opt: cancel out XCHG/XCHG

kspalaiologos · Jan 3, 2021 · cffca08 · cffca08
1 parent 9a2f997
commit cffca08
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Showing 2 changed files with 19 additions and 3 deletions.
diff --git a/asm_optimize.c b/asm_optimize.c
@@ -1,7 +1,15 @@
 
 #include "asm_common.h"
+
+#define INSERT_HERE(i, x) vector_insert(*data, n - vector_begin(*data) + (i), (x))
+#define ERASE_HERE(i) vector_erase(*data, n - vector_begin(*data) + (i))
+
+#define HAS(x) ((uintptr_t) (n - vector_begin(*data) - (x)) > vector_size(*data))
+
 void asm_optimize(vector(struct node_t) * data) {
-    vector_foreach(struct node_t, n, *data) {
+    for(uint32_t idx = 0; idx < vector_size(*data); idx++) {
+        struct node_t * n = (*data) + idx;
+
         switch(n->type) {
             case MUL:
                 if(n->data1.type == IMM_VALUE && n->data1.value == 2) {
@@ -10,7 +18,15 @@ void asm_optimize(vector(struct node_t) * data) {
                     n->data1.value = 0;
                     n->type = ADD;
 
-                    vector_insert(*data, n - vector_begin(*data), *n);
+                    INSERT_HERE(0, *n);
+                }
+
+                break;
+            case XCHG:
+                if(HAS(1) && n[1].type == XCHG) {
+                    // cancel out XCHG / XCHG
+                    ERASE_HERE(0);
+                    ERASE_HERE(0);
                 }
 
                 break;

diff --git a/vector.h b/vector.h
@@ -66,7 +66,7 @@
     do {                                                       \
         if (vec) {                                             \
             const size_t cv_sz = vector_size(vec);             \
-            if ((i) < cv_sz) {                                 \
+            if (((uintptr_t) (i)) < cv_sz) {                   \
                 _internal_vecsiz((vec), cv_sz - 1);            \
                 size_t cv_x;                                   \
                 for (cv_x = (i); cv_x < (cv_sz - 1); ++cv_x) { \