From 0102aa377a39f9d5e53b7c95571058cac7c7f7ad Mon Sep 17 00:00:00 2001
From: Kartik Agaram <vc@akkartik.com>
Date: Wed, 4 Nov 2020 17:46:07 -0800
Subject: 7176 - type checks for 'copy' instruction

---
 apps/factorial.mu |   2 +-
 apps/mu           | Bin 493268 -> 497992 bytes
 apps/mu.subx      | 575 ++++++++++++++++++++++++++++++++++++++++++++----------
 3 files changed, 473 insertions(+), 104 deletions(-)

diff --git a/apps/factorial.mu b/apps/factorial.mu
index bb335b0a..15ac8cf4 100644
--- a/apps/factorial.mu
+++ b/apps/factorial.mu
@@ -36,7 +36,7 @@ fn test-factorial {
   check-ints-equal result, 0x78, "F - test-factorial"
 }
 
-fn main args-on-stack: (addr array (addr array byte)) -> _/ebx: int {
+fn main args-on-stack: (addr array addr array byte) -> _/ebx: int {
   var args/eax: (addr array addr array byte) <- copy args-on-stack
   # len = length(args)
   var len/ecx: int <- length args
diff --git a/apps/mu b/apps/mu
index 1800d2cc..6ff5b313 100755
Binary files a/apps/mu and b/apps/mu differ
diff --git a/apps/mu.subx b/apps/mu.subx
index 1816220f..26985875 100644
--- a/apps/mu.subx
+++ b/apps/mu.subx
@@ -6106,8 +6106,7 @@ test-convert-function-call-with-arg-of-user-defined-type-by-reference:
     (write _test-input-stream "  foo b\n")
     (write _test-input-stream "}\n")
     (write _test-input-stream "fn foo x: (addr t) {\n")
-    (write _test-input-stream "  var x/ecx: (addr int) <- copy x\n")
-    (write _test-input-stream "  increment *x\n")
+    (write _test-input-stream "  var x/ecx: (addr t) <- copy x\n")
     (write _test-input-stream "}\n")
     (write _test-input-stream "type t {\n")
     (write _test-input-stream "  x: int\n")
@@ -6154,14 +6153,13 @@ test-convert-function-call-with-arg-of-user-defined-type-by-reference:
     (check-next-stream-line-equal _test-output-stream "$foo:0x00000002:loop:"   "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/24")
     (check-next-stream-line-equal _test-output-stream "    ff 6/subop/push %ecx"  "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/25")
     (check-next-stream-line-equal _test-output-stream "    8b/-> *(ebp+0x00000008) 0x00000001/r32"  "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/26")
-    (check-next-stream-line-equal _test-output-stream "    ff 0/subop/increment *ecx"  "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/27")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx" "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/28")
-    (check-next-stream-line-equal _test-output-stream "  }"                     "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/29")
-    (check-next-stream-line-equal _test-output-stream "$foo:0x00000002:break:"  "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/30")
-    (check-next-stream-line-equal _test-output-stream "  # . epilogue"          "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/31")
-    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"  "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/32")
-    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"         "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/33")
-    (check-next-stream-line-equal _test-output-stream "  c3/return"             "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/34")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx" "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/27")
+    (check-next-stream-line-equal _test-output-stream "  }"                     "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/28")
