadruple(..))
+import Language.Elna.Backend.Intermediate (Label(..), Operand(..), Quadruple(..))
 import Language.Elna.Location (Identifier(..))
 import Data.Bits (Bits(..))
 import Data.Foldable (Foldable(..), foldlM)
@@ -45,6 +45,10 @@ riscVConfiguration = MachineConfiguration
         ]
     }
 
+-- | Reserved register used for calculations to save an immediate temporary.
+immediateRegister :: RiscV.XRegister
+immediateRegister = RiscV.A7
+
 type RiscVStore = Store RiscV.XRegister
 type RiscVQuadruple = Quadruple RiscVStore
 type RiscVOperand = Operand RiscVStore
@@ -243,6 +247,43 @@ quadruple (DivisionQuadruple operand1 operand2 (Store register))
             $ RiscV.BaseInstruction RiscV.Op
             $ RiscV.R register RiscV.DIV register operandRegister2
             $ RiscV.Funct7 0b0000001
+quadruple (LabelQuadruple (Label label)) = pure $ Vector.singleton $ JumpLabel label mempty
+quadruple (GoToQuadruple label) = pure $ Vector.singleton $ unconditionalJal label
+quadruple (EqualQuadruple operand1 operand2 goToLabel)
+    | IntOperand immediateOperand1 <- operand1
+    , IntOperand immediateOperand2 <- operand2 =
+        if immediateOperand1 == immediateOperand2
+        then pure $ Vector.singleton $ unconditionalJal goToLabel
+        else pure Vector.empty
+    | VariableOperand variableOperand1 <- operand1
+    , VariableOperand variableOperand2 <- operand2 = do
+        let Store operandRegister1 = variableOperand1
+            Store operandRegister2 = variableOperand2
+        branchLabel <- createLabel
+        pure $ Vector.singleton
+            $ Instruction
+            $ RiscV.RelocatableInstruction RiscV.Branch
+            $ RiscV.RBranch branchLabel RiscV.BEQ operandRegister1 operandRegister2
+    | VariableOperand variableOperand1 <- operand1
+    , IntOperand immediateOperand2 <- operand2 =
+        compareImmediateRegister variableOperand1 immediateOperand2
+    | IntOperand immediateOperand1 <- operand1
+    , VariableOperand variableOperand2 <- operand2 =
+        compareImmediateRegister variableOperand2 immediateOperand1
+  where
+    compareImmediateRegister variableOperand immediateOperand = 
+        let statements = lui immediateOperand immediateRegister
+            Store operandRegister = variableOperand
+            Label goToLabel' = goToLabel
+        in pure $ Vector.snoc statements
+            $ Instruction
+            $ RiscV.RelocatableInstruction RiscV.Branch
+            $ RiscV.RBranch goToLabel' RiscV.BEQ operandRegister immediateRegister
+
+unconditionalJal :: Label -> Statement
+unconditionalJal (Label goToLabel) = Instruction
+    $ RiscV.RelocatableInstruction RiscV.Jal
+    $ RiscV.RJal RiscV.Zero goToLabel
 
 loadImmediateOrRegister :: RiscVOperand -> RiscV.XRegister -> (RiscV.XRegister, Vector Statement)
 loadImmediateOrRegister (IntOperand intValue) targetRegister =

lib/Language/Elna/RiscV/ElfWriter.hs

@@ -236,8 +236,8 @@ riscv32Elf code objectHandle = text
                             , st_info = stInfo STB_GLOBAL STT_FUNC
                             }
                         result =
-                            ( encoded <> encoded'
-                            , relocations <> relocations'
+                            ( encoded'
+                            , relocations'
                             , ElfHeaderResult (names <> Text.encodeUtf8 labelName <> "\0") (Vector.snoc symbols newEntry)
                             , definitions'
                             )
@@ -260,6 +260,9 @@ riscv32Elf code objectHandle = text
                         | RiscV.RBranch symbolName _ _ _ <- instructionType
                             -> Just -- R_RISCV_BRANCH
                             $ UnresolvedRelocation (Text.encodeUtf8 symbolName) offset 16
+                        | RiscV.RJal _ symbolName <- instructionType
+                            -> Just -- R_RISCV_JAL
+                            $ UnresolvedRelocation (Text.encodeUtf8 symbolName) offset 17
                     RiscV.CallInstruction symbolName
                         -> Just -- R_RISCV_CALL_PLT
                         $ UnresolvedRelocation (Text.encodeUtf8 symbolName) offset 19