diff options
Diffstat (limited to 'src/iconc/fixcode.c')
| -rw-r--r-- | src/iconc/fixcode.c | 372 |
1 files changed, 0 insertions, 372 deletions
diff --git a/src/iconc/fixcode.c b/src/iconc/fixcode.c deleted file mode 100644 index b8c06e0..0000000 --- a/src/iconc/fixcode.c +++ /dev/null @@ -1,372 +0,0 @@ -/* - * fixcode.c - routines to "fix code" by determining what signals are returned - * by continuations and what must be done when they are. Also perform - * optional control flow optimizations. - */ -#include "../h/gsupport.h" -#include "ctrans.h" -#include "cglobals.h" -#include "ccode.h" -#include "ctree.h" -#include "csym.h" -#include "cproto.h" - -/* - * Prototypes for static functions. - */ -static struct code *ck_unneed (struct code *cd, struct code *lbl); -static void clps_brch (struct code *branch); -static void dec_refs (struct code *cd); -static void rm_unrch (struct code *cd); - -/* - * fix_fncs - go through the generated C functions, determine how calls - * handle signals, in-line trivial functions where possible, remove - * goto's which immediately precede their labels, and remove unreachable - * code. - */ -void fix_fncs(fnc) -struct c_fnc *fnc; - { - struct code *cd, *cd1; - struct code *contbody; - struct sig_act *sa; - struct sig_lst *sl; - struct code *call; - struct code *create; - struct code *ret_sig; - struct code *sig; - struct c_fnc *calledcont; - int no_break; - int collapse; - - /* - * Fix any called functions and decide how the calls handle the - * returned signals. - */ - fnc->flag |= CF_Mark; - for (call = fnc->call_lst; call != NULL; call = call->NextCall) { - calledcont = call->Cont; - if (calledcont != NULL) { - if (!(calledcont->flag & CF_Mark)) - fix_fncs(calledcont); - if (calledcont->flag & CF_ForeignSig) { - call->Flags |= ForeignSig; - fnc->flag |= CF_ForeignSig; - } - } - - - /* - * Try to collapse call chains of continuations. - */ - if (opt_cntrl && calledcont != NULL) { - contbody = calledcont->cd.next; - if (call->OperName == NULL && contbody->cd_id == C_RetSig) { - /* - * A direct call of a continuation which consists of just a - * return. Replace call with code to handle the returned signal. - */ - ret_sig = contbody->SigRef->sig; - if (ret_sig == &resume) - cd1 = sig_cd(call->ContFail, fnc); - else - cd1 = sig_cd(ret_sig, fnc); - cd1->prev = call->prev; - cd1->prev->next = cd1; - cd1->next = call->next; - if (cd1->next != NULL) - cd1->next->prev = cd1; - --calledcont->ref_cnt; - continue; /* move on to next call */ - } - else if (contbody->cd_id == C_CallSig && contbody->next == NULL) { - /* - * The called continuation contains only a call. - */ - if (call->OperName == NULL) { - /* - * We call the continuation directly, so we can in-line it. - * We must replace signal returns with appropriate actions. - */ - if (--calledcont->ref_cnt != 0 && contbody->Cont != NULL) - ++contbody->Cont->ref_cnt; - call->OperName = contbody->OperName; - call->ArgLst = contbody->ArgLst; - call->Cont = contbody->Cont; - call->Flags = contbody->Flags; - for (sa = contbody->SigActs; sa != NULL; sa = sa->next) { - ret_sig = sa->cd->SigRef->sig; - if (ret_sig == &resume) - cd1 = sig_cd(call->ContFail, fnc); - else - cd1 = sig_cd(ret_sig, fnc); - call->SigActs = new_sgact(sa->sig, cd1, call->SigActs); - } - continue; /* move on to next call */ - } - else if (contbody->OperName == NULL) { - /* - * The continuation simply calls another continuation. We can - * eliminate the intermediate continuation as long as we can - * move signal conversions to the other side of the operation. - * The operation only intercepts resume signals. - */ - collapse = 1; - for (sa = contbody->SigActs; sa != NULL; sa = sa->next) { - ret_sig = sa->cd->SigRef->sig; - if (sa->sig != ret_sig && (sa->sig == &resume || - ret_sig == &resume)) - collapse = 0; - } - if (collapse) { - if (--calledcont->ref_cnt != 0 && contbody->Cont != NULL) - ++contbody->Cont->ref_cnt; - call->Cont = contbody->Cont; - for (sa = contbody->SigActs; sa != NULL; sa = sa->next) { - ret_sig = sa->cd->SigRef->sig; - if (ret_sig != &resume) - call->SigActs = new_sgact(sa->sig, sig_cd(ret_sig, fnc), - call->SigActs); - } - continue; /* move on to next call */ - } - } - } - } - - /* - * We didn't do any optimizations. We must still figure out - * out how to handle signals returned by the continuation. - */ - if (calledcont != NULL) { - for (sl = calledcont->sig_lst; sl != NULL; sl = sl->next) { - if (sl->ref_cnt > 0) { - sig = sl->sig; - /* - * If an operation is being called, it handles