add L8.pdf and complement in 11.06

notes/7.md

@@ -17,12 +17,10 @@ Keep the top of the stack in a register, so `add` requires only a single memory
 * `pop`
 * `add`
 
-
 ### Code Generation From Stack Machine
 
 Assume that stack grows towards lower addresses.
 
-
 ## MIPS
 
 32 regs
@@ -36,7 +34,6 @@ Assume that stack grows towards lower addresses.
 * `li`
 * `mv`
 
-
 Converting Stack to MIPS ISA
 
 * `acc <- i`
@@ -44,13 +41,56 @@ Converting Stack to MIPS ISA
 
 ### Optimizing
 
-
+no
 
 ## Branch
 
 `beq $1 $2 lbl`
 `b lbl`
 
-
 ## Function
 
+At Caller Side:
+1. saves the `$fp` to the stack
+2. saves the actual params in reverse order
+3. saves the return address to `$ra`
+
+At Callee Side:
+1. set `$fp` to `$sp`
+2. the callee saves the return address
+3. ...
+
+## Temp Var
+
+Many various intermediate vars should be stored in the AR. But compiler can statically know how many temporary variables there are.
+
+Let $NT(e)$ is defined recursively by:
+$$NT(e1 + e2) = \max (NT(e1), NT(e2) + 1)$$
+
+for example:
+
+### CG using NT
+
+add new args to the `cgen(e, nt)`
+
+reduce number of decrease `$sp` (`addi $sp $sp -4`)
+
+
+## Intermediate Representation (IR)
+
+Before:
+Each Languages need respective, different Optimizer.
+
+Now:
+Common IR optimizer.
+
+
+IR is language-independent and machine-independent optimization.
+
+### High-Level Assembly
+
+It uses unlimited number of registers.
+It uses assembly-like control structures (jmp and lbl).
+opcodes but some are higher level
+
+igen(e, t)