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Fix a bug that was causing the code generator to loose

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code_exprn.m:
	Fix a bug that was causing the code generator to loose
	track of how many references there are to a register.
	The bug was what caused incorrect results for one of
	Bart's programs.
This commit is contained in:
Thomas Conway
1995-04-30 10:12:37 +00:00
parent a5e5eb5503
commit 57e3bc01db
1 changed files with 30 additions and 24 deletions
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54
compiler/code_exprn.m
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@@ -792,7 +792,9 @@ code_exprn__place_var_2(cached(Exprn0), Var, Lval, Code) -->
{ code_exprn__expr_is_constant(Exprn0, Vars0, NLG, ASM, Exprn) } { code_exprn__expr_is_constant(Exprn0, Vars0, NLG, ASM, Exprn) }
-> ->
% move stuff out of the way % move stuff out of the way
code_exprn__clear_lval(Lval, ClearCode), % We don't care about the renamed exprn
% because it is a constant
code_exprn__clear_lval(Lval, Exprn, _Exprn, ClearCode),
% reserve the register % reserve the register
code_exprn__add_lval_reg_dependencies(Lval), code_exprn__add_lval_reg_dependencies(Lval),
{ set__list_to_set([Exprn, lval(Lval)], Rvals) }, { set__list_to_set([Exprn, lval(Lval)], Rvals) },
@@ -804,24 +806,24 @@ code_exprn__place_var_2(cached(Exprn0), Var, Lval, Code) -->
]) } ]) }
; ;
% move stuff out of the way % move stuff out of the way
code_exprn__clear_lval(Lval, ClearCode), code_exprn__clear_lval(Lval, Exprn0, Exprn1, ClearCode),
% reserve the register % reserve the register
code_exprn__add_lval_reg_dependencies(Lval), code_exprn__add_lval_reg_dependencies(Lval),
{ exprn_aux__vars_in_rval(Exprn0, VarList) }, { exprn_aux__vars_in_rval(Exprn1, VarList) },
code_exprn__produce_vars(VarList, VarLocList, Code0), code_exprn__produce_vars(VarList, VarLocList, Code0),
code_exprn__rem_rval_reg_dependencies(Exprn0), code_exprn__rem_rval_reg_dependencies(Exprn1),
{ exprn_aux__substitute_vars_in_rval(VarLocList, { exprn_aux__substitute_vars_in_rval(VarLocList,
Exprn0, Exprn1) }, Exprn1, Exprn2) },
( (
{ Exprn1 = create(_, _, _) } { Exprn2 = create(_, _, _) }
-> ->
code_exprn__get_var_rvals(Var, Rvals7), code_exprn__get_var_rvals(Var, Rvals7),
{ set__to_sorted_list(Rvals7, RvalList7) }, { set__to_sorted_list(Rvals7, RvalList7) },
{ code_exprn__select_rval(RvalList7, Exprn2) }, { code_exprn__select_rval(RvalList7, Exprn3) },
{ exprn_aux__substitute_vars_in_rval(VarLocList, { exprn_aux__substitute_vars_in_rval(VarLocList,
Exprn2, Exprn) } Exprn3, Exprn) }
; ;
{ Exprn = Exprn1 } { Exprn = Exprn2 }
), ),
code_exprn__add_rval_reg_dependencies(Exprn), code_exprn__add_rval_reg_dependencies(Exprn),
{ set__list_to_set([Exprn, lval(Lval)], Rvals) }, { set__list_to_set([Exprn, lval(Lval)], Rvals) },
@@ -848,17 +850,17 @@ code_exprn__place_var_2(evaled(Rvals0), Var, Lval, Code) -->
{ Stat = evaled(Rvals0) } { Stat = evaled(Rvals0) }
; ;
{ set__to_sorted_list(Rvals0, RvalList) }, { set__to_sorted_list(Rvals0, RvalList) },
{ code_exprn__select_rval(RvalList, Rval) }, { code_exprn__select_rval(RvalList, Rval0) },
{ {
Rval = lval(reg(_)) Rval0 = lval(reg(_))
; ;
Rval = lval(stackvar(_)) Rval0 = lval(stackvar(_))
; ;
Rval = lval(framevar(_)) Rval0 = lval(framevar(_))
} }
-> ->
% move stuff out of the way % move stuff out of the way
code_exprn__clear_lval(Lval, ClearCode), code_exprn__clear_lval(Lval, Rval0, Rval, ClearCode),
