glsl: Convert ir_call to be a statement rather than a value.

Aside from ir_call, our IR is cleanly split into two classes:
- Statements (typeless; used for side effects, control flow)
- Values (deeply nestable, pure, typed expression trees)

Unfortunately, ir_call confused all this:
- For void functions, we placed ir_call directly in the instruction
  stream, treating it as an untyped statement.  Yet, it was a subclass
  of ir_rvalue, and no other ir_rvalue could be used in this way.
- For functions with a return value, ir_call could be placed in
  arbitrary expression trees.  While this fit naturally with the source
  language, it meant that expressions might not be pure, making it
  difficult to transform and optimize them.  To combat this, we always
  emitted ir_call directly in the RHS of an ir_assignment, only using
  a temporary variable in expression trees.  Many passes relied on this
  assumption; the acos and atan built-ins violated it.

This patch makes ir_call a statement (ir_instruction) rather than a
value (ir_rvalue).  Non-void calls now take a ir_dereference of a
variable, and store the return value there---effectively a call and
assignment rolled into one.  They cannot be embedded in expressions.

All expression trees are now pure, without exception.

Signed-off-by: Kenneth Graunke <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>

20 files changed, 185 insertions, 208 deletions

diff --git a/src/glsl/ast_function.cpp b/src/glsl/ast_function.cpp
index 934bc5e891a..dfdbc55c575 100644
--- a/src/glsl/ast_function.cpp
+++ b/src/glsl/ast_function.cpp
@@ -269,29 +269,21 @@ generate_call(exec_list *instructions, ir_function_signature *sig,
       formal_iter.next();
    }
 
-   /* Always insert the call in the instruction stream, and return a deref
-    * of its return val if it returns a value, since we don't know if
-    * the rvalue is going to be assigned to anything or not.
+   /* If the function call is a constant expression, don't generate any
+    * instructions; just generate an ir_constant.
     *
-    * Also insert any out parameter conversions after the call.
+    * Function calls were first allowed to be constant expressions in GLSL 1.20.
     */
-   ir_call *call = new(ctx) ir_call(sig, actual_parameters);
-   ir_dereference_variable *deref;
-   if (!sig->return_type->is_void()) {
-      /* If the function call is a constant expression, don't
-       * generate the instructions to call it; just generate an
-       * ir_constant representing the constant value.
-       *
-       * Function calls can only be constant expressions starting
-       * in GLSL 1.20.
-       */
-      if (state->language_version >= 120) {
-	 ir_constant *const_val = call->constant_expression_value();
-	 if (const_val) {
-	    return const_val;
-	 }
+   if (state->language_version >= 120) {
+      ir_constant *value = sig->constant_expression_value(actual_parameters);
+      if (value != NULL) {
+	 return value;
       }
+   }
 
+   ir_dereference_variable *deref = NULL;
+   if (!sig->return_type->is_void()) {
+      /* Create a new temporary to hold the return value. */
       ir_variable *var;
 
       var = new(ctx) ir_variable(sig->return_type,
@@ -301,18 +293,14 @@ generate_call(exec_list *instructions, ir_function_signature *sig,
       instructions->push_tail(var);
 
       deref = new(ctx) ir_dereference_variable(var);
-      ir_assignment *assign = new(ctx) ir_assignment(deref, call, NULL);
-      instructions->push_tail(assign);
-      *call_ir = call;
-
-      deref = new(ctx) ir_dereference_variable(var);
-   } else {
-      instructions->push_tail(call);
-      *call_ir = call;
-      deref = NULL;
    }
+   ir_call *call = new(ctx) ir_call(sig, deref, actual_parameters);
+   instructions->push_tail(call);
+
+   /* Also emit any necessary out-parameter conversions. */
    instructions->append_list(&post_call_conversions);
-   return deref;
+
+   return deref ? deref->clone(ctx, NULL) : NULL;
 }
 
 /**
diff --git a/src/glsl/builtins/ir/acos.ir b/src/glsl/builtins/ir/acos.ir
index d1cfebeff8a..f0078f884e7 100644
--- a/src/glsl/builtins/ir/acos.ir
+++ b/src/glsl/builtins/ir/acos.ir
@@ -2,21 +2,28 @@
    (signature float
      (parameters
        (declare (in) float x))
-     ((return (expression float - (constant float (1.5707963))
-                                  (call asin ((var_ref x)))))))
+     ((declare () float s)
+      (call asin (var_ref s) ((var_ref x)))
+      (return (expression float - (constant float (1.5707963)) (var_ref s)))))
+
    (signature vec2
      (parameters
        (declare (in) vec2 x))
-     ((return (expression vec2 - (constant float (1.5707963))
-                                 (call asin ((var_ref x)))))))
+     ((declare () vec2 s)
+      (call asin (var_ref s) ((var_ref x)))
+      (return (expression vec2 - (constant float (1.5707963)) (var_ref s)))))
+
    (signature vec3
      (parameters
        (declare (in) vec3 x))
-     ((return (expression vec3 - (constant float (1.5707963))
-                                 (call asin ((var_ref x)))))))
+     ((declare () vec3 s)
+      (call asin (var_ref s) ((var_ref x)))
+      (return (expression vec3 - (constant float (1.5707963)) (var_ref s)))))
+
    (signature vec4
      (parameters
        (declare (in) vec4 x))
-     ((return (expression vec4 - (constant float (1.5707963))
-                                 (call asin ((var_ref x)))))))
+     ((declare () vec4 s)
+      (call asin (var_ref s) ((var_ref x)))
+      (return (expression vec4 - (constant float (1.5707963)) (var_ref s)))))
 ))
diff --git a/src/glsl/builtins/ir/atan.ir b/src/glsl/builtins/ir/atan.ir
index 7b5ea13c6ba..a9dc08e9727 100644
--- a/src/glsl/builtins/ir/atan.ir
+++ b/src/glsl/builtins/ir/atan.ir
@@ -2,50 +2,62 @@
    (signature float
      (parameters
        (declare (in) float y_over_x))
-     ((return (call asin ((expression float *
+     ((declare () float s)
+      (call asin (var_ref s)
+			  ((expression float *
 			   (var_ref y_over_x)
 			   (expression float rsq
 			    (expression float +
 			     (expression float *
 			      (var_ref y_over_x)
 			      (var_ref y_over_x))
-			     (constant float (1.0))))))))))
+			     (constant float (1.0)))))))
+      (return (var_ref s))))
 