+    (check-next-stream-line-equal _test-output-stream "$foo:0x00000002:break:"  "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/29")
+    (check-next-stream-line-equal _test-output-stream "  # . epilogue"          "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/30")
+    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"  "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/31")
+    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"         "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/32")
+    (check-next-stream-line-equal _test-output-stream "  c3/return"             "F - test-convert-function-call-with-arg-of-user-defined-type-by-reference/33")
     # . epilogue
     89/<- %esp 5/r32/ebp
     5d/pop-to-ebp
@@ -6496,7 +6494,7 @@ test-add-with-non-number:
 #?     # }}}
     # check output
     (check-stream-equal _test-output-stream  ""  "F - test-add-with-non-number: output should be empty")
-    (check-next-stream-line-equal _test-error-stream  "fn foo: stmt add: only non-addr scalar args permitted"  "F - test-add-with-non-number: error message")
+    (check-next-stream-line-equal _test-error-stream  "fn foo: stmt add: output must be a non-addr scalar"  "F - test-add-with-non-number: error message")
     # check that stop(1) was called
     (check-ints-equal *(edx+4) 2 "F - test-add-with-non-number: exit status")
     # don't restore from ebp
@@ -6528,6 +6526,321 @@ test-add-with-addr-dereferenced:
     5d/pop-to-ebp
     c3/return
 
+test-copy-with-no-inout:
+    # . prologue
+    55/push-ebp
+    89/<- %ebp 4/r32/esp
+    # setup
+    (clear-stream _test-input-stream)
+    (clear-stream $_test-input-buffered-file->buffer)
+    (clear-stream _test-output-stream)
+    (clear-stream $_test-output-buffered-file->buffer)
+    (clear-stream _test-error-stream)
+    (clear-stream $_test-error-buffered-file->buffer)
+    # var ed/edx: exit-descriptor = tailor-exit-descriptor(16)
+    68/push 0/imm32
+    68/push 0/imm32
+    89/<- %edx 4/r32/esp
+    (tailor-exit-descriptor %edx 0x10)
+    #
+    (write _test-input-stream "fn foo {\n")
+    (write _test-input-stream "  var x/eax: boolean <- copy\n")
+    (write _test-input-stream "}\n")
+    # convert
+    (convert-mu _test-input-buffered-file _test-output-buffered-file _test-error-buffered-file %edx)
+    # registers except esp clobbered at this point
+    # restore ed
+    89/<- %edx 4/r32/esp
+    (flush _test-output-buffered-file)
+    (flush _test-error-buffered-file)
+#?     # dump _test-error-stream {{{
+#?     (write 2 "^")
+#?     (write-stream 2 _test-error-stream)
+#?     (write 2 "$\n")
+#?     (rewind-stream _test-error-stream)
+#?     # }}}
+    # check output
+    (check-stream-equal _test-output-stream  ""  "F - test-copy-with-no-inout: output should be empty")
+    (check-next-stream-line-equal _test-error-stream  "fn foo: stmt 'copy' expects an inout"  "F - test-copy-with-no-inout: error message")
+    # check that stop(1) was called
+    (check-ints-equal *(edx+4) 2 "F - test-copy-with-no-inout: exit status")
+    # don't restore from ebp
+    81 0/subop/add %esp 8/imm32
+    # . epilogue
+    5d/pop-to-ebp
+    c3/return
+
+test-copy-with-multiple-inouts:
+    # . prologue
+    55/push-ebp
+    89/<- %ebp 4/r32/esp
+    # setup
+    (clear-stream _test-input-stream)
+    (clear-stream $_test-input-buffered-file->buffer)
+    (clear-stream _test-output-stream)
+    (clear-stream $_test-output-buffered-file->buffer)
+    (clear-stream _test-error-stream)
+    (clear-stream $_test-error-buffered-file->buffer)
+    # var ed/edx: exit-descriptor = tailor-exit-descriptor(16)
+    68/push 0/imm32
+    68/push 0/imm32
