wbrown’s gists

wbrown / function-from-heap.ll

Last active December 28, 2015 00:59

This LLVM IR shows the logic that is used to store function pointers in a global heap, which is then retrieved and cast as a function to be executed. It crashes right when it tries to execute the pointer.

	; constants to help with multiplatform stuff
	%pntr = type i64*
	%cell = type i64

	; for ease of debugging, allows us to print a value to stdout
	@valueString = internal constant [7 x i8] c"%llu\0D\0A\00"

	declare i32 @printf(i8*, ... )

	define void @printValue32(i32 %value) {

wbrown / forth-opt.ll

Created November 11, 2013 20:29

Output of: `clouddrift:experiments wbrown$ opt-3.3 -std-link-opts -S` on https://github.com/ephsec/svforth/blob/master/experiments/forth.ll

	; ModuleID = 'forth.ll'

	@stackString = internal constant [13 x i8] c"%llu: %llu\0D\0A\00"
	@heapPtr = internal unnamed_addr global i64* null
	@heapSize = internal unnamed_addr global i1 false
	@execIdx = internal unnamed_addr global i64 0
	@stackIdx = internal unnamed_addr global i64 0

	; Function Attrs: nounwind
	declare i32 @printf(i8* nocapture, ...) #0

wbrown / bugpoint-reduced-simplified.ll

Created November 11, 2013 22:42

With noreturn added into the calls.

	; ModuleID = 'bugpoint-reduced-simplified.bc'
	target triple = "x86_64-apple-darwin13.0.0"

	@valueString = internal constant [7 x i8] c"%llu\0D\0A\00"
	@stackString = internal constant [13 x i8] c"%llu: %llu\0D\0A\00"
	@heapPtr = weak global i64* null
	@heapSize = weak global i64 0
	@execIdx = weak global i64 0
	@stackIdx = weak global i64 0
	@currIns = weak global i64 0

wbrown / forth.ll

Created November 11, 2013 23:12

noreturn optimization issues

	%pntr = type i64*
	%int = type i64
	%cell = type i64
	%WORD = type void ()*

	; *****************************************************************************
	; stdlib functions
	; *****************************************************************************

	declare i32 @puts(i8*)

wbrown / stack-cc10.ll

Last active December 28, 2015 08:19

I am not sure why, but values that I push onto the stack are disappearing past the last value I pushed. Output:

	; clouddrift:experiments wbrown$ lli-3.3 test.ll
	; 10 --> @140734656409551
	; 11 --> @140734656409550
	; 12 --> @140734656409549
	; @140734656409549 --> 12
	; @140734656409550 --> 0
	; @140734656409551 --> 0


	%cell = type i64

wbrown / gist:7534739

Last active December 28, 2015 17:19

LLVM's x86 code generation from the IR is very impressive in that it recognizes sub-blocks in common and does jumps to them.

Below is the handwritten LLVM IR for SP_2SWAP and SP_ROT

SP_2SWAP:

kernel.SP_2SWAP:
    ; swap top two pairs of elements on the stack
    ;   pop %eax
    ;   pop %ebx
    ;   pop %ecx
    ;   pop %edx

wbrown / cpu-comparison.md

Last active December 19, 2020 00:19

Comparison of Forth VM performance across CPUs

CPU	ops/µs	TDP (w)	Core	TDP/Core	ghz	hz/op	op/µs/TDPc	op/µs*core
Apple M1	1,241	20	4	5	2.8	2.25	310.25	4,964
Apple A12z	895	16	4	4	2.6	2.90	223.75	3,580
Ryzen 3950x	1,094	105	16	6.5	4.0	3.65	168.30	17,504
Intel i7-10700k	1,251	125	8	15.625	5.0	3.99	80.06	10,008

Wes Brown wbrown