Changeset 4864

Timestamp:

Nov 10, 2015, 7:44:20 AM (3 years ago)

Author:

cameron

Message:

Eliminate trivial reassignments

File:

• proto/pabloH/pabloc1.hs (modified) (3 diffs)

proto/pabloH/pabloc1.hs

@@ -5 +5 @@
 import System.IO (stdout,stderr,hPutStr,hPutStrLn)
 import Control.Monad
-
 
 compileBinary :: (String, Int, PabloE, PabloE, Operator) -> (Int, [PabloInstruction], Operand)
@@ -40 +39 @@
         IRvar(t4))
 
+replaceOrAssignTarget(targetVar, (n, [], v)) = (n, [IRassign(targetVar, v)])
+replaceOrAssignTarget(targetVar, (n, instrs, v)) = 
+    case (last instrs) of
+        Binary(temp, op, e1, e2) -> (n-1, (init instrs) ++ [Binary(targetVar, op, e1, e2)])
+        _ -> (n, instrs ++ [IRassign(targetVar, v)])
+
 compileAssigns :: (String, Int, [PabloS]) -> (Int, [PabloInstruction])
 compileAssigns (pfx, n, []) = (n, [])
 compileAssigns (pfx, n, Assign(varname, e) : more) = 
-   let (n1, instrs, v) = compileE(pfx, n, e)
+   let (n1, instrs) = replaceOrAssignTarget(varname, compileE(pfx, n, e))
        (n2, moreInstrs) = compileAssigns(pfx, n1, more)
-   in (n2, instrs ++ (IRassign(varname, v) : moreInstrs))
+   in (n2, instrs ++ moreInstrs)
 
 isAssign (Assign(v,e)) = True
@@ -76 +81 @@
               in (n4, block1 : block2 : (repeatIR ++ afterIR))
       
-      
 compileMain stmts = 
     let (n, compiled) = compileStmts("tmp", 0, "entry", Ret, stmts)