From 0b721bfa1cc4c63d366c0751f06e24f207092230 Mon Sep 17 00:00:00 2001
From: Stanislav Gromov <gromovstanislav@yandex.ru>
Date: Sat, 17 Oct 2020 16:09:44 +0800
Subject: [PATCH] Reformat struct "assigninfo" into "symstate", so it could be
 used to store multiple symbol usage flags

---
 source/compiler/sc.h  | 16 ++++++++--------
 source/compiler/sc1.c |  4 ++--
 source/compiler/sc2.c | 13 +++++++------
 3 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/source/compiler/sc.h b/source/compiler/sc.h
index 15cbd87..4d3cf54 100644
--- a/source/compiler/sc.h
+++ b/source/compiler/sc.h
@@ -302,15 +302,15 @@ typedef struct s_valuepair {
   long second;
 } valuepair;
 
-/* struct "assigninfo" is used to synchronize the status of assignments that
- * were made in multiple "if" and "switch" branches, so the compiler could
- * detect unused assignments in all of those branches, not only the last one */
+/* struct "symstate" is used to:
+ * * synchronize the status of assignments between all "if" branches or "switch"
+ *   cases, so the compiler could detect unused assignments in all of those
+ *   branches/cases, not only in the last one */
 typedef struct s_assigninfo {
-  int unused;       /* true if the variable has an unused value assigned to it
-                     * in one of the branches" */
   int lnumber;      /* line number of the first unused assignment made in one of
                      * the branches (used for error messages) */
-} assigninfo;
+  short usage;      /* usage flags to memoize (currently only uASSIGNED) */
+} symstate;
 
 /* macros for code generation */
 #define opcodes(n)      ((n)*sizeof(cell))      /* opcode size */
@@ -735,8 +735,8 @@ SC_FUNC int refer_symbol(symbol *entry,symbol *bywhom);
 SC_FUNC void markusage(symbol *sym,int usage);
 SC_FUNC void markinitialized(symbol *sym,int assignment);
 SC_FUNC void clearassignments(int fromlevel);
-SC_FUNC void memoizeassignments(int fromlevel,assigninfo **assignments);
-SC_FUNC void restoreassignments(int fromlevel,assigninfo *assignments);
+SC_FUNC void memoizeassignments(int fromlevel,symstate **assignments);
+SC_FUNC void restoreassignments(int fromlevel,symstate *assignments);
 SC_FUNC void rename_symbol(symbol *sym,const char *newname);
 SC_FUNC symbol *findglb(const char *name,int filter);
 SC_FUNC symbol *findloc(const char *name);
diff --git a/source/compiler/sc1.c b/source/compiler/sc1.c
index 85dafe7..5cba80c 100644
--- a/source/compiler/sc1.c
+++ b/source/compiler/sc1.c
@@ -5884,7 +5884,7 @@ static int doif(void)
   int ifindent;
   int lastst_true;
   int returnst=tIF;
-  assigninfo *assignments=NULL;
+  symstate *assignments=NULL;
 
   lastst=0;                     /* reset the last statement */
   ifindent=stmtindent;          /* save the indent of the "if" instruction */
@@ -6104,7 +6104,7 @@ static int doswitch(void)
   constvalue_root caselist = { NULL, NULL};   /* case list starts empty */
   constvalue *cse,*csp,*newval;
   char labelname[sNAMEMAX+1];
-  assigninfo *assignments=NULL;
+  symstate *assignments=NULL;
 
   endtok= matchtoken('(') ? ')' : tDO;
   ident=doexpr(TRUE,FALSE,FALSE,FALSE,&swtag,NULL,TRUE,NULL);   /* evaluate switch expression */
diff --git a/source/compiler/sc2.c b/source/compiler/sc2.c
index aeb6029..50523aa 100644
--- a/source/compiler/sc2.c
+++ b/source/compiler/sc2.c
@@ -3350,7 +3350,7 @@ SC_FUNC void clearassignments(int fromlevel)
 }
 
 /* memoizes all assignments done on the specified compound level and higher */
-SC_FUNC void memoizeassignments(int fromlevel,assigninfo **assignments)
+SC_FUNC void memoizeassignments(int fromlevel,symstate **assignments)
 {
   symbol *sym;
   int num;
@@ -3370,7 +3370,7 @@ SC_FUNC void memoizeassignments(int fromlevel,assigninfo **assignments)
     /* if there are no variables, then we have an early exit */
     if (num==0)
       return;
-    *assignments=(assigninfo *)calloc((size_t)num,sizeof(assigninfo));
+    *assignments=(symstate *)calloc((size_t)num,sizeof(symstate));
     if (*assignments==NULL)
       error(103); /* insufficient memory */
   } /* if */
@@ -3385,16 +3385,17 @@ SC_FUNC void memoizeassignments(int fromlevel,assigninfo **assignments)
       sym->usage &= ~uASSIGNED;
       /* memoize the assignment only if there was no other unused assignment
        * in any other "if" or "switch" branch */
-      if ((*assignments)[num].unused==FALSE) {
-        (*assignments)[num].unused=TRUE;
+      assert_static(sizeof(sym->usage)==sizeof((*assignments)->usage));
+      if (((*assignments)[num].usage & uASSIGNED)==0) {
         (*assignments)[num].lnumber=sym->lnumber;
+        (*assignments)[num].usage |= uASSIGNED;
       } /* if */
     } /* if */
   } /* for */
 }
 
 /* restores all memoized assignments */
-SC_FUNC void restoreassignments(int fromlevel,assigninfo *assignments)
+SC_FUNC void restoreassignments(int fromlevel,symstate *assignments)
 {
   symbol *sym;
   int num;
@@ -3402,7 +3403,7 @@ SC_FUNC void restoreassignments(int fromlevel,assigninfo *assignments)
   sym=&loctab;
   while ((sym=sym->next)!=NULL && sym->ident==iLABEL) {}    /* skip labels */
   for (num=0; sym!=NULL; num++,sym=sym->next) {
-    if (assignments!=NULL && assignments[num].unused) {
+    if (assignments!=NULL && (assignments[num].usage & uASSIGNED)!=0) {
       sym->usage |= uASSIGNED;
       sym->lnumber=assignments[num].lnumber;
     } /* if */