+    89/<- %edx 4/r32/esp
+    (tailor-exit-descriptor %edx 0x10)
+    #
+    (write _test-input-stream "fn foo {\n")
+    (write _test-input-stream "  var x/eax: boolean <- copy 0, 0\n")
+    (write _test-input-stream "}\n")
+    # convert
+    (convert-mu _test-input-buffered-file _test-output-buffered-file _test-error-buffered-file %edx)
+    # registers except esp clobbered at this point
+    # restore ed
+    89/<- %edx 4/r32/esp
+    (flush _test-output-buffered-file)
+    (flush _test-error-buffered-file)
+#?     # dump _test-error-stream {{{
+#?     (write 2 "^")
+#?     (write-stream 2 _test-error-stream)
+#?     (write 2 "$\n")
+#?     (rewind-stream _test-error-stream)
+#?     # }}}
+    # check output
+    (check-stream-equal _test-output-stream  ""  "F - test-copy-with-no-inout: output should be empty")
+    (check-next-stream-line-equal _test-error-stream  "fn foo: stmt 'copy' must have just one inout"  "F - test-copy-with-no-inout: error message")
+    # check that stop(1) was called
+    (check-ints-equal *(edx+4) 2 "F - test-copy-with-no-inout: exit status")
+    # don't restore from ebp
+    81 0/subop/add %esp 8/imm32
+    # . epilogue
+    5d/pop-to-ebp
+    c3/return
+
+test-copy-with-no-output:
+    # . prologue
+    55/push-ebp
+    89/<- %ebp 4/r32/esp
+    # setup
+    (clear-stream _test-input-stream)
+    (clear-stream $_test-input-buffered-file->buffer)
+    (clear-stream _test-output-stream)
+    (clear-stream $_test-output-buffered-file->buffer)
+    (clear-stream _test-error-stream)
+    (clear-stream $_test-error-buffered-file->buffer)
+    # var ed/edx: exit-descriptor = tailor-exit-descriptor(16)
+    68/push 0/imm32
+    68/push 0/imm32
+    89/<- %edx 4/r32/esp
+    (tailor-exit-descriptor %edx 0x10)
+    #
+    (write _test-input-stream "fn foo {\n")
+    (write _test-input-stream "  copy 0\n")
+    (write _test-input-stream "}\n")
+    # convert
+    (convert-mu _test-input-buffered-file _test-output-buffered-file _test-error-buffered-file %edx)
+    # registers except esp clobbered at this point
+    # restore ed
+    89/<- %edx 4/r32/esp
+    (flush _test-output-buffered-file)
+    (flush _test-error-buffered-file)
+#?     # dump _test-error-stream {{{
+#?     (write 2 "^")
+#?     (write-stream 2 _test-error-stream)
+#?     (write 2 "$\n")
+#?     (rewind-stream _test-error-stream)
+#?     # }}}
+    # check output
+    (check-stream-equal _test-output-stream  ""  "F - test-copy-with-no-output: output should be empty")
+    (check-next-stream-line-equal _test-error-stream  "fn foo: stmt 'copy' expects an output"  "F - test-copy-with-no-output: error message")
+    # check that stop(1) was called
+    (check-ints-equal *(edx+4) 2 "F - test-copy-with-no-output: exit status")
+    # don't restore from ebp
+    81 0/subop/add %esp 8/imm32
+    # . epilogue
+    5d/pop-to-ebp
+    c3/return
+
+test-copy-with-multiple-outputs:
+    # . prologue
+    55/push-ebp
+    89/<- %ebp 4/r32/esp
+    # setup
+    (clear-stream _test-input-stream)
+    (clear-stream $_test-input-buffered-file->buffer)
+    (clear-stream _test-output-stream)
+    (clear-stream $_test-output-buffered-file->buffer)
+    (clear-stream _test-error-stream)
+    (clear-stream $_test-error-buffered-file->buffer)
+    # var ed/edx: exit-descriptor = tailor-exit-descriptor(16)
+    68/push 0/imm32
+    68/push 0/imm32
+    89/<- %edx 4/r32/esp
+    (tailor-exit-descriptor %edx 0x10)
+    #
+    (write _test-input-stream "fn foo -> _/eax: int {\n")
+    (write _test-input-stream "  var x/eax: boolean <- copy 0\n")
+    (write _test-input-stream "  var y/ecx: boolean <- copy 0\n")
