From 9d5554fbedcfccabdf579cb7c732747b3e8db5b9 Mon Sep 17 00:00:00 2001 From: Kartik Agaram Date: Fri, 19 Jun 2020 20:54:14 -0700 Subject: 6554 - snapshot: error on use of a clobbered var When looking up a var, ensure that it's the var most recently written to its register. The new test passes, but a handful of tests now start failing when a new var in register X is initialized based on the old var in register X. The way we do lookups is not quite right. At the moment we perform lookups when we parse words. So we look up outputs of a statement before inputs. But old bindings are still valid for the entirety of a statement, and outputs should only take effect for the next statement. --- apps/mu.subx | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 111 insertions(+), 1 deletion(-) (limited to 'apps/mu.subx') diff --git a/apps/mu.subx b/apps/mu.subx index 0bf2d25f..f596a00e 100644 --- a/apps/mu.subx +++ b/apps/mu.subx @@ -1128,6 +1128,52 @@ test-convert-function-with-second-local-var-in-same-reg: 5d/pop-to-ebp c3/return +test-read-clobbered-reg-var: + # . 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 $_test-error-buffered-file->buffer) + # var ed/edx: exit-descriptor = tailor-exit-descriptor(16) # bytes of args in call to convert-mu + 68/push 0/imm32 + 68/push 0/imm32 + 89/<- %edx 4/r32/esp + (tailor-exit-descriptor %edx 0x10) + # + (write _test-input-stream "fn foo {\n") + (write _test-input-stream " var x/ecx: int <- copy 3\n") + (write _test-input-stream " var y/ecx: int <- copy 4\n") + (write _test-input-stream " x <- increment\n") + (write _test-input-stream "}\n") + # convert + (convert-mu _test-input-buffered-file _test-output-buffered-file _test-error-buffered-file %edx) + # registers except esp clobbered at this point + # restore ed + 89/<- %edx 4/r32/esp + (flush _test-output-buffered-file) + (flush _test-error-buffered-file) +#? # dump _test-error-stream {{{ +#? (write 2 "^") +#? (write-stream 2 _test-error-stream) +#? (write 2 "$\n") +#? (rewind-stream _test-error-stream) +#? # }}} + # check output + (check-stream-equal _test-output-stream "" "F - test-read-clobbered-reg-var: output should be empty") + (check-next-stream-line-equal _test-error-stream "register ecx reads var 'x' after writing var 'y'" "F - test-read-clobbered-reg-var: error message") + # check that stop(1) was called + (check-ints-equal *(edx+4) 2 "F - test-read-clobbered-reg-var: exit status") + # don't restore from ebp + 81 0/subop/add %esp 8/imm32 + # . epilogue + 5d/pop-to-ebp + c3/return + test-convert-function-call: # . prologue 55/push-ebp @@ -7049,6 +7095,7 @@ test-parse-mu-reg-var-def: 5d/pop-to-ebp c3/return +# HERE: we push outputs on the vars stack before we read the inputs that may conflict with them parse-mu-stmt: # line: (addr stream byte), vars: (addr stack live-var), fn: (addr function), out: (addr handle stmt), err: (addr buffered-file), ed: (addr exit-descriptor) # pseudocode: # var name: slice @@ -7403,6 +7450,7 @@ $lookup-var:abort: # never gets here # return first 'name' from the top (back) of 'vars', and 0/null if not found +# ensure that 'name' if in a register is the topmost variable in that register lookup-var-helper: # name: (addr slice), vars: (addr stack live-var), out: (addr handle var), err: (addr buffered-file), ed: (addr exit-descriptor) # pseudocode: # var curr: (addr handle var) = &vars->data[vars->top - 12] @@ -7422,6 +7470,7 @@ lookup-var-helper: # name: (addr slice), vars: (addr stack live-var), out: (add 52/push-edx 53/push-ebx 56/push-esi + 57/push-edi # clear out (zero-out *(ebp+0x10) *Handle-size) # esi = vars @@ -7435,7 +7484,18 @@ lookup-var-helper: # name: (addr slice), vars: (addr stack live-var), out: (add 8d/copy-address *(esi+8) 2/r32/edx # var curr/ebx: (addr handle var) = &vars->data[vars->top - 12] 8d/copy-address *(esi+ebx-4) 3/r32/ebx # vars + 8 + vars->type - 12 + # var var-in-reg/edi: 8 addrs + 68/push 0/imm32 + 68/push 0/imm32 + 68/push 0/imm32 + 68/push 0/imm32 + 68/push 0/imm32 + 68/push 0/imm32 + 68/push 0/imm32 + 68/push 0/imm32 + 89/<- %edi 4/r32/esp { +$lookup-var-helper:loop: # if (curr < min) return 39/compare %ebx 2/r32/edx 0f 82/jump-if-addr< break/disp32 @@ -7449,6 +7509,22 @@ lookup-var-helper: # name: (addr slice), vars: (addr stack live-var), out: (add 3d/compare-eax-and 0/imm32/false { 74/jump-if-= break/disp8 +$lookup-var-helper:found: + # var vr/eax: (addr array byte) = lookup(v->register) + (lookup *(ecx+0x18) *(ecx+0x1c)) # Var-register Var-register => eax + 3d/compare-eax-and 0/imm32 + { + 74/jump-if-= break/disp8 +$lookup-var-helper:found-register: + # var reg/eax: int = get(Registers, vr) + (get Mu-registers %eax 0xc "Mu-registers") # => eax + 8b/-> *eax 0/r32/eax + # if (var-in-reg[reg]) error + 8b/-> *(edi+eax<<2) 0/r32/eax + 3d/compare-eax-and 0/imm32 + 0f 85/jump-if-!= $lookup-var-helper:error2/disp32 + } +$lookup-var-helper:return: # esi = out 8b/-> *(ebp+0x10) 6/r32/esi # *out = *curr @@ -7459,12 +7535,29 @@ lookup-var-helper: # name: (addr slice), vars: (addr stack live-var), out: (add # return eb/jump $lookup-var-helper:end/disp8 } + # 'name' not yet found; update var-in-reg if v in register + # . var vr/eax: (addr array byte) = lookup(v->register) + (lookup *(ecx+0x18) *(ecx+0x1c)) # Var-register Var-register => eax + # . if (var == 0) continue + 3d/compare-eax-and 0/imm32 + 74/jump-if-= $lookup-var-helper:continue/disp8 + # . var reg/eax: int = get(Registers, vr) + (get Mu-registers %eax 0xc "Mu-registers") # => eax + 8b/-> *eax 0/r32/eax + # . if (var-in-reg[reg] == 0) var-in-reg[reg] = v + 81 7/subop/compare *(edi+eax<<2) 0/imm32 + 75/jump-if-!= $lookup-var-helper:continue/disp8 + 89/<- *(edi+eax<<2) 1/r32/ecx +$lookup-var-helper:continue: # curr -= 12 81 5/subop/subtract %ebx 0xc/imm32 e9/jump loop/disp32 } $lookup-var-helper:end: + # . reclaim locals + 81 0/subop/add %esp 0x20/imm32 # . restore registers + 5f/pop-to-edi 5e/pop-to-esi 5b/pop-to-ebx 5a/pop-to-edx @@ -7483,6 +7576,23 @@ $lookup-var-helper:error1: (stop *(ebp+0x18) 1) # never gets here +$lookup-var-helper:error2: + # eax contains the conflicting var at this point + (write-buffered *(ebp+0x14) "register ") + 50/push-eax + (lookup *(eax+0x18) *(eax+0x1c)) # Var-register Var-register => eax + (write-buffered *(ebp+0x14) %eax) + 58/pop-to-eax + (write-buffered *(ebp+0x14) " reads var '") + (write-slice-buffered *(ebp+0x14) *(ebp+8)) + (write-buffered *(ebp+0x14) "' after writing var '") + (lookup *eax *(eax+4)) # Var-name Var-name => eax + (write-buffered *(ebp+0x14) %eax) + (write-buffered *(ebp+0x14) "'\n") + (flush *(ebp+0x14)) + (stop *(ebp+0x18) 1) + # never gets here + == data # Like Registers, but no esp or ebp Mu-registers: # (addr stream {(handle array byte), int}) @@ -7509,7 +7619,7 @@ lookup-or-define-var: # name: (addr slice), vars: (addr stack live-var), fn: (a # . save registers 50/push-eax # - (lookup-var-helper *(ebp+8) *(ebp+0xc) *(ebp+0x14)) + (lookup-var-helper *(ebp+8) *(ebp+0xc) *(ebp+0x14) *(ebp+0x18) *(ebp+0x1c)) { # if (out != 0) return 8b/-> *(ebp+0x14) 0/r32/eax -- cgit 1.4.1-2-gfad0