From: Michael D. Lowis <mike.lowis@gentex.com>
Date: Mon, 26 Jul 2021 18:34:55 +0000 (-0400)
Subject: added basic phi function handling for straight line code. Next up is if statements
X-Git-Url: https://git.mdlowis.com/?a=commitdiff_plain;h=b965041e0c7f81a3cd1d1fe8ea2951eec5cf563e;p=proto%2Fobnc.git

added basic phi function handling for straight line code. Next up is if statements
---

diff --git a/cerise/inc/cerise.h b/cerise/inc/cerise.h
index 866d583..97f6286 100644
--- a/cerise/inc/cerise.h
+++ b/cerise/inc/cerise.h
@@ -126,8 +126,21 @@ typedef struct SsaNode {
     SsaValue right;
 } SsaNode;
 
+typedef struct SsaPhiVar {
+    struct SsaPhiVar* next;
+    size_t block;
+    size_t version;
+} SsaPhiVar;
+
+typedef struct SsaPhi {
+    struct SsaPhi* next;
+    size_t symid;
+    SsaPhiVar* vars;
+} SsaPhi;
+
 typedef struct {
     size_t id;
+    SsaPhi* phis;
     SsaNode* head;
     SsaNode* tail;
 } SsaBlock;
@@ -167,7 +180,6 @@ typedef struct {
     SsaBlock* curr_block;
     SsaBlock* curr_join;
 
-
     size_t msyms;
     size_t nsyms;
     Symbol* syms;
diff --git a/cerise/src/grammar.c b/cerise/src/grammar.c
index f2dbed1..e3961db 100644
--- a/cerise/src/grammar.c
+++ b/cerise/src/grammar.c
@@ -531,7 +531,6 @@ void proc_decl(Parser* p)
     /* parse the private declarations */
     if (accept(p, CONST))
     {
-        p->curr_block = ssa_block(p);
         const_decl(p);
     }
 
@@ -626,12 +625,13 @@ static void module(Parser* p)
 
     if (accept(p, BEGIN))
     {
-//        p->curr_join = ast_block();
+        p->curr_block = ssa_block(p);
+        p->curr_join = ssa_block(p);
         if (!matches(p, END))
         {
-//            p->curr_block = ssa_block();
             SsaBlock* block = statement_seq(p);
             ssa_print_block(p, block);
+            ssa_print_block(p, p->curr_join);
             (void)block;
         }
         expect(p, END);
diff --git a/cerise/src/ssa.c b/cerise/src/ssa.c
index 9daf689..e24695b 100644
--- a/cerise/src/ssa.c
+++ b/cerise/src/ssa.c
@@ -92,6 +92,41 @@ SsaNode* ssa_op(Parser* p, int op, SsaNode* left, SsaNode* right)
         : unop(p, op, left);
 }
 
+static void phi_add(Parser* p, SsaVar var)
+{
+    /* first, append the phi function to the list */
+    SsaPhi** phis = &(p->curr_join->phis);
+    for (; *phis; phis = &((*phis)->next))
+    {
+        if ((*phis)->symid == var.symid)
+        {
+            break;
+        }
+    }
+    if (!*phis)
+    {
+        *phis = calloc(1, sizeof(SsaPhi));
+        (*phis)->symid = var.symid;
+    }
+
+    /* now add or update the variable entry */
+    SsaPhiVar** vars = &((*phis)->vars);
+    for (; *vars; vars = &((*vars)->next))
+    {
+        if ((*vars)->block == p->curr_block->id)
+        {
+            (*vars)->version = var.symver;
+            break;
+        }
+    }
+    if (!*vars)
+    {
+        *vars = calloc(1, sizeof(SsaPhiVar));
+        (*vars)->block = p->curr_block->id;
+        (*vars)->version = var.symver;
+    }
+}
+
 SsaNode* ssa_store(Parser* p, SsaNode* dest, SsaNode* value)
 {
     load(p, value);
@@ -104,6 +139,7 @@ SsaNode* ssa_store(Parser* p, SsaNode* dest, SsaNode* value)
     Symbol* sym = symbol_getbyid(p, node->dest.symid);
     sym->version++;
     node->dest.symver = sym->version;
+    phi_add(p, node->dest);
 
     ssa_block_add(p->curr_block, node);
     node->loaded = 1;
@@ -439,6 +475,23 @@ void ssa_print(Parser* p, SsaNode* expr)
 void ssa_print_block(Parser* p, SsaBlock* block)
 {
     printf("L%lu:\n", block->id);
+    for (SsaPhi* phi = block->phis; phi; phi = phi->next)
+    {
+        Symbol* s = symbol_getbyid(p, phi->symid);
+        s->version++;
+        printf("    %s.%lu = phi(", s->name, s->version);
+        for (SsaPhiVar* var = phi->vars; var; var = var->next)
+        {
+            printf("%s.%lu", s->name, var->version);
+            if (var->next)
+            {
+                printf(", ");
+            }
+        }
+        puts(")");
+    }
+
+
     for (SsaNode* node = block->head; node; node = node->next)
     {
         printf("    ");