X-Git-Url: https://git.xonotic.org/?p=xonotic%2Fgmqcc.git;a=blobdiff_plain;f=fold.c;h=e41fd526f1207aa3894d191efc3f58c896aab8de;hp=884e039969f569e983f87a37ba3387b5893f8155;hb=73d9aa29c468a12096c0c7efc6535ffb45d85507;hpb=960cb7034af7240036a969a59f21e28e63a86df2

diff --git a/fold.c b/fold.c
index 884e039..e41fd52 100644
--- a/fold.c
+++ b/fold.c
@@ -123,15 +123,6 @@ static GMQCC_INLINE bool vec3_pbool(vec3_t a) {
     return (a.x && a.y && a.z);
 }
 
-static GMQCC_INLINE bool fold_can_1(const ast_value *val) {
-    return (ast_istype(((ast_expression*)(val)), ast_value) && val->hasvalue && (val->cvq == CV_CONST) &&
-              ((ast_expression*)(val))->vtype != TYPE_FUNCTION);
-}
-
-static GMQCC_INLINE bool fold_can_2(const ast_value *v1, const ast_value *v2) {
-    return fold_can_1(v1) && fold_can_1(v2);
-}
-
 static lex_ctx_t fold_ctx(fold_t *fold) {
     lex_ctx_t ctx;
     if (fold->parser->lex)
@@ -164,6 +155,13 @@ static GMQCC_INLINE bool fold_immediate_true(fold_t *fold, ast_value *v) {
     return !!v->constval.vfunc;
 }
 
+/* Handy macros to determine if an ast_value can be constant folded. */
+#define fold_can_1(X)  \
+    (ast_istype(((ast_expression*)(X)), ast_value) && (X)->hasvalue && ((X)->cvq == CV_CONST) && \
+                ((ast_expression*)(X))->vtype != TYPE_FUNCTION)
+
+#define fold_can_2(X, Y) (fold_can_1(X) && fold_can_1(Y))
+
 #define fold_immvalue_float(E)  ((E)->constval.vfloat)
 #define fold_immvalue_vector(E) ((E)->constval.vvec)
 #define fold_immvalue_string(E) ((E)->constval.vstring)
@@ -558,7 +556,7 @@ ast_expression *fold_op(fold_t *fold, const oper_info *info, ast_expression **op
         case 2: if(!b) return NULL;
         case 1:
         if(!a) {
-            compile_error(fold_ctx(fold), "interal error: fold_op no operands to fold\n");
+            compile_error(fold_ctx(fold), "internal error: fold_op no operands to fold\n");
             return NULL;
         }
     }
@@ -585,6 +583,59 @@ ast_expression *fold_op(fold_t *fold, const oper_info *info, ast_expression **op
         case opid2('=','='):     return fold_op_cmp    (fold, a, b, false);
         case opid2('~','P'):     return fold_op_bnot   (fold, a);
     }
-    compile_error(fold_ctx(fold), "internal error: attempted to constant for unsupported operator");
+    compile_error(fold_ctx(fold), "internal error: attempted to constant-fold for unsupported operator");
     return NULL;
 }
+
+/*
+ * These are all the actual constant folding methods that happen in between
+ * the AST/IR stage of the compiler , i.e eliminating branches for const
+ * expressions, which is the only supported thing so far. We undefine the
+ * testing macros here because an ir_value is differant than an ast_value.
+ */
+#undef isfloat
+#undef isstring
+#undef isvector
+#undef fold_immvalue_float
+#undef fold_immvalue_string
+#undef fold_immvalue_vector
+#undef fold_can_1
+#undef fold_can_2
+
+#define isfloat(X)              ((X)->vtype == TYPE_FLOAT)
+/*#define isstring(X)             ((X)->vtype == TYPE_STRING)*/
+/*#define isvector(X)             ((X)->vtype == TYPE_VECTOR)*/
+#define fold_immvalue_float(X)  ((X)->constval.vfloat)
+/*#define fold_immvalue_vector(X) ((X)->constval.vvec)*/
+/*#define fold_immvalue_string(X) ((X)->constval.vstring)*/
+#define fold_can_1(X)           ((X)->hasvalue && (X)->cvq == CV_CONST)
+/*#define fold_can_2(X,Y)         (fold_can_1(X) && fold_can_1(Y))*/
+
+
+int fold_cond(ir_value *condval, ast_function *func, ast_ifthen *branch) {
+    if (isfloat(condval) && fold_can_1(condval) && OPTS_OPTIMIZATION(OPTIM_CONST_FOLD_DCE)) {
+        ast_expression_codegen *cgen;
+        ir_block               *elide;
+        ir_value               *dummy;
+        bool                    istrue  = (fold_immvalue_float(condval) == 1.0f && branch->on_true);
+        bool                    isfalse = (fold_immvalue_float(condval) == 0.0f && branch->on_false);
+        ast_expression         *path    = (istrue)  ? branch->on_true  :
+                                          (isfalse) ? branch->on_false : NULL;
+        if (!path)
+            return false;
+        if (!(elide = ir_function_create_block(ast_ctx(branch), func->ir_func, ast_function_label(func, ((istrue) ? "ontrue" : "onfalse")))))
+            return false;
+        if (!(*(cgen = path->codegen))((ast_expression*)path, func, false, &dummy))
+            return false;
+        if (!ir_block_create_jump(func->curblock, ast_ctx(branch), elide))
+            return false;
+        /*
+         * now the branch has been eliminated and the correct block for the constant evaluation
+         * is expanded into the current block for the function.
+         */
+        func->curblock = elide;
+        ++opts_optimizationcount[OPTIM_CONST_FOLD_DCE];
+        return true;
+    }
+    return -1; /* nothing done */
+}