+    (write _test-input-stream "  x, y <- copy 0\n")
+    (write _test-input-stream "  return x\n")
+    (write _test-input-stream "}\n")
+    # convert
+    (convert-mu _test-input-buffered-file _test-output-buffered-file _test-error-buffered-file %edx)
+    # registers except esp clobbered at this point
+    # restore ed
+    89/<- %edx 4/r32/esp
+    (flush _test-output-buffered-file)
+    (flush _test-error-buffered-file)
+#?     # dump _test-error-stream {{{
+#?     (write 2 "^")
+#?     (write-stream 2 _test-error-stream)
+#?     (write 2 "$\n")
+#?     (rewind-stream _test-error-stream)
+#?     # }}}
+    # check output
+    (check-stream-equal _test-output-stream  ""  "F - test-copy-with-multiple-outputs: output should be empty")
+    (check-next-stream-line-equal _test-error-stream  "fn foo: stmt 'copy' must have just one output"  "F - test-copy-with-multiple-outputs: error message")
+    # check that stop(1) was called
+    (check-ints-equal *(edx+4) 2 "F - test-copy-with-multiple-outputs: exit status")
+    # don't restore from ebp
+    81 0/subop/add %esp 8/imm32
+    # . epilogue
+    5d/pop-to-ebp
+    c3/return
+
+test-copy-invalid-value-to-address:
+    # . prologue
+    55/push-ebp
+    89/<- %ebp 4/r32/esp
+    # setup
+    (clear-stream _test-input-stream)
+    (clear-stream $_test-input-buffered-file->buffer)
+    (clear-stream _test-output-stream)
+    (clear-stream $_test-output-buffered-file->buffer)
+    (clear-stream _test-error-stream)
+    (clear-stream $_test-error-buffered-file->buffer)
+    # var ed/edx: exit-descriptor = tailor-exit-descriptor(16)
+    68/push 0/imm32
+    68/push 0/imm32
+    89/<- %edx 4/r32/esp
+    (tailor-exit-descriptor %edx 0x10)
+    #
+    (write _test-input-stream "fn foo -> _/eax: int {\n")
+    (write _test-input-stream "  var x/eax: int <- copy 0\n")
+    (write _test-input-stream "  var y/ecx: (addr int) <- copy x\n")
+    (write _test-input-stream "  return x\n")
+    (write _test-input-stream "}\n")
+    # convert
+    (convert-mu _test-input-buffered-file _test-output-buffered-file _test-error-buffered-file %edx)
+    # registers except esp clobbered at this point
+    # restore ed
+    89/<- %edx 4/r32/esp
+    (flush _test-output-buffered-file)
+    (flush _test-error-buffered-file)
+#?     # dump _test-error-stream {{{
+#?     (write 2 "^")
+#?     (write-stream 2 _test-error-stream)
+#?     (write 2 "$\n")
+#?     (rewind-stream _test-error-stream)
+#?     # }}}
+    # check output
+    (check-stream-equal _test-output-stream  ""  "F - test-copy-invalid-value-to-address: output should be empty")
+    (check-next-stream-line-equal _test-error-stream  "fn foo: stmt copy: output must be a non-addr scalar"  "F - test-copy-invalid-value-to-address: error message")
+    # check that stop(1) was called
+    (check-ints-equal *(edx+4) 2 "F - test-copy-invalid-value-to-address: exit status")
+    # don't restore from ebp
+    81 0/subop/add %esp 8/imm32
+    # . epilogue
+    5d/pop-to-ebp
+    c3/return
+
+test-copy-to-non-register:
+    # . prologue
+    55/push-ebp
+    89/<- %ebp 4/r32/esp
+    # setup
+    (clear-stream _test-input-stream)
+    (clear-stream $_test-input-buffered-file->buffer)
+    (clear-stream _test-output-stream)
+    (clear-stream $_test-output-buffered-file->buffer)
+    (clear-stream _test-error-stream)
+    (clear-stream $_test-error-buffered-file->buffer)
+    # var ed/edx: exit-descriptor = tailor-exit-descriptor(16)
+    68/push 0/imm32
+    68/push 0/imm32
+    89/<- %edx 4/r32/esp
+    (tailor-exit-descriptor %edx 0x10)
+    #
