From: David Given <dg@cowlark.com>
Date: Sat, 21 Jan 2017 19:51:32 +0000 (+0100)
Subject: We now allocate fake registers! Although it's broken and needs reworking.
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=27dfbc08b84cacf3460ba4d313ebe02715631d1f;p=ack.git

We now allocate fake registers! Although it's broken and needs reworking.
---

diff --git a/mach/proto/mcg/hop.c b/mach/proto/mcg/hop.c
index eaf5baf77..4753bf99d 100644
--- a/mach/proto/mcg/hop.c
+++ b/mach/proto/mcg/hop.c
@@ -233,6 +233,20 @@ static char* appendf(const char* fmt, ...)
     return p;
 }
 
+static struct vreg* actual(struct vreg* vreg)
+{
+    while (vreg->coalesced_with)
+        vreg = vreg->coalesced_with;
+    return vreg;
+}
+
+void appendvreg(struct vreg* vreg)
+{
+    appendf("%%%d=%d", vreg->id, vreg->hreg);
+    if (vreg->is_spilt)
+        appendf("S");
+}
+
 void appendvalue(struct hop* hop, struct value* value)
 {
     struct valueusage* usage = hop_get_value_usage(hop, value);
@@ -255,7 +269,7 @@ void appendvalue(struct hop* hop, struct value* value)
     }
 
     if (vreg)
-        appendf("%%%d", vreg->id);
+        appendvreg(actual(vreg));
     else
         appendf("$%d:%d", value->ir->id, value->subid);
 }
@@ -303,6 +317,26 @@ char* hop_render(struct hop* hop)
     bufferlen = 0;
 	buffer[0] = '\0';
 
+    if (hop->is_move)
+    {
+        struct hashtable_iterator hit = {};
+        appendf("@move:");
+        while (hashtable_next(hop->valueusage, &hit))
+        {
+            struct valueusage* usage = hit.value;
+            struct vreg* left = actual(usage->invreg);
+            struct vreg* right = actual(usage->outvreg);
+            if (left != right)
+            {
+                appendf(" ");
+                appendvreg(usage->invreg);
+                appendf("->");
+                appendvreg(usage->outvreg);
+            }
+        }
+        appendf("\n");
+    }
+
     if (hop->pseudo)
         appendf("@");
 
diff --git a/mach/proto/mcg/pass_assignvregs.c b/mach/proto/mcg/pass_assignvregs.c
index 88d882006..4238cf293 100644
--- a/mach/proto/mcg/pass_assignvregs.c
+++ b/mach/proto/mcg/pass_assignvregs.c
@@ -10,6 +10,7 @@ static struct vreg* create_vreg(struct value* value)
     struct vreg* vreg = heap_alloc(&proc_heap, 1, sizeof(*vreg));
     vreg->id = vregcount++;
     vreg->value = value;
+    vreg->hreg = -1;
     return vreg;
 }
 
diff --git a/mach/proto/mcg/pass_registerallocator.c b/mach/proto/mcg/pass_registerallocator.c
index 05f48e303..15c19e474 100644
--- a/mach/proto/mcg/pass_registerallocator.c
+++ b/mach/proto/mcg/pass_registerallocator.c
@@ -1,6 +1,7 @@
 #include "mcg.h"
 #include "bigraph.h"
 #include "set.h"
+#include "bitmap.h"
 #include <limits.h>
 
 /* This is based around the elegant graph colouring algorithm here:
@@ -20,12 +21,13 @@ static struct vreg* actual(struct vreg* vreg)
     return vreg;
 }
 
-static void coalesce(struct vreg* v1, struct vreg* v2)
+static void coalesce(struct vreg* vmaster, struct vreg* vslave)
 {
-    tracef('R', "R: coalescing %%%d into %%%d\n", v1->id, v2->id);
-    v1 = actual(v1);
-    v2 = actual(v2);
-    v1->coalesced_with = v2;
+    vmaster = actual(vmaster);
+    vslave = actual(vslave);
+    bitmap_or(&vmaster->bitmap, 32, &vslave->bitmap);
+    vmaster->needs_register |= vslave->needs_register;
+    vslave->coalesced_with = vmaster;
 }
 
 static void wire_together_bbs(void)
@@ -144,8 +146,8 @@ static void dump_interference_graph(void)
 
 static bool attempt_to_coalesce(void)
 {
-    struct vreg* v1 = NULL;
-    struct vreg* v2 = NULL;
+    struct vreg* vmaster = NULL;
+    struct vreg* vslave = NULL;
     int degree = INT_MAX;
 
     /* Find the affinity edge with the lowest interference degree. */
@@ -166,41 +168,124 @@ static bool attempt_to_coalesce(void)
 
             if (combined.count < degree)
             {
-                v1 = left;
-                v2 = right;
+                vmaster = left;
+                vslave = right;
                 degree = combined.count;
             }
         }
     }
 
-    if (!v1)
-        return false;
-    if (degree > DEGREE)
+    if (!vmaster || (degree > DEGREE))
         return false;
 
     tracef('R', "R: coalescing affinity edge: %%%d->%%%d, degree %d\n",
-        v1->id, v2->id, degree);
-    coalesce(v1, v2);
+        vmaster->id, vslave->id, degree);
+    coalesce(vmaster, vslave);
 