% reserve the register % reserve the register
code_exprn__add_lval_reg_dependencies(Lval), code_exprn__add_lval_reg_dependencies(Lval),
code_exprn__get_var_rvals(Var, Rvals1), code_exprn__get_var_rvals(Var, Rvals1),
@@ -869,10 +871,10 @@ code_exprn__place_var_2(evaled(Rvals0), Var, Lval, Code) -->
{ code_exprn__construct_code(Lval, VarName, Rval, ExprnCode) } { code_exprn__construct_code(Lval, VarName, Rval, ExprnCode) }
; ;
{set__to_sorted_list(Rvals0, RvalList0) }, {set__to_sorted_list(Rvals0, RvalList0) },
{ code_exprn__member_expr_is_constant(RvalList0, Vars0, NLG, ASM, Rval1) } { code_exprn__member_expr_is_constant(RvalList0, Vars0, NLG, ASM, Rval0) }
-> ->
% move stuff out of the way % move stuff out of the way
code_exprn__clear_lval(Lval, ClearCode), code_exprn__clear_lval(Lval, Rval0, Rval1, ClearCode),
% reserve the register % reserve the register
code_exprn__add_lval_reg_dependencies(Lval), code_exprn__add_lval_reg_dependencies(Lval),
code_exprn__get_var_rvals(Var, Rvals1), code_exprn__get_var_rvals(Var, Rvals1),
@@ -884,10 +886,6 @@ code_exprn__place_var_2(evaled(Rvals0), Var, Lval, Code) -->
assign(Lval, Rval1) - Comment assign(Lval, Rval1) - Comment
]) } ]) }
; ;
% move stuff out of the way
code_exprn__clear_lval(Lval, ClearCode),
% reserve the register
code_exprn__add_lval_reg_dependencies(Lval),
% choose one of the rvals from % choose one of the rvals from
% the old set, to avoid the % the old set, to avoid the
% potential issue-slot conflict % potential issue-slot conflict
@@ -895,7 +893,11 @@ code_exprn__place_var_2(evaled(Rvals0), Var, Lval, Code) -->
% which is non-atomic so we must % which is non-atomic so we must
% choose from the new set. % choose from the new set.
{ set__to_sorted_list(Rvals0, RvalList) }, { set__to_sorted_list(Rvals0, RvalList) },
{ code_exprn__select_rval(RvalList, Rval1) }, { code_exprn__select_rval(RvalList, Rval0) },
% move stuff out of the way
code_exprn__clear_lval(Lval, Rval0, Rval1, ClearCode),
% reserve the register
code_exprn__add_lval_reg_dependencies(Lval),
( (
{ Rval1 = create(_, _, _) } { Rval1 = create(_, _, _) }
-> ->
@@ -921,10 +923,11 @@ code_exprn__place_var_2(evaled(Rvals0), Var, Lval, Code) -->
%------------------------------------------------------------------------------% %------------------------------------------------------------------------------%
:- pred code_exprn__clear_lval(lval, code_tree, exprn_info, exprn_info). :- pred code_exprn__clear_lval(lval, rval, rval,
:- mode code_exprn__clear_lval(in, out, in, out) is det. code_tree, exprn_info, exprn_info).
:- mode code_exprn__clear_lval(in, in, out, out, in, out) is det.
code_exprn__clear_lval(Lval, Code) --> code_exprn__clear_lval(Lval, Rval0, Rval, Code) -->
( (
code_exprn__get_vars(Vars0), code_exprn__get_vars(Vars0),
{ code_exprn__lval_in_use(Lval, Vars0) } { code_exprn__lval_in_use(Lval, Vars0) }
@@ -934,11 +937,14 @@ code_exprn__clear_lval(Lval, Code) -->
code_exprn__relocate_lval(VarsList0, Lval, reg(Reg), VarsList), code_exprn__relocate_lval(VarsList0, Lval, reg(Reg), VarsList),
{ map__from_assoc_list(VarsList, Vars) }, { map__from_assoc_list(VarsList, Vars) },
code_exprn__set_vars(Vars), code_exprn__set_vars(Vars),
{ exprn_aux__substitute_lval_in_rval(Lval, reg(Reg),
Rval0, Rval) },
{ Code = node([ { Code = node([
assign(reg(Reg), lval(Lval)) - assign(reg(Reg), lval(Lval)) -
"shuffle lval" "shuffle lval"
]) } ]) }
; ;
{ Rval = Rval0 },
{ Code = empty } { Code = empty }
). ).