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Diffstat (limited to 'misc/pascal/insn16/doc/PascalOptimizations.txt')
| -rw-r--r-- | misc/pascal/insn16/doc/PascalOptimizations.txt | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/misc/pascal/insn16/doc/PascalOptimizations.txt b/misc/pascal/insn16/doc/PascalOptimizations.txt new file mode 100644 index 000000000..d197e73da --- /dev/null +++ b/misc/pascal/insn16/doc/PascalOptimizations.txt @@ -0,0 +1,239 @@ +P-Code optimizations: + Let <push-ops> be oPUSH|oPUSHB + Let <load-ops> be oLOD|oLODB|PUSH|oLADR|oLCADR + +pcopt.c:unaryOptimize +STEP 1: +Remove unary operators on constants: + <push-op> arg + oNEG -> <push-op> arg + <push-op> arg + oABS -> <push-op> |arg| + <push-op> arg + oINC -> <push-op> arg+1 + <push-op> arg + oDEC -> <push-op> arg-1 + <push-op> arg + oNOT -> <push-op> ~arg + +Simplify binary operations on constants + <push-op> arg + oADD + if arg == 0 -> delete both + else if arg == 1 -> oINC + else if arg == -1 -> oDEC + <push-op> arg + oSUB + if arg == 0 -> delete both + else if arg == 1 -> oDEC + else if arg == -1 -> oINC + <push-op> arg + oMUL + if arg is power of 2 -> oSLL power + <push-op> arg + oDIV + if arg is power of 2 -> oSRA power + <push-op> arg + oSLL + if arg is 0 -> <push-op> arg + <push-op> arg + oSRL + if arg is 0 -> <push-op> arg + <push-op> arg + oSRA + if arg is 0 -> <push-op> arg + <push-op> arg + oOR + if arg is 0 -> <push-op> arg + <push-op> arg + oAND + if arg is 0xffff -> <push-op> arg + +Delete comparisons with zero + <push-op> arg + oEQUZ + if arg == 0 -> <push-op> true + else -> <push-op> false + <push-op> arg + oNEQZ + if arg != 0 -> <push-op> true + else -> <push-op> false + <push-op> arg + oLTZ + if arg < 0 -> <push-op> true + else -> <push-op> false + <push-op> arg + oGTEZ + if arg >= 0 -> <push-op> true + else -> <push-op> false + <push-op> arg + oGTZ + if arg > 0 -> <push-op> true + else -> <push-op> false + <push-op> arg + oLTEZ + if arg <= 0 -> <push-op> true + else -> <push-op> false + +Simplify comparisons with certain constants + <push-op> arg + oEQU + if arg == 0 -> oEQUZ + else if arg == 1 -> oDEC + oEQUZ + else if arg == -1 -> oINC + oEQUZ + <push-op> arg + oNEQ + if arg == 0 -> oNEQZ + else if arg == 1 -> oDEC + oNEQZ + else if arg == -1 -> oINC + oNEQZ + <push-op> arg + oLT + if arg == 0 -> oLTZ + else if arg == 1 -> oDEC + oLTZ + else if arg == -1 -> oINC + oLTZ + <push-op> arg + oGTE + if arg == 0 -> oGTEZ + else if arg == 1 -> oDEC + oGTEZ + else if arg == -1 -> oINC + oGTEZ + <push-op> arg + oGT + if arg == 0 -> oGTZ + else if arg == 1 -> oDEC + oGTZ + else if arg == -1 -> oINC + oGTZ + <push-op> arg + oLTE + if arg == 0 -> oLTEZ + else if arg == 1 -> oDEC + oLTEZ + else if arg == -1 -> oINC + oLTEZ + +Simplify or delete condition branches on constants + <push-op> arg + oJEQUZ + if arg == 0 -> oJMP + else -> delete both + <push-op> arg + oJNEQZ + if arg != 0 -> oJMP + else -> delete both + <push-op> arg + oJLTZ + if arg < 0 -> oJMP + else -> delete both + <push-op> arg + oJGTEZ + if arg >= 0 -> oJMP + else -> delete both + <push-op> arg + oJGTZ + if arg > 0 -> oJMP + else -> delete both + <push-op> arg + oJLTEZ + if arg <= 0 -> oJMP + else -> delete both +STEP 1a: + <push-op> arg + if arg < 256 -> oPUSHB arg + else -> oPUSH arg + +STEP 2: +Delete multiple modifications of DSEG pointer + INDS arg1 + INDS arg2 -> INDS arg1+arg2 + +pcopt.c:binaryOptimize +STEP 1: + <push-op> arg1 + <push-op> arg2 + oADD -> oPUSH arg1 + arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oSUB -> oPUSH arg1 - arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oMUL -> oPUSH arg1 * arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oDIV -> oPUSH arg1 / arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oMOD -> oPUSH arg1 % arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oSLL -> oPUSH arg1 << arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oSRL -> oPUSH arg1 >> arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oSRA -> oPUSH arg1 >> arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oOR -> oPUSH arg1 | arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oAND -> oPUSH arg1 & arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oEQU -> oPUSH arg1 == arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oNEQ -> oPUSH arg1 != arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oLT -> oPUSH arg1 < arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oGTE -> oPUSH arg1 >= arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oGT -> oPUSH arg1 > arg2 + STEP 1a + <push-op> arg1 + <push-op> arg2 + oLTE -> oPUSH arg1 <= arg2 + STEP 1a +STEP 1a: + <push-op> arg + if arg < 256 -> oPUSHB arg + else -> oPUSH arg + +STEP 2: + <push-op> arg1 + <load-ops> arg2 + oADD + if arg1 == 0 -> <load-ops> arg + else if arg1 == 1 -> <load-ops> arg + oINC + else if arg1 == -1 -> <load-ops> arg + oDEC + <push-op> arg1 + <load-ops> arg2 + oSUB + if arg1 == 0 -> <load-ops> arg + oNEG + <push-op> arg1 + <load-ops> arg2 + oMUL -> <load-ops> arg + oSLL log + if arg is a power of 2 + <push-op> arg1 + <load-ops> arg2 + oOR + if arg1 == 0 -> <load-ops> arg + <push-op> arg1 + <load-ops> arg2 + oAND + if arg1 == 0xffff -> <load-ops> arg + <push-op> arg1 + <load-ops> arg2 + oEQU + if arg1 == 0 -> <load-ops> arg + oEQUZ + <push-op> arg1 + <load-ops> arg2 + oNEQ + if arg1 == 0 -> <load-ops> arg + oNEQZ + <push-op> arg1 + <load-ops> arg2 + oLT + if arg1 == 0 -> <load-ops> arg + oLTZ + <push-op> arg1 + <load-ops> arg2 + oGTE + if arg1 == 0 -> <load-ops> arg + oGTEZ + <push-op> arg1 + <load-ops> arg2 + oGT + if arg1 == 0 -> <load-ops> arg + oGTZ + <push-op> arg1 + <load-ops> arg2 + oLTE + if arg1 == 0 -> <load-ops> arg + oLTEZ + +STEP 2a: + if the <push-op> op is still there + <push-op> arg + if arg < 256 -> oPUSHB arg + else -> oPUSH arg + +STEP 3 + oNEG + oADD -> oSUB + oNEG + oSUB -> oADD + +pjopt.c: BranchOptimize + oNOT + oJEQUZ -> oJNEQZ + oNOT + oJNEQZ -> oJEQUZ + oNEG + oJLTZ -> oJGTZ + oNEG + oJGTEZ -> oJLTEZ + oNEG + oJGTZ -> oJLTZ + oNEG + oJLTEZ -> oJGTEZ + oEQU + oNOT -> oNEQ + oEQU + oJEQUZ -> oJNEQ + oEQU + oJNEQZ -> oJEQU + oNEQ + oNOT -> oEQU + oNEQ + oJEQUZ -> oJEQU + oNEQ + oJNEQZ -> oJNEQ + oLT + oNOT -> oGTE + oLT + oJEQUZ -> oJGTE + oLT + oJNEQZ -> oJLT + oGTE + oNOT -> oLT + oGTE + oJEQUZ -> oJLT + oGTE + oJNEQZ -> oJGTE + oGT + oNOT -> oLTE + oGT + oJEQUZ -> oJLTE + oGT + oJNEQZ -> oJGT + oLTE + oJNOT -> oGT + oLTE + oJEQUZ -> oJGT + oLTE + oJNEQZ -> oJLTE + oEQUZ + oNOT -> oNEQZ + oEQUZ + oJEQUZ -> oJNEQZ + oEQUZ + oJNEQZ -> oJEQUZ + oNEQZ + oNOT -> oEQUZ + oNEQZ + oJEQUZ -> oJEQUZ + oNEQZ + oJNEQZ -> oJNEQZ + oLTZ + oNOT -> oGTEZ + oLTZ + oJEQUZ -> oJGTEZ + oLTZ + oJNEQZ -> oJLTZ + oGTEZ + oNOT -> oLTZ + oGTEZ + oJEQUZ -> oJLTZ + oGTEZ + oJNEQZ -> oJGTEZ + oGTZ + oNOT -> oLTEZ + oGTZ + oJEQUZ -> oJLTEZ + oGTZ + oJNEQZ -> oJGTZ + oLTEZ + oNOT -> oGTZ + oLTEZ + oJEQUZ -> oJGTZ + oLTEZ + oJNEQZ -> oJLTEZ + +plopt.c:LoadOptimize() +Eliminate duplicate loads + oLOD arg1 + oLOAD arg1 -> oLOD arg1 + oDUP + +Convert loads indexed by a constant to unindexed loads +!!! DISABLED !!! Does not work because arg2 is a label, not an address !!! + <push-op> arg1 + oLODX arg2 -> oLOD arg1 + arg2 + <push-op> arg1 + oLADRX arg2 -> oLADR arg1 + arg2 + <push-op> arg1 + oLODBX arg2 -> oLODB arg1 + arg2 + <push-op> arg1 + oLODMX arg2 -> oLODM arg1 + arg2 + <push-op> arg + if arg < 256 -> oPUSHB arg + +plopt.c:StoreOptimize() +Eliminate store followed by load + oSTO arg + oLOAD arg -> oSTO arg + oDUP + +Convert stores indexed by a constant to unindexed stores + <push-op> arg1 + ? + oSTOX arg2 -> ? + oSTO arg1 + arg2 + <push-op> arg1 + ? + oSTOBX arg2 -> ? + oSTOB arg1 + arg2 + +Missing local optimization: + +Need to check for branches (conditional or unconditional) to the +next instruction. |