+    (write _test-input-stream "fn foo {\n")
+    (write _test-input-stream "  var x: int\n")
+    (write _test-input-stream "  x <- copy 0\n")
+    (write _test-input-stream "}\n")
+    # convert
+    (convert-mu _test-input-buffered-file _test-output-buffered-file _test-error-buffered-file %edx)
+    # registers except esp clobbered at this point
+    # restore ed
+    89/<- %edx 4/r32/esp
+    (flush _test-output-buffered-file)
+    (flush _test-error-buffered-file)
+#?     # dump _test-error-stream {{{
+#?     (write 2 "^")
+#?     (write-stream 2 _test-error-stream)
+#?     (write 2 "$\n")
+#?     (rewind-stream _test-error-stream)
+#?     # }}}
+    # check output
+    (check-stream-equal _test-output-stream  ""  "F - test-copy-to-non-register: output should be empty")
+    (check-next-stream-line-equal _test-error-stream  "fn foo: stmt copy: output 'x' not in a register"  "F - test-copy-to-non-register: error message")
+    # check that stop(1) was called
+    (check-ints-equal *(edx+4) 2 "F - test-copy-to-non-register: exit status")
+    # don't restore from ebp
+    81 0/subop/add %esp 8/imm32
+    # . epilogue
+    5d/pop-to-ebp
+    c3/return
+
+test-copy-non-scalar:
+    # . prologue
+    55/push-ebp
+    89/<- %ebp 4/r32/esp
+    # setup
+    (clear-stream _test-input-stream)
+    (clear-stream $_test-input-buffered-file->buffer)
+    (clear-stream _test-output-stream)
+    (clear-stream $_test-output-buffered-file->buffer)
+    (clear-stream _test-error-stream)
+    (clear-stream $_test-error-buffered-file->buffer)
+    # var ed/edx: exit-descriptor = tailor-exit-descriptor(16)
+    68/push 0/imm32
+    68/push 0/imm32
+    89/<- %edx 4/r32/esp
+    (tailor-exit-descriptor %edx 0x10)
+    #
+    (write _test-input-stream "fn foo {\n")
+    (write _test-input-stream "  var x: (handle int)\n")
+    (write _test-input-stream "  var y/eax: int <- copy x\n")
+    (write _test-input-stream "}\n")
+    # convert
+    (convert-mu _test-input-buffered-file _test-output-buffered-file _test-error-buffered-file %edx)
+    # registers except esp clobbered at this point
+    # restore ed
+    89/<- %edx 4/r32/esp
+    (flush _test-output-buffered-file)
+    (flush _test-error-buffered-file)
+#?     # dump _test-error-stream {{{
+#?     (write 2 "^")
+#?     (write-stream 2 _test-error-stream)
+#?     (write 2 "$\n")
+#?     (rewind-stream _test-error-stream)
+#?     # }}}
+    # check output
+    (check-stream-equal _test-output-stream  ""  "F - test-copy-non-scalar: output should be empty")
+    (check-next-stream-line-equal _test-error-stream  "fn foo: stmt copy: 'y' is too large to fit in a register"  "F - test-copy-non-scalar: error message")
+    # check that stop(1) was called
+    (check-ints-equal *(edx+4) 2 "F - test-copy-non-scalar: exit status")
+    # don't restore from ebp
+    81 0/subop/add %esp 8/imm32
+    # . epilogue
+    5d/pop-to-ebp
+    c3/return
+
 test-get-with-wrong-field:
     # . prologue
     55/push-ebp
@@ -7664,51 +7977,6 @@ test-index-with-addr-base-on-stack:
     5d/pop-to-ebp
     c3/return
 
-test-index-with-array-base-in-register:
-    # . prologue
-    55/push-ebp
-    89/<- %ebp 4/r32/esp
-    # setup
-    (clear-stream _test-input-stream)
-    (clear-stream $_test-input-buffered-file->buffer)
-    (clear-stream _test-output-stream)
-    (clear-stream $_test-output-buffered-file->buffer)
-    (clear-stream _test-error-stream)
-    (clear-stream $_test-error-buffered-file->buffer)
-    # var ed/edx: exit-descriptor = tailor-exit-descriptor(16)
-    68/push 0/imm32
-    68/push 0/imm32
-    89/<- %edx 4/r32/esp
-    (tailor-exit-descriptor %edx 0x10)
