[WIP] Wrc20 code golfing

eth_contracts.nim

@@ -267,9 +267,12 @@ proc getBlockTimestamp*(): int64
 proc callDataCopy*[T](res: var T, offset: int) {.inline.} =
   callDataCopy(addr res, offset.int32, sizeof(res).int32)
 
+proc callDataCopy*(T: type, offset: int): T {.inline.} =
+  callDataCopy(addr result, offset.int32, sizeof(T).int32)
+
 proc callDataCopy*[N](res: var array[N, byte], offset: int, bytes: int) {.inline.} =
   ## copy bytes from calldata, zeroing out the rest of the array
-  callDataCopy(addr res[0], offset.int32, res.len.int32)
+  callDataCopy(addr res[0], offset.int32, bytes.int32)
   zeroMem(addr res[bytes], res.len - bytes)
 
 proc getCaller*[N](res: var array[N, byte]) {.inline.} =

examples/Makefile

@@ -0,0 +1,34 @@
+L=/home/arnetheduck/src/nlvm/ext/llvm-8.0.0.src/sha/bin
+NFLAGS=--checks:off --nlvm.target=wasm32-unknown-unknown --gc:none -l:--compress-relocations -l:--no-entry -l:--allow-undefined -l:--strip-all --noMain
+B=/home/arnetheduck/src/binaryen/bin
+
+.PHONY: all
+all: wrc20.wat wrc20opt.wat wrc20opt.ll wrc20strip.wat wrc20binaryen.wat
+	ls -l
+
+wrc20opt.wasm: wrc20opt.ll
+	$(L)/llc -filetype=obj -O2 wrc20opt.ll -o wrc20opt.o
+	$(L)/wasm-ld -o wrc20opt.wasm wrc20opt.o -O2 --strip-all --no-entry --allow-undefined --export-dynamic --compress-relocations
+
+wrc20.ll: wrc20.nim
+	nlvm c $(NFLAGS) -c -d:release --opt:size wrc20
+
+wrc20.wasm: wrc20.nim
+	nlvm c $(NFLAGS) -d:release --opt:size wrc20
+
+wrc20opt.ll: wrc20.ll
+	$(L)/opt -O2 -disable-inlining wrc20.ll | $(L)/llvm-dis > wrc20opt.ll
+
+.PHONY: clean
+clean:
+	rm -f *.wasm *.ll *.wat
+
+%.wat: %.wasm
+	wasm2wat --generate-names $< > $@
+
+wrc20strip.wasm: wrc20opt.wat
+	sed -e '/__heap_base\|__data_end\|funcref/d' -e 's/env/ethereum/g' wrc20opt.wat > wrc20tmp.wat
+	wat2wasm -o wrc20strip.wasm wrc20tmp.wat
+
+wrc20binaryen.wasm: wrc20strip.wasm
+	$(B)/wasm-opt -Os -o wrc20binaryen.wasm wrc20strip.wasm

examples/wrc20.nim

@@ -6,25 +6,20 @@
 
 import ../eth_contracts
 
-proc bigEndian64*(inp: pointer): uint64 =
-  # If we turn on the llvm inliner, it will inline calls to the bswap intrinsic
-  # causing a code size explosion - looks like for the wasm target, it doesn't
-  # count expansion that's done due to the lack of a bswap instruction.
-  # As a workaround, one needs to make sure that inlining is disabled when
-  # compiling with llvm / clang!
-  # Also as a workaround, we do a special version of bigEndian64 here that
-  # avoids some random calls that are generally needed for byte alignment but
-  # can be avoided here..
-  # TODO report upstream
-  var x = cast[ptr uint64](inp)[]
-
-  x = (x and 0x00000000FFFFFFFF'u64) shl 32'u64 or (x and 0xFFFFFFFF00000000'u64) shr 32'u64
+proc bigEndian64*(x: uint64): uint64 {.noinline.} =
+  # If we use inliner or enable the bswap intrinsic, code size explodes as wasm
+  # lacks a bswap instruction
+  var x = (x and 0x00000000FFFFFFFF'u64) shl 32'u64 or (x and 0xFFFFFFFF00000000'u64) shr 32'u64
   x = (x and 0x0000FFFF0000FFFF'u64) shl 16'u64 or (x and 0xFFFF0000FFFF0000'u64) shr 16'u64
   x = (x and 0x00FF00FF00FF00FF'u64) shl 8'u64  or (x and 0xFF00FF00FF00FF00'u64) shr 8'u64
   x
 
 template bigEndian64*(v: uint64, outp: var openArray[byte]) =
-  cast[ptr uint64](addr outp[0])[] = bigEndian64(unsafeAddr v)
+  cast[ptr uint64](addr outp[0])[] = bigEndian64(v)
+
+template bigEndian64*[N: static int](v: array[N, byte]): uint64 =
+  static: assert N >= sizeof(uint64)
+  bigEndian64(cast[ptr uint64](addr v[0])[])
 
 proc do_balance() =
   if getCallDataSize() != 24:
@@ -54,20 +49,20 @@ proc do_transfer() =
   storageLoad(recipient, recipientBalance)
 
   var
-    sb = bigEndian64(addr senderBalance)
-    v = bigEndian64(addr value)
+    sb = bigEndian64(senderBalance)
+    v = bigEndian64(value)
 
   if sb < v:
     revert(nil, 0)
 
   var
-    rb = bigEndian64(addr recipientBalance)
+    rb = bigEndian64(recipientBalance)
 
   sb -= v
   rb += v # TODO there's an overflow possible here..
 
   bigEndian64(sb, senderBalance)
-  bigEndian64(sb, recipientBalance)
+  bigEndian64(rb, recipientBalance)
 
   storageStore(sender, senderBalance)
   storageStore(recipient, recipientBalance)