## Mu's instructions and their table-driven translation
Mu is a statement-oriented language. Blocks consist of flat lists of instructions.
The chart at the bottom of this page shows all the instruction forms supported
by Mu, one to a line. Each line shows an example of the instruction on the
left. Past the first column, everything inside the {..} is a summary of the
data structure the Mu compiler uses (`Primitives` in apps/mu.subx) to translate
it.
The syntax of the data structure is intended to be similar to C++'s aggregate
initializers (https://en.cppreference.com/w/cpp/language/aggregate_initialization)
However, there are differences:
- We use adjacency for string concatenation.
- We use [] for array literals.
- The objects inside [] are not fully described. They include various
metadata about the variable in the instruction. For our purposes, assume
that variables on the stack have a stack offset computed for them, and
register variables evaluate to their register.
- registers may be specified by name: /eax /ecx /edx /ebx /esi /edi
- registers may be specified as a wildcard: /reg
- integer literals are always called 'n'
- any other variable names that don't specify a register are assumed to be on the stack
There are no checks for types yet, because Mu programs only have `int` types so far.
Example 1 (use the widest screen you can for this page):
-- instruction form -- | -------------------------- data structure ----------------------------
|<------------- pattern matching ---------->|<--- code generation ------------------->
var/reg <- add var2/reg {.name="add", .inouts=[reg], .outputs=[reg], .subx-name="01/add<-", .rm32=outputs[0], .r32=inouts[0]}
Read this as:
if an instruction's name is "add"
and it has one inout that's in a register
and it has one output that's in a register,
then emit the following on a single line
"01/add<-" (the opcode or subx-name)
"%{reg}", interpolating the output's register
"{reg}/r32", interpolating the inout's register code.
Example 2:
-- instruction form -- | -------------------------- data structure ----------------------------
|<------- pattern matching ------>|<--- code generation ------------------->
add-to var, n {.name="add-to", .inouts=[var, n], .subx-name="81 0/subop/add", .rm32="*(ebp+" inouts[0].stack-offset ")", .imm32=inouts[1]}
Read this as:
if an instruction's name is "add-to"
and it has two inouts
the first on the stack
and the second a literal,
then emit the following on a single line
"81 0/subop/add" (the opcode or subx-name)
"*(ebp+{stack})", interpolating the first inout's stack offset
"{n}/imm32", interpolating the second inout's contents
Ok, here's the complete chart.
-- instruction form -- | -------------------------- data structure ----------------------------
|<------------------- pattern matching ------------------->|<---- code generation ------------------->
var/eax <- increment {.name="increment", .outputs=[eax], .subx-name="40/increment-eax"}
var/ecx <- increment {.name="increment", .outputs=[ecx], .subx-name="41/increment-ecx"}
var/edx <- increment {.name="increment", .outputs=[edx], .subx-name="42/increment-edx"}
var/ebx <- increment {.name="increment", .outputs=[ebx], .subx-name="43/increment-ebx"}
var/esi <- increment {.name="increment", .outputs=[esi], .subx-name="46/increment-esi"}
var/edi <- increment {.name="increment", .outputs=[edi], .subx-name="47/increment-edi"}
increment var {.name="increment", .inouts=[var], .subx-name="ff 0/subop/increment", .rm32="*(ebp+" inouts[0].stack-offset ")"}
var/eax <- decrement {.name="decrement", .outputs=[eax], .subx-name="48/decrement-eax"}
var/ecx <- decrement {.name="decrement", .outputs=[ecx], .subx-name="49/decrement-ecx"}
