label routines for implementing branches, jumps

src/mesa/shader/slang/slang_label.c

@@ -0,0 +1,77 @@
+
+
+/**
+ * Functions for managing instruction labels.
+ * Basically, this is used to manage the problem of forward branches where
+ * we have a branch instruciton but don't know the target address yet.
+ */
+
+
+#include "slang_label.h"
+
+
+slang_label *
+_slang_label_new(const char *name)
+{
+   slang_label *l = (slang_label *) _mesa_calloc(sizeof(slang_label));
+   if (l) {
+      l->Name = _mesa_strdup(name);
+      l->Location = -1;
+   }
+   return l;
+}
+
+void
+_slang_label_delete(slang_label *l)
+{
+   if (l->Name)
+      _mesa_free(l->Name);
+   if (l->References)
+      _mesa_free(l->References);
+   _mesa_free(l);
+}
+
+
+void
+_slang_label_add_reference(slang_label *l, GLuint inst)
+{
+   const GLuint oldSize = l->NumReferences * sizeof(GLuint);
+   assert(l->Location < 0);
+   l->References = _mesa_realloc(l->References,
+                                 oldSize, oldSize + sizeof(GLuint));
+   if (l->References) {
+      l->References[l->NumReferences] = inst;
+      l->NumReferences++;
+   }
+}
+
+
+GLint
+_slang_label_get_location(const slang_label *l)
+{
+   return l->Location;
+}
+
+
+void
+_slang_label_set_location(slang_label *l, GLint location,
+                          struct gl_program *prog)
+{
+   GLuint i;
+
+   assert(l->Location < 0);
+   assert(location >= 0);
+
+   l->Location = location;
+
+   /* for the instructions that were waiting to learn the label's location: */
+   for (i = 0; i < l->NumReferences; i++) {
+      const GLuint j = l->References[i];
+      prog->Instructions[j].BranchTarget = location;
+   }
+
+   if (l->References) {
+      _mesa_free(l->References);
+      l->References = NULL;
+   }
+}

src/mesa/shader/slang/slang_label.h

@@ -0,0 +1,42 @@
+#ifndef SLANG_LABEL_H
+#define SLANG_LABEL_H 1
+
+#include "imports.h"
+#include "mtypes.h"
+#include "prog_instruction.h"
+
+
+struct slang_label_
+{
+   char *Name;
+   GLint Location;
+   /**
+    * List of instruction references (numbered starting at zero) which need
+    * their BranchTarget field filled in with the location eventually
+    * assigned to the label.
+    */
+   GLuint NumReferences;
+   GLuint *References;   /** Array [NumReferences] */
+};
+
+typedef struct slang_label_ slang_label;
+
+
+extern slang_label *
+_slang_label_new(const char *name);
+
+extern void
+_slang_label_delete(slang_label *l);
+
+extern void
+_slang_label_add_reference(slang_label *l, GLuint inst);
+
+extern GLint
+_slang_label_get_location(const slang_label *l);
+
+extern void
+_slang_label_set_location(slang_label *l, GLint location,
+                          struct gl_program *prog);
+
+
+#endif /* SLANG_LABEL_H */