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fix a long-standing bug in Mu's translator 

While all test pass, this change is disquieting. When I first designed
Mu I deliberately chose to exclude literal strings from most primitive
instructions both for type-checking and to avoid silently passing
through strange constructions. Nobody really needs to add a string to a
number, and am I sure no SubX instruction will cause a memory safety
issue when passed a string literal instead of a number?

But clearly I have no tests encoding this desire. And any string literal
could be replaced by an integer literal containing the exact same value,
so what are we protecting against anyway.

Let me fix the bug for now. If I run into problems I'll come back and do
this right.
This commit is contained in:
Kartik K. Agaram 2021-08-22 22:10:02 -07:00
parent ba4a3c5be7
commit 791a71e27e
2 changed files with 47 additions and 0 deletions
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@ -7927,6 +7927,50 @@ test-copy-null-value-to-address:
5d/pop-to-ebp
c3/return
test-copy-string-literal:
# . 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 $_test-output-buffered-file->buffer)
#
(write _test-input-stream "fn foo {\n")
(write _test-input-stream " var y/ecx: (addr array byte) <- copy \"a\"\n")
(write _test-input-stream "}\n")
# convert
(convert-mu _test-input-buffered-file _test-output-buffered-file Stderr 0)
(flush _test-output-buffered-file)
# no errors
#? # dump _test-output-stream {{{
#? (write 2 "^")
#? (write-stream 2 _test-output-stream)
#? (write 2 "$\n")
#? (rewind-stream _test-output-stream)
#? # }}}
# check output
(check-next-stream-line-equal _test-output-stream "foo:" "F - test-copy-string-literal/0")
(check-next-stream-line-equal _test-output-stream " # . prologue" "F - test-copy-string-literal/1")
(check-next-stream-line-equal _test-output-stream " 55/push-ebp" "F - test-copy-string-literal/2")
(check-next-stream-line-equal _test-output-stream " 89/<- %ebp 4/r32/esp" "F - test-copy-string-literal/3")
(check-next-stream-line-equal _test-output-stream " {" "F - test-copy-string-literal/4")
(check-next-stream-line-equal _test-output-stream "$foo:0x00000001:loop:" "F - test-copy-string-literal/5")
(check-next-stream-line-equal _test-output-stream " ff 6/subop/push %ecx" "F - test-copy-string-literal/6")
(check-next-stream-line-equal _test-output-stream " b9/copy-to-ecx \"a\"/imm32" "F - test-copy-string-literal/7")
(check-next-stream-line-equal _test-output-stream " 8f 0/subop/pop %ecx" "F - test-copy-string-literal/8")
(check-next-stream-line-equal _test-output-stream " }" "F - test-copy-string-literal/9")
(check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:" "F - test-copy-string-literal/10")
(check-next-stream-line-equal _test-output-stream " # . epilogue" "F - test-copy-string-literal/11")
(check-next-stream-line-equal _test-output-stream " 89/<- %esp 5/r32/ebp" "F - test-copy-string-literal/12")
(check-next-stream-line-equal _test-output-stream " 5d/pop-to-ebp" "F - test-copy-string-literal/13")
(check-next-stream-line-equal _test-output-stream " c3/return" "F - test-copy-string-literal/14")
# . epilogue
89/<- %esp 5/r32/ebp
5d/pop-to-ebp
c3/return
test-copy-invalid-value-to-offset:
# . prologue
55/push-ebp
@ -36256,6 +36300,9 @@ type-category: # a: (addr type-tree) -> result/eax: int
# var lit?/ecx: boolean = literal-type?(a)
(simple-mu-type? *(ebp+8) 0) # literal => eax
89/<- %ecx 0/r32/eax
# lit? |= string-literal?(a)
(simple-mu-type? *(ebp+8) 0x10) # literal-string => eax
09/or %ecx 0/r32/eax
# var float?/eax: int = float?(a)
(simple-mu-type? *(ebp+8) 0xf) # => eax
# set bits for lit? and float?