-    graph_merge_vertices(&affinity, v1, v2);
-    if (graph_get_vertex_degree(&affinity, v1) == 0)
-        graph_remove_vertex(&affinity, v1);
+    graph_merge_vertices(&affinity, vmaster, vslave);
+    if (graph_get_vertex_degree(&affinity, vslave) == 0)
+        graph_remove_vertex(&affinity, vslave);
 
-    graph_merge_vertices(&interference, v1, v2);
+    graph_merge_vertices(&interference, vmaster, vslave);
 
     return true;
 }
 
 static bool attempt_to_simplify(void)
 {
-    return false;
+    struct vreg* vreg = NULL;
+    int degree = INT_MAX;
+
+    /* Find the vreg with the lowest degree that's not move-related (i.e.
+     * has no affinity edges). */
+
+    {
+        struct vertex_iterator vit = {};
+        while (graph_next_vertex(&interference, &vit))
+        {
+            struct vreg* v = vit.data;
+            if (graph_get_vertex_degree(&affinity, v) == 0)
+            {
+                int d = graph_get_vertex_degree(&interference, v);
+                if (d < degree)
+                {
+                    vreg = v;
+                    degree = d;
+                }
+            }
+        }
+    }
+
+    if (!vreg || (degree > DEGREE))
+        return false;
+
+    /* Allocate a register. */
+
+    vreg->hreg = bitmap_find_unset_bit(&vreg->bitmap, 32);
+    tracef('R', "R: simplifying vreg %%%d with degree %d and bitmap 0x%x to hreg %d\n",
+        vreg->id, degree, vreg->bitmap, vreg->hreg);
+    {
+        struct neighbour_iterator nit = {};
+        while (graph_next_neighbour(&interference, vreg, &nit))
+        {
+            struct vreg* neighbour = nit.data;
+            bitmap_set(&neighbour->bitmap, 32, vreg->hreg);
+        }
+    }
+
+    /* ...and remove it from the graph. */
+
+    graph_remove_vertex(&interference, vreg);
+    graph_remove_vertex(&affinity, vreg);
+
+    return true;
+}
+
+static bool attempt_to_spill(void)
+{
+    struct vreg* vreg = NULL;
+    int degree = INT_MIN;
+
+    /* Find the spillable vreg with the *highest* degree. */
+
+    {
+        struct vertex_iterator vit = {};
+        while (graph_next_vertex(&interference, &vit))
+        {
+            struct vreg* v = vit.data;
+            if (!v->needs_register)
+            {
+                int d = graph_get_vertex_degree(&interference, v);
+                if (d > degree)
+                {
+                    vreg = v;
+                    degree = d;
+                }
+            }
+        }
+    }
+
+    if (!vreg)
+        return false;
+
+    tracef('R', "R: spilling vreg %%%d with degree %d\n",
+        vreg->id, degree);
+    vreg->is_spilt = true;
+
+    /* ...and remove it from the graph. */
+
+    graph_remove_vertex(&interference, vreg);
+    graph_remove_vertex(&affinity, vreg);
+
+    return true;
 }
 
+
 static void iterate(void)
 {
     struct anode* spill;
 
-    while (true)
+    while (interference.vertices.size > 0)
     {
         tracef('R', "R: iterating; interference graph: %d, affinity graph: %d\n",
             interference.edges.table.size, affinity.edges.table.size);
@@ -211,10 +296,10 @@ static void iterate(void)
         if (attempt_to_simplify())
             continue;
 
-        // if (attempt_to_spill_or_simplify())
-        //     continue;
+        if (attempt_to_spill())
+             continue;
 
-        break;
+        fatal("unable to allocate registers!");
     }
 }
 
@@ -223,9 +308,8 @@ void pass_register_allocator(void)
     wire_together_bbs();
     generate_graph();
 
-    //iterate();
-
     dump_interference_graph();
+    iterate();
 
     graph_reset(&interference);
     graph_reset(&affinity);
diff --git a/mach/proto/mcg/procedure.c b/mach/proto/mcg/procedure.c
index 82160727d..100bbb44a 100644
--- a/mach/proto/mcg/procedure.c
+++ b/mach/proto/mcg/procedure.c
@@ -228,10 +228,10 @@ void procedure_compile(struct procedure* proc)
 #if 0
     pass_add_prologue_epilogue();
     print_hops('9');
+#endif
 
     emit_procedure(proc);
 
-#endif
     heap_free(&proc_heap);
 }
 
diff --git a/mach/proto/mcg/reg.h b/mach/proto/mcg/reg.h
index d8e4053e1..cc5868dfa 100644
--- a/mach/proto/mcg/reg.h
+++ b/mach/proto/mcg/reg.h
@@ -18,7 +18,10 @@ struct vreg
     int id;
     struct value* value;
     struct vreg* coalesced_with;
+    int hreg;
+    unsigned int bitmap;
     bool needs_register;
+    bool is_spilt;
 };
 
 extern struct hreg* new_hreg(const struct burm_register_data* brd);