-    #
-    (write _test-input-stream "fn foo {\n")
-    (write _test-input-stream "  var a/eax: (array int 3) <- copy 0\n")
-    (write _test-input-stream "  var c/ecx: (addr int) <- index a, 0\n")
-    (write _test-input-stream "}\n")
-    # convert
-    (convert-mu _test-input-buffered-file _test-output-buffered-file _test-error-buffered-file %edx)
-    # registers except esp clobbered at this point
-    # restore ed
-    89/<- %edx 4/r32/esp
-    (flush _test-output-buffered-file)
-    (flush _test-error-buffered-file)
-#?     # dump _test-error-stream {{{
-#?     (write 2 "^")
-#?     (write-stream 2 _test-error-stream)
-#?     (write 2 "$\n")
-#?     (rewind-stream _test-error-stream)
-#?     # }}}
-    # check output
-    (check-stream-equal _test-output-stream  ""  "F - test-index-with-array-base-in-register: output should be empty")
-    (check-next-stream-line-equal _test-error-stream  "fn foo: stmt index: var 'a' is an array, and so must live on the stack"  "F - test-index-with-array-base-in-register: error message")
-    # check that stop(1) was called
-    (check-ints-equal *(edx+4) 2 "F - test-index-with-array-base-in-register: exit status")
-    # don't restore from ebp
-    81 0/subop/add %esp 8/imm32
-    # . epilogue
-    5d/pop-to-ebp
-    c3/return
-
 test-index-with-wrong-index-type:
     # . prologue
     55/push-ebp
@@ -8908,7 +9176,7 @@ test-compute-offset-with-too-many-outputs:
     #
     (write _test-input-stream "fn foo {\n")
     (write _test-input-stream "  var a: (array int 3)\n")
-    (write _test-input-stream "  var b/eax: (offset int) <- copy 0\n")
+    (write _test-input-stream "  var b/eax: (offset int) <- compute-offset a, 0\n")
     (write _test-input-stream "  var c/ecx: (addr int) <- copy 0\n")
     (write _test-input-stream "  b, c <- compute-offset a, 0\n")
     (write _test-input-stream "}\n")
@@ -10187,51 +10455,6 @@ test-length-with-addr-base-on-stack:
     5d/pop-to-ebp
     c3/return
 
-test-length-with-array-base-in-register:
-    # . prologue
-    55/push-ebp
-    89/<- %ebp 4/r32/esp
-    # setup
-    (clear-stream _test-input-stream)
-    (clear-stream $_test-input-buffered-file->buffer)
-    (clear-stream _test-output-stream)
-    (clear-stream $_test-output-buffered-file->buffer)
-    (clear-stream _test-error-stream)
-    (clear-stream $_test-error-buffered-file->buffer)
-    # var ed/edx: exit-descriptor = tailor-exit-descriptor(16)
-    68/push 0/imm32
-    68/push 0/imm32
-    89/<- %edx 4/r32/esp
-    (tailor-exit-descriptor %edx 0x10)
-    #
-    (write _test-input-stream "fn foo {\n")
-    (write _test-input-stream "  var a/eax: (array int 3) <- copy 0\n")
-    (write _test-input-stream "  var c/ecx: (addr int) <- length a\n")
-    (write _test-input-stream "}\n")
-    # convert
-    (convert-mu _test-input-buffered-file _test-output-buffered-file _test-error-buffered-file %edx)
-    # registers except esp clobbered at this point
-    # restore ed
-    89/<- %edx 4/r32/esp
-    (flush _test-output-buffered-file)
-    (flush _test-error-buffered-file)
-#?     # dump _test-error-stream {{{
-#?     (write 2 "^")
-#?     (write-stream 2 _test-error-stream)
-#?     (write 2 "$\n")
-#?     (rewind-stream _test-error-stream)
-#?     # }}}
-    # check output
-    (check-stream-equal _test-output-stream  ""  "F - test-length-with-array-base-in-register: output should be empty")
-    (check-next-stream-line-equal _test-error-stream  "fn foo: stmt length: var 'a' is an array, and so must live on the stack"  "F - test-length-with-array-base-in-register: error message")