var/edx <- decrement {.name="decrement", .outputs=[edx], .subx-name="4a/decrement-edx"}
var/ebx <- decrement {.name="decrement", .outputs=[ebx], .subx-name="4b/decrement-ebx"}
var/esi <- decrement {.name="decrement", .outputs=[esi], .subx-name="4e/decrement-esi"}
var/edi <- decrement {.name="decrement", .outputs=[edi], .subx-name="4f/decrement-edi"}
decrement var {.name="decrement", .inouts=[var], .subx-name="ff 1/subop/decrement", .rm32="*(ebp+" inouts[0].stack-offset ")"}
var1/reg1 <- add var2/reg2 {.name="add", .inouts=[reg2], .outputs=[reg1], .subx-name="01/add<-", .rm32=outputs[0], .r32=inouts[0]}
var/reg <- add var2 {.name="add", .inouts=[var2], .outputs=[reg], .subx-name="03/add->", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=outputs[0]}
add-to var1, var2/reg {.name="add-to", .inouts=[var1, var2], .subx-name="01/add<-", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=inouts[1]}
var/eax <- add n {.name="add", .inouts=[n], .outputs=[eax], .subx-name="05/add-to-eax", .imm32=inouts[0]}
var/reg <- add n {.name="add", .inouts=[n], .outputs=[reg], .subx-name="81 0/subop/add", .rm32=outputs[0], .imm32=inouts[0]}
add-to var, n {.name="add-to", .inouts=[var, n], .subx-name="81 0/subop/add", .rm32="*(ebp+" inouts[0].stack-offset ")", .imm32=inouts[1]}
var1/reg1 <- sub var2/reg2 {.name="sub", .inouts=[reg2], .outputs=[reg1], .subx-name="29/sub<-", .rm32=outputs[0], .r32=inouts[0]}
var/reg <- sub var2 {.name="sub", .inouts=[var2], .outputs=[reg], .subx-name="2b/sub->", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=outputs[0]}
sub-from var1, var2/reg {.name="sub-from", .inouts=[var1, var2], .subx-name="29/sub<-", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=inouts[1]}
var/eax <- sub n {.name="sub", .inouts=[n], .outputs=[eax], .subx-name="2d/sub-from-eax", .imm32=inouts[0]}
var/reg <- sub n {.name="sub", .inouts=[n], .outputs=[reg], .subx-name="81 5/subop/subtract", .rm32=outputs[0], .imm32=inouts[0]}
sub-from var, n {.name="sub-from", .inouts=[var, n], .subx-name="81 5/subop/subtract", .rm32="*(ebp+" inouts[0].stack-offset ")", .imm32=inouts[1]}
var1/reg1 <- and var2/reg2 {.name="and", .inouts=[reg2], .outputs=[reg1], .subx-name="21/and<-", .rm32=outputs[0], .r32=inouts[0]}
var/reg <- and var2 {.name="and", .inouts=[var2], .outputs=[reg], .subx-name="23/and->", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=outputs[0]}
and-with var1, var2/reg {.name="and-with", .inouts=[var1, reg], .subx-name="21/and<-", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=inouts[1]}
var/eax <- and n {.name="and", .inouts=[n], .outputs=[eax], .subx-name="25/and-with-eax", .imm32=inouts[0]}
var/reg <- and n {.name="and", .inouts=[n], .outputs=[reg], .subx-name="81 4/subop/and", .rm32=outputs[0], .imm32=inouts[0]}
and-with var, n {.name="and-with", .inouts=[var, n], .subx-name="81 4/subop/and", .rm32="*(ebp+" inouts[0].stack-offset ")", .imm32=inouts[1]}
var1/reg1 <- or var2/reg2 {.name="or", .inouts=[reg2], .outputs=[reg1], .subx-name="09/or<-", .rm32=outputs[0], .r32=inouts[0]}
var/reg <- or var2 {.name="or", .inouts=[var2], .outputs=[reg], .subx-name="0b/or->", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=outputs[0]}
or-with var1, var2/reg {.name="or-with", .inouts=[var1, reg], .subx-name="09/or<-", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=inouts[1]}
var/eax <- or n {.name="or", .inouts=[n], .outputs=[eax], .subx-name="0d/or-with-eax", .imm32=inouts[0]}
var/reg <- or n {.name="or", .inouts=[n], .outputs=[reg], .subx-name="81 1/subop/or", .rm32=outputs[0], .imm32=inouts[0]}
