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Diffstat (limited to 'docs/chapter14')
| -rw-r--r-- | docs/chapter14/14-grammar.md | 124 | ||||
| -rw-r--r-- | docs/chapter14/Makefile | 12 | ||||
| -rw-r--r-- | docs/chapter14/README.md | 85 |
3 files changed, 221 insertions, 0 deletions
diff --git a/docs/chapter14/14-grammar.md b/docs/chapter14/14-grammar.md new file mode 100644 index 00000000..a6d4df42 --- /dev/null +++ b/docs/chapter14/14-grammar.md @@ -0,0 +1,124 @@ +# Grammar for Chapter 14 + +```antlrv4 +grammar SimpleLanguage; + +program : block EOF ; + +block : statement+ ; + + +statement + : '{' block '}' + | returnStatement + | ifStatement + | whileStatement + | breakStatement + | continueStatement + | metaStatement + | structDeclaration + | expressionStatement + ; + + +returnStatement : 'return' expression ';' ; + +ifStatement : 'if' '(' expression ')' statement ('else' statement)? ; + +whileStatement : 'while' '(' expression ')' statement ; + +breakStatement : 'break' ';' ; + +continueStatement : 'continue' ';' ; + +metaStatement : '#showGraph' ';' ; + +structDeclaration : 'struct' IDENTIFIER '{' fields '}' ; + +fields : field+ ; + +field : type IDENTIFIER ';' ; + + +expressionStatement + : type IDENTIFIER ';' + | type IDENTIFIER '=' expression ';' + | IDENTIFIER '=' expression ';' + | expression + ; + +PRIMTYPE + : 'int' + | 'i8' + | 'i16' + | 'i32' + | 'i64' + | 'u8' + | 'u16' + | 'u32' + | 'flt' + | 'f32' + | 'f64' + | 'bool' + ; + +type + : PRIMTYPE + | typeName ('?')? + ; + +typeName : IDENTIFIER ; + + +expression : bitWiseExpression ; + +bitWiseExpression + : comparisonExpression ( '&' | '|' | '^' ) comparisonExpression)* + ; + +comparisonExpression + : shiftExpression (('==' | '!='| '>'| '<'| '>='| '<=') shiftExpression)* + ; + +shiftExpression + : additiveExpression ( '<<' | '>>>' | '>>' ) additiveExpression)* + ; + +additiveExpression + : multiplicativeExpression (('+' | '-') multiplicativeExpression)* + ; + +multiplicativeExpression + : unaryExpression (('*' | '/') unaryExpression)* + ; + +unaryExpression + : ('-') unaryExpression + | '!' unaryExpression + | primaryExpression postFix* + ; + +primaryExpression + : INTEGER_LITERAL + | '(' expression ')' + | 'true' + | 'false' + | 'null' + | newExpression + | IDENTIFIER + ; + +newExpression : 'new' IDENTIFIER ; + +postFix : '.' IDENTIFIER [ '=' expression ] ; + +INTEGER_LITERAL + : [1-9]DIGIT* + | [0] + ; + +IDENTIFIER : NON_DIGIT (NON_DIGIT | DIGIT)* ; + +NON_DIGIT: [a-zA-Z_]; +DIGIT: [0-9]; +``` diff --git a/docs/chapter14/Makefile b/docs/chapter14/Makefile new file mode 100644 index 00000000..12659b8f --- /dev/null +++ b/docs/chapter14/Makefile @@ -0,0 +1,12 @@ +GV := $(wildcard *.gv) +SVG := $(patsubst %.gv,%.svg,$(GV)) + +.PHONY: all +all: $(SVG) + +%.svg: %.gv + dot -Tsvg $< > $@ + +.PHONY: clean +clean: + @rm -f $(SVG) diff --git a/docs/chapter14/README.md b/docs/chapter14/README.md new file mode 100644 index 00000000..8451c4f5 --- /dev/null +++ b/docs/chapter14/README.md @@ -0,0 +1,85 @@ +# Chapter 14: Narrow types + +In this chapter, we add sub-word integer types. + +You can also read [this chapter](https://github.com/SeaOfNodes/Simple/tree/linear-chapter14) in a linear Git revision history on the [linear](https://github.com/SeaOfNodes/Simple/tree/linear) branch and [compare](https://github.com/SeaOfNodes/Simple/compare/linear-chapter13...linear-chapter14) it to the previous chapter. + +## Narrow or sub-word types + +As a prelude to arrays, especially arrays of bytes common in all networking +codes, Simple needs some way to manipulate sub-word integer types. +Computations are always done in 64 bits for both integer and float ops, but +will be truncated (rounded) on a variable or field assignment, and (sign) +extended on a load. + +```java +i8 x = 123456789; +if( x != 21 ) + return false; +return true; +``` + +The variable `x` is limited to 8 bits signed. Assigning the vary large value +`123456789` (hex `0x75BCD15`) simply truncates to 8 bits yielding `21 (0x15)`. +The value is sign-extended on a load. + +```java +i16 x = 123456789; +if( x != -13035 ) + return false; +return true; +``` + +The variable `x` is limited to 16 bits signed. Assigning the vary large value +`0x75BCD15` simply truncates to 16 bits yielding `0xCD15`. The value is +sign-extended on a load yielding `-13035 (0xFFFF FFFF FFFF CD15)`. + +```java +u16 x = 123456789; +if( x != 52501 ) + return false; +return true; +``` + +The variable `x` is limited to 16 bits unsigned. Assigning the vary large value +`0x75BCD15` simply truncates to 16 bits yielding `0xCD15`. The value is +zero-extended on a load yielding `52501 (0x0000 0000 0000 CD15)`. + +Similarly, floats can be limited to IEEE754 32-bit standard format and will be +rounded when assigned, and inflated to 64-bits when loaded. + +The complete list of primitive types is now: +```java +int, i64 // 64-bits, matching modern hardware +// u64 // NOT implemented, as it hints at some kind of >64 bit behavior +i32, u32 // 32 bits, sign or zero extended on load +i16, u16 // 16 bits, sign or zero extended on load + i8, u8 // 8 bits, sign or zero extended on load + i1, u1 // 1 bit , sign or zero extended on load +bool // Same as u1 +flt, f64 // IEEE 754 64-bit float, sometimes called a "double" +f32 // IEEE 754 32-bit float +``` + + + +## Type Implementation + +The TypeInteger class is reworked to support a full range of min/max values. +At this time, only some power-of-2 sized ranges are exposed but the optimizer +internally supports all ranges. The MEET operation takes the min-of-mins and +max-of-maxes. The DUAL operation inverts the min and max. + +The TypeFloat class is also reworked to support 32-bit and 64-bit sizes. + + +## Nodes + +Added this Chapter are some bit-manipulation Nodes representing common hardware +ops to mask, shift, sign-extend and round bits. The truncation and extension +logic uses these. They are otherwise very similar to the previous +`Add/Sub/Mul/Div` Nodes but with slightly different constant math and +slightly different `idealize()` calls. + + + |