-    # check that stop(1) was called
-    (check-ints-equal *(edx+4) 2 "F - test-length-with-array-base-in-register: exit status")
-    # don't restore from ebp
-    81 0/subop/add %esp 8/imm32
-    # . epilogue
-    5d/pop-to-ebp
-    c3/return
-
 test-length-with-wrong-output-type:
     # . prologue
     55/push-ebp
@@ -16395,7 +16618,7 @@ $check-mu-numberlike-output:fail:
     8b/-> *(ebp+0xc) 0/r32/eax
     (lookup *(eax+4) *(eax+8))  # Stmt1-operation Stmt1-operation => eax
     (write-buffered *(ebp+0x14) %eax)
-    (write-buffered *(ebp+0x14) ": only non-addr scalar args permitted\n")
+    (write-buffered *(ebp+0x14) ": output must be a non-addr scalar\n")
     (flush *(ebp+0x14))
     (stop *(ebp+0x18) 1)
     # never gets here
@@ -16405,13 +16628,159 @@ check-mu-copy-stmt:  # stmt: (addr stmt), fn: (addr function), err: (addr buffer
     55/push-ebp
     89/<- %ebp 4/r32/esp
     # . save registers
+    50/push-eax
+    51/push-ecx
+    52/push-edx
+    56/push-esi
+    # var type-parameters/edx: (addr table (handle array byte) (addr type-tree) 8)
+    81 5/subop/subtract %esp 0x60/imm32
+    68/push 0x60/imm32/size
+    68/push 0/imm32/read
+    68/push 0/imm32/write
+    89/<- %edx 4/r32/esp
+$check-mu-copy-stmt:get-output:
+    # esi = stmt
+    8b/-> *(ebp+8) 6/r32/esi
+    # var output/edi: (addr stmt-var) = stmt->outputs
+    (lookup *(esi+0x14) *(esi+0x18))  # Stmt1-outputs Stmt1-outputs => eax
+    89/<- %edi 0/r32/eax
+    # zero outputs
+    3d/compare-eax-and 0/imm32
+    0f 84/jump-if-= $check-mu-copy-stmt:error-no-output/disp32
+    # > 1 output
+    (lookup *(edi+8) *(edi+0xc))  # Stmt-var-next Stmt-var-next => eax
+    3d/compare-eax-and 0/imm32
+    0f 85/jump-if-!= $check-mu-copy-stmt:error-too-many-outputs/disp32
+$check-mu-copy-stmt:get-inout:
+    # var inout/esi: (addr stmt-var) = stmt->inouts
+    (lookup *(esi+0xc) *(esi+0x10))  # Stmt1-inouts Stmt1-inouts => eax
+    89/<- %esi 0/r32/eax
+    # zero inouts
+    3d/compare-eax-and 0/imm32
+    0f 84/jump-if-= $check-mu-copy-stmt:error-no-inout/disp32
+    # > 1 inout
+    (lookup *(esi+8) *(esi+0xc))  # Stmt-var-next Stmt-var-next => eax
+    3d/compare-eax-and 0/imm32
+    0f 85/jump-if-!= $check-mu-copy-stmt:error-too-many-inouts/disp32
+$check-mu-copy-stmt:types:
+    # var inout-type/ecx: (addr type-tree) = inout->value->type
+    (lookup *esi *(esi+4))  # Stmt-var-value Stmt-var-value => eax
+    (lookup *(eax+8) *(eax+0xc))  # Var-type Var-type => eax
+    89/<- %ecx 0/r32/eax
+    # if output not in register, abort
+    (lookup *edi *(edi+4))  # Stmt-var-value Stmt-var-value => eax
+    (lookup *(eax+0x18) *(eax+0x1c))  # Var-register Var-register => eax
+    3d/compare-eax-and 0/imm32
+    0f 84/jump-if-= $check-mu-copy-stmt:error-output-not-in-register/disp32
+    # if inout is not a scalar, abort
+    (lookup *esi *(esi+4))  # Stmt-var-value Stmt-var-value => eax
+    (size-of %eax)  # => eax
+    3d/compare-eax-and 4/imm32
+    0f 8f/jump-if-> $check-mu-copy-stmt:error-inout-too-large/disp32
+    # var output-type/eax: (addr type-tree) = output->value->type
+    (lookup *edi *(edi+4))  # Stmt-var-value Stmt-var-value => eax
+    (lookup *(eax+8) *(eax+0xc))  # Var-type Var-type => eax
+    # if (inout-type == output-type) return
+    (type-match? %eax %ecx %edx)  # => eax
+    3d/compare-eax-and 0/imm32
+    0f 85/jump-if-!= $check-mu-copy-stmt:end/disp32
+    # if output is an addr and inout is 0, return
+    {
+      (lookup *edi *(edi+4))  # Stmt-var-value Stmt-var-value => eax
+      (lookup *(eax+8) *(eax+0xc))  # Var-type Var-type => eax
+      (is-mu-addr-type? %eax)  # => eax