or-with var, n {.name="or-with", .inouts=[var, n], .subx-name="81 1/subop/or", .rm32="*(ebp+" inouts[0].stack-offset ")", .imm32=inouts[1]}
var1/reg1 <- xor var2/reg2 {.name="xor", .inouts=[reg2], .outputs=[reg1], .subx-name="31/xor<-", .rm32=outputs[0], .r32=inouts[0]}
var/reg <- xor var2 {.name="xor", .inouts=[var2], .outputs=[reg], .subx-name="33/xor->", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=outputs[0]}
xor-with var1, var2/reg {.name="xor-with", .inouts=[var1, reg], .subx-name="31/xor<-", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=inouts[1]}
var/eax <- xor n {.name="xor", .inouts=[n], .outputs=[eax], .subx-name="35/xor-with-eax", .imm32=inouts[0]}
var/reg <- xor n {.name="xor", .inouts=[n], .outputs=[reg], .subx-name="81 6/subop/xor", .rm32=outputs[0], .imm32=inouts[0]}
xor-with var, n {.name="xor-with", .inouts=[var, n], .subx-name="81 6/subop/xor", .rm32="*(ebp+" inouts[0].stack-offset ")", .imm32=inouts[1]}
var/eax <- copy n {.name="copy", .inouts=[n], .outputs=[eax], .subx-name="b8/copy-to-eax", .imm32=inouts[0]}
var/ecx <- copy n {.name="copy", .inouts=[n], .outputs=[ecx], .subx-name="b9/copy-to-ecx", .imm32=inouts[0]}
var/edx <- copy n {.name="copy", .inouts=[n], .outputs=[edx], .subx-name="ba/copy-to-edx", .imm32=inouts[0]}
var/ebx <- copy n {.name="copy", .inouts=[n], .outputs=[ebx], .subx-name="bb/copy-to-ebx", .imm32=inouts[0]}
var/esi <- copy n {.name="copy", .inouts=[n], .outputs=[esi], .subx-name="be/copy-to-esi", .imm32=inouts[0]}
var/edi <- copy n {.name="copy", .inouts=[n], .outputs=[edi], .subx-name="bf/copy-to-edi", .imm32=inouts[0]}
var1/reg1 <- copy var2/reg2 {.name="copy", .inouts=[reg2], .outputs=[reg1], .subx-name="89/copy-to", .rm32=outputs[0], .r32=inouts[0]}
copy-to var1, var2/reg {.name="copy-to", .inouts=[var1, var2], .subx-name="01/add<-", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=inouts[1]}
var/reg <- copy var2 {.name="copy", .inouts=[var2], .outputs=[reg], .subx-name="8b/copy-from", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=outputs[0]}
var/reg <- copy n {.name="copy", .inouts=[n], .outputs=[reg], .subx-name="c7 0/subop/copy", .rm32=outputs[0], .imm32=inouts[0]}
copy-to var, n {.name="copy-to", .inouts=[var, n], .subx-name="c7 0/subop/copy", .rm32="*(ebp+" inouts[0].stack-offset ")", .imm32=inouts[1]}
compare var1, var2/reg {.name="compare", .inouts=[var1, reg], .subx-name="39/compare->", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=inouts[1]}
compare var1/reg, var2 {.name="compare", .inouts=[reg, var2], .subx-name="3b/compare<-", .rm32="*(ebp+" inouts[1].stack-offset ")", .r32=inouts[0]}
compare var/eax, n {.name="compare", .inouts=[eax, n], .subx-name="3d/compare-eax-with", .imm32=inouts[1]}
compare var, n {.name="compare", .inouts=[var, n], .subx-name="81 7/subop/compare", .rm32="*(ebp+" inouts[0].stack-offset ")", .imm32=inouts[1]}
var/reg <- multiply var2 {.name="multiply", .inouts=[var2], .outputs=[reg], .subx-name="0f af/multiply", .rm32="*(ebp+" inouts[0].stack-offset ")", .r32=outputs[0]}
Jumps have a slightly simpler format. Most of the time they take no inouts or
outputs. Occasionally you give them a label for a block to jump to the start
or end of.
break-if-= {.name="break-if-=", .subx-name="0f 84/jump-if-= break/disp32"}
break-if-= label {.name="break-if-=", .inouts=[label], .subx-name="0f 84/jump-if-=", .disp32=inouts[0] ":break"}
break-if-!= {.name="break-if-!=", .subx-name="0f 85/jump-if-!= break/disp32"}
break-if-!= label {.name="break-if-!=", .inouts=[label], .subx-name="0f 85/jump-if-!=", .disp32=inouts[0] ":break"}
Inequalities are similar, but have unsigned and signed variants. We assume
unsigned variants are only ever used to compare addresses.