failure from the - * continuation. - */ - if (sig != &resume || call->OperName == NULL) { - if (sig == &resume) - cd1 = sig_cd(call->ContFail, fnc); - else - cd1 = sig_cd(sig, fnc); - call->SigActs = new_sgact(sig, cd1, call->SigActs); - } - } - } - } - } - - /* - * fix up the signal handling in the functions implementing co-expressions. - */ - for (create = fnc->creatlst; create != NULL; create = create->NextCreat) - fix_fncs(create->Cont); - - if (!opt_cntrl) - return; /* control flow optimizations disabled. */ - /* - * Collapse branch chains and remove unreachable code. - */ - for (cd = &(fnc->cd); cd != NULL; cd = cd->next) { - switch (cd->cd_id) { - case C_CallSig: - no_break = 1; - for (sa = cd->SigActs; sa != NULL; sa = sa->next) { - if (sa->cd->cd_id == C_Break) { - switch (cd->next->cd_id) { - case C_Goto: - sa->cd->cd_id = cd->next->cd_id; - sa->cd->Lbl = cd->next->Lbl; - ++sa->cd->Lbl->RefCnt; - break; - case C_RetSig: - sa->cd->cd_id = cd->next->cd_id; - sa->cd->SigRef= cd->next->SigRef; - ++sa->cd->SigRef->ref_cnt; - break; - default: - no_break = 0; - } - } - if (sa->cd->cd_id == C_Goto) - clps_brch(sa->cd); - } - if (no_break) - rm_unrch(cd); - /* - * Try converting gotos into breaks. - */ - for (sa = cd->SigActs; sa != NULL; sa = sa->next) - if (sa->cd->cd_id == C_Goto) { - cd1 = cd->next; - while (cd1 != NULL && (cd1->cd_id == C_Label || - cd1->cd_id == C_RBrack)) { - if (cd1 == sa->cd->Lbl) { - sa->cd->cd_id = C_Break; - --cd1->RefCnt; - break; - } - cd1 = cd1->next; - } - } - break; - - case C_Goto: - clps_brch(cd); - rm_unrch(cd); - if (cd->cd_id == C_Goto) - ck_unneed(cd, cd->Lbl); - break; - - case C_If: - if (cd->ThenStmt->cd_id == C_Goto) { - clps_brch(cd->ThenStmt); - if (cd->ThenStmt->cd_id == C_Goto) - ck_unneed(cd, cd->ThenStmt->Lbl); - } - break; - - case C_PFail: - case C_PRet: - case C_RetSig: - rm_unrch(cd); - break; - } - } - - /* - * If this function only contains a return, indicate that we can - * call a shared signal returning function instead of it. This is - * a special case of "common subROUTINE elimination". - */ - if (fnc->cd.next->cd_id == C_RetSig) - fnc->flag |= CF_SigOnly; - } - -/* - * clps_brch - collapse branch chains. - */ -static void clps_brch(branch) -struct code *branch; - { - struct code *cd; - int save_id; - - cd = branch->Lbl->next; - while (cd->cd_id == C_Label) - cd = cd->next; - - /* - * Avoid infinite recursion on empty infinite loops. - */ - save_id = branch->cd_id; - branch->cd_id = 0; - if (cd->cd_id == C_Goto) - clps_brch(cd); - branch->cd_id = save_id; - - switch (cd->cd_id) { - case C_Goto: - --branch->Lbl->RefCnt; - ++cd->Lbl->RefCnt; - branch->Lbl = cd->Lbl; - break; - case C_RetSig: - /* - * This optimization requires that C_Goto have as many fields - * as C_RetSig. - */ - --branch->Lbl->RefCnt; - ++cd->SigRef->ref_cnt; - branch->cd_id = C_RetSig; - branch->SigRef = cd->SigRef; - break; - } - } - -/* - * rm_unrch - any code after the given point up to the next label is - * unreachable. Remove it. - */ -static void rm_unrch(cd) -struct code *cd; - { - struct code *cd1; - - for (cd1 = cd->next; cd1 != NULL && cd1->cd_id != C_LBrack && - (cd1->cd_id != C_Label || cd1->RefCnt == 0); cd1 = cd1->next) { - if (cd1->cd_id == C_RBrack) { - /* - * Continue deleting past a '}', but don't delete the '}' itself. - */ - cd->next = cd1; - cd1->prev = cd; - cd = cd1; - } - else - dec_refs(cd1); - } - cd->next = cd1; - if (cd1 != NULL) - cd1->prev = cd; - } - -/* - * dec_refs - decrement reference counts for things this code references. - */ -static void dec_refs(cd) -struct code *cd; - { - struct sig_act *sa; - - if (cd == NULL) - return; - switch (cd->cd_id) { - case C_Goto: - --cd->Lbl->RefCnt; - return; - case C_RetSig: - --cd->SigRef->ref_cnt; - return; - case C_CallSig: - if (cd->Cont != NULL) - --cd->Cont->ref_cnt; - for (sa = cd->SigActs; sa != NULL; sa = sa->next) - dec_refs(sa->cd); - return; - case C_If: - dec_refs(cd->ThenStmt); - return; - case C_Create: - --cd->Cont->ref_cnt; - return; - } - } - -/* - * ck_unneed - if there is nothing between a goto and its label, except - * perhaps other labels or '}', it is useless, so remove it. - */ -static struct code *ck_unneed(cd, lbl) -struct code *cd; -struct code *lbl; - { - struct code *cd1; - - cd1 = cd->next; - while (cd1 != NULL && (cd1->cd_id == C_Label || cd1->cd_id == C_RBrack)) { - if (cd1 == lbl) { - cd = cd->prev; - cd->next = cd->next->next; - cd->next->prev = cd; - --lbl->RefCnt; - break; - } - cd1 = cd1->next; - } - return cd; - } - |