+      3d/compare-eax-and 0/imm32/false
+      74/jump-if-= break/disp8
+      (lookup *esi *(esi+4))  # Stmt-var-value Stmt-var-value => eax
+      (lookup *eax *(eax+4))  # Var-name Var-name => eax
+      (string-equal? %eax "0")  # => eax
+      3d/compare-eax-and 0/imm32/false
+      74/jump-if-= break/disp8
+      eb/jump $check-mu-copy-stmt:end/disp8
+    }
+    # if output is not number-like, abort
+    (check-mu-numberlike-output %edi *(ebp+8) *(ebp+0xc) *(ebp+0x10) *(ebp+0x14))
 $check-mu-copy-stmt:end:
+    # . reclaim locals
+    81 0/subop/add %esp 0x6c/imm32
     # . restore registers
+    5e/pop-to-esi
+    5a/pop-to-edx
+    59/pop-to-ecx
+    58/pop-to-eax
     # . epilogue
     89/<- %esp 5/r32/ebp
     5d/pop-to-ebp
     c3/return
 
+$check-mu-copy-stmt:error-no-inout:
+    (write-buffered *(ebp+0x10) "fn ")
+    8b/-> *(ebp+0xc) 0/r32/eax
+    (lookup *eax *(eax+4))  # Function-name Function-name => eax
+    (write-buffered *(ebp+0x10) %eax)
+    (write-buffered *(ebp+0x10) ": stmt 'copy' expects an inout\n")
+    (flush *(ebp+0x10))
+    (stop *(ebp+0x14) 1)
+    # never gets here
+
+$check-mu-copy-stmt:error-too-many-inouts:
+    (write-buffered *(ebp+0x10) "fn ")
+    8b/-> *(ebp+0xc) 0/r32/eax
+    (lookup *eax *(eax+4))  # Function-name Function-name => eax
+    (write-buffered *(ebp+0x10) %eax)
+    (write-buffered *(ebp+0x10) ": stmt 'copy' must have just one inout\n")
+    (flush *(ebp+0x10))
+    (stop *(ebp+0x14) 1)
+    # never gets here
+
+$check-mu-copy-stmt:error-no-output:
+    (write-buffered *(ebp+0x10) "fn ")
+    8b/-> *(ebp+0xc) 0/r32/eax
+    (lookup *eax *(eax+4))  # Function-name Function-name => eax
+    (write-buffered *(ebp+0x10) %eax)
+    (write-buffered *(ebp+0x10) ": stmt 'copy' expects an output\n")
+    (flush *(ebp+0x10))
+    (stop *(ebp+0x14) 1)
+    # never gets here
+
+$check-mu-copy-stmt:error-output-not-in-register:
+    (write-buffered *(ebp+0x10) "fn ")
+    8b/-> *(ebp+0xc) 0/r32/eax
+    (lookup *eax *(eax+4))  # Function-name Function-name => eax
+    (write-buffered *(ebp+0x10) %eax)
+    (write-buffered *(ebp+0x10) ": stmt copy: output '")
+    (lookup *edi *(edi+4))  # Stmt-var-value Stmt-var-value => eax
+    (lookup *eax *(eax+4))  # Var-name Var-name => eax
+    (write-buffered *(ebp+0x10) %eax)
+    (write-buffered *(ebp+0x10) "' not in a register\n")
+    (flush *(ebp+0x10))
+    (stop *(ebp+0x14) 1)
+    # never gets here
+
+$check-mu-copy-stmt:error-too-many-outputs:
+    (write-buffered *(ebp+0x10) "fn ")
+    8b/-> *(ebp+0xc) 0/r32/eax
+    (lookup *eax *(eax+4))  # Function-name Function-name => eax
+    (write-buffered *(ebp+0x10) %eax)
+    (write-buffered *(ebp+0x10) ": stmt 'copy' must have just one output\n")
+    (flush *(ebp+0x10))
+    (stop *(ebp+0x14) 1)
+    # never gets here
+
+$check-mu-copy-stmt:error-inout-too-large:
+    (write-buffered *(ebp+0x10) "fn ")
+    8b/-> *(ebp+0xc) 0/r32/eax
+    (lookup *eax *(eax+4))  # Function-name Function-name => eax
+    (write-buffered *(ebp+0x10) %eax)
+    (write-buffered *(ebp+0x10) ": stmt copy: '")
+    (lookup *edi *(edi+4))  # Stmt-var-value Stmt-var-value => eax
+    (lookup *eax *(eax+4))  # Var-name Var-name => eax
+    (write-buffered *(ebp+0x10) %eax)
+    (write-buffered *(ebp+0x10) "' is too large to fit in a register\n")
+    (flush *(ebp+0x10))
+    (stop *(ebp+0x14) 1)
+    # never gets here
+
 check-mu-copy-to-stmt:  # stmt: (addr stmt), fn: (addr function), err: (addr buffered-file), ed: (addr exit-descriptor)
     # . prologue
     55/push-ebp
-- 
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