break-if-addr< {.name="break-if-addr<", .subx-name="0f 82/jump-if-addr< break/disp32"}
break-if-addr< label {.name="break-if-addr<", .inouts=[label], .subx-name="0f 82/jump-if-addr<", .disp32=inouts[0] ":break"}
break-if-addr> {.name="break-if-addr>", .subx-name="0f 87/jump-if-addr> break/disp32"}
break-if-addr> label {.name="break-if-addr>", .inouts=[label], .subx-name="0f 87/jump-if-addr>", .disp32=inouts[0] ":break"}
break-if-addr<= {.name="break-if-addr<=", .subx-name="0f 86/jump-if-addr<= break/disp32"}
break-if-addr<= label {.name="break-if-addr<=", .inouts=[label], .subx-name="0f 86/jump-if-addr<=", .disp32=inouts[0] ":break"}
break-if-addr>= {.name="break-if-addr>=", .subx-name="0f 83/jump-if-addr>= break/disp32"}
break-if-addr>= label {.name="break-if-addr>=", .inouts=[label], .subx-name="0f 83/jump-if-addr>=", .disp32=inouts[0] ":break"}
break-if-< {.name="break-if-<", .subx-name="0f 8c/jump-if-< break/disp32"}
break-if-< label {.name="break-if-<", .inouts=[label], .subx-name="0f 8c/jump-if-<", .disp32=inouts[0] ":break"}
break-if-> {.name="break-if->", .subx-name="0f 8f/jump-if-> break/disp32"}
break-if-> label {.name="break-if->", .inouts=[label], .subx-name="0f 8f/jump-if->", .disp32=inouts[0] ":break"}
break-if-<= {.name="break-if-<=", .subx-name="0f 8e/jump-if-<= break/disp32"}
break-if-<= label {.name="break-if-<=", .inouts=[label], .subx-name="0f 8e/jump-if-<=", .disp32=inouts[0] ":break"}
break-if->= {.name="break-if->=", .subx-name="0f 8d/jump-if->= break/disp32"}
break-if->= label {.name="break-if->=", .inouts=[label], .subx-name="0f 8d/jump-if->=", .disp32=inouts[0] ":break"}
Finally, we repeat all the 'break' variants almost identically for 'loop'
instructions. This works because the compiler inserts ':loop' labels at the
start of such named blocks, and ':break' labels at the end.
loop-if-= {.name="loop-if-=", .subx-name="0f 84/jump-if-= loop/disp32"}
loop-if-= label {.name="loop-if-=", .inouts=[label], .subx-name="0f 84/jump-if-=", .disp32=inouts[0] ":loop"}
loop-if-!= {.name="loop-if-!=", .subx-name="0f 85/jump-if-!= loop/disp32"}
loop-if-!= label {.name="loop-if-!=", .inouts=[label], .subx-name="0f 85/jump-if-!=", .disp32=inouts[0] ":loop"}
loop-if-addr< {.name="loop-if-addr<", .subx-name="0f 82/jump-if-addr< loop/disp32"}
loop-if-addr< label {.name="loop-if-addr<", .inouts=[label], .subx-name="0f 82/jump-if-addr<", .disp32=inouts[0] ":loop"}
loop-if-addr> {.name="loop-if-addr>", .subx-name="0f 87/jump-if-addr> loop/disp32"}
loop-if-addr> label {.name="loop-if-addr>", .inouts=[label], .subx-name="0f 87/jump-if-addr>", .disp32=inouts[0] ":loop"}
loop-if-addr<= {.name="loop-if-addr<=", .subx-name="0f 86/jump-if-addr<= loop/disp32"}
loop-if-addr<= label {.name="loop-if-addr<=", .inouts=[label], .subx-name="0f 86/jump-if-addr<=", .disp32=inouts[0] ":loop"}
loop-if-addr>= {.name="loop-if-addr>=", .subx-name="0f 83/jump-if-addr>= loop/disp32"}
loop-if-addr>= label {.name="loop-if-addr>=", .inouts=[label], .subx-name="0f 83/jump-if-addr>=", .disp32=inouts[0] ":loop"}
loop-if-< {.name="loop-if-<", .subx-name="0f 8c/jump-if-< loop/disp32"}
loop-if-< label {.name="loop-if-<", .inouts=[label], .subx-name="0f 8c/jump-if-<", .disp32=inouts[0] ":loop"}
loop-if-> {.name="loop-if->", .subx-name="0f 8f/jump-if-> loop/disp32"}
loop-if-> label {.name="loop-if->", .inouts=[label], .subx-name="0f 8f/jump-if->", .disp32=inouts[0] ":loop"}
loop-if-<= {.name="loop-if-<=", .subx-name="0f 8e/jump-if-<= loop/disp32"}
loop-if-<= label {.name="loop-if-<=", .inouts=[label], .subx-name="0f 8e/jump-if-<=", .disp32=inouts[0] ":loop"}
loop-if->= {.name="loop-if->=", .subx-name="0f 8d/jump-if->= loop/disp32"}
loop-if->= label {.name="loop-if->=", .inouts=[label], .subx-name="0f 8d/jump-if->=", .disp32=inouts[0] ":loop"}
There are also unconditional loop instructions. So far it doesn't seem like
unconditional breaks have much use.
loop {.name="loop", .subx-name="e9/jump loop/disp32"}
loop label {.name="loop", .inouts=[label], .subx-name="e9/jump", .disp32=inouts[0] ":loop"}
vim:ft=c:nowrap