    (signature vec2
      (parameters
        (declare (in) vec2 y_over_x))
-     ((return (call asin ((expression vec2 *
+     ((declare () vec2 s)
+      (call asin (var_ref s)
+			  ((expression vec2 *
 			   (var_ref y_over_x)
 			   (expression vec2 rsq
 			    (expression vec2 +
 			     (expression vec2 *
 			      (var_ref y_over_x)
 			      (var_ref y_over_x))
-			     (constant float (1.0))))))))))
+			     (constant float (1.0)))))))
+      (return (var_ref s))))
 
    (signature vec3
      (parameters
        (declare (in) vec3 y_over_x))
-     ((return (call asin ((expression vec3 *
+     ((declare () vec3 s)
+      (call asin (var_ref s)
+			  ((expression vec3 *
 			   (var_ref y_over_x)
 			   (expression vec3 rsq
 			    (expression vec3 +
 			     (expression vec3 *
 			      (var_ref y_over_x)
 			      (var_ref y_over_x))
-			     (constant float (1.0))))))))))
+			     (constant float (1.0)))))))
+      (return (var_ref s))))
 
    (signature vec4
      (parameters
        (declare (in) vec4 y_over_x))
-     ((return (call asin ((expression vec4 *
+     ((declare () vec4 s)
+      (call asin (var_ref s)
+			  ((expression vec4 *
 			   (var_ref y_over_x)
 			   (expression vec4 rsq
 			    (expression vec4 +
 			     (expression vec4 *
 			      (var_ref y_over_x)
 			      (var_ref y_over_x))
-			     (constant float (1.0))))))))))
+			     (constant float (1.0)))))))
+      (return (var_ref s))))
 
   (signature float
     (parameters
@@ -57,7 +69,7 @@
       (if (expression bool >
            (expression float abs (var_ref x))
            (expression float * (constant float (1.0e-8)) (expression float abs (var_ref y)))) (
-        (assign (x) (var_ref r) (call atan ((expression float / (var_ref y) (var_ref x)))))
+        (call atan (var_ref r) ((expression float / (var_ref y) (var_ref x))))
         (if (expression bool < (var_ref x) (constant float (0.000000)) ) (
           (if (expression bool >= (var_ref y) (constant float (0.000000)) )
               ((assign (x) (var_ref r) (expression float + (var_ref r) (constant float (3.141593)))))
@@ -82,12 +94,11 @@
        (declare (in) vec2 y)
        (declare (in) vec2 x))
      ((declare () vec2 r)
-      (assign (x) (var_ref r)
-	      (call atan ((swiz x (var_ref y))
-			  (swiz x (var_ref x)))))
-      (assign (y) (var_ref r)
-	      (call atan ((swiz y (var_ref y))
-			  (swiz y (var_ref x)))))
+      (declare () float temp)
+      (call atan (var_ref temp) ((swiz x (var_ref y)) (swiz x (var_ref x))))
+      (assign (x) (var_ref r) (var_ref temp))
+      (call atan (var_ref temp) ((swiz y (var_ref y)) (swiz y (var_ref x))))
+      (assign (y) (var_ref r) (var_ref temp))
       (return (var_ref r))))
 
    (signature vec3
@@ -95,15 +106,13 @@
        (declare (in) vec3 y)
        (declare (in) vec3 x))
      ((declare () vec3 r)
-      (assign (x) (var_ref r)
-	      (call atan ((swiz x (var_ref y))
-			  (swiz x (var_ref x)))))
-      (assign (y) (var_ref r)
-	      (call atan ((swiz y (var_ref y))
-			  (swiz y (var_ref x)))))
-      (assign (z) (var_ref r)
-	      (call atan ((swiz z (var_ref y))
-			  (swiz z (var_ref x)))))
+      (declare () float temp)
+      (call atan (var_ref temp) ((swiz x (var_ref y)) (swiz x (var_ref x))))
+      (assign (x) (var_ref r) (var_ref temp))
+      (call atan (var_ref temp) ((swiz y (var_ref y)) (swiz y (var_ref x))))
+      (assign (y) (var_ref r) (var_ref temp))
+      (call atan (var_ref temp) ((swiz z (var_ref y)) (swiz z (var_ref x))))
+      (assign (z) (var_ref r) (var_ref temp))
       (return (var_ref r))))
 
    (signature vec4
@@ -111,18 +120,15 @@
        (declare (in) vec4 y)
        (declare (in) vec4 x))
      ((declare () vec4 r)
-      (assign (x) (var_ref r)
-	      (call atan ((swiz x (var_ref y))
-			  (swiz x (var_ref x)))))
-      (assign (y) (var_ref r)
-	      (call atan ((swiz y (var_ref y))
-			  (swiz y (var_ref x)))))
-      (assign (z) (var_ref r)
-	      (call atan ((swiz z (var_ref y))
-			  (swiz z (var_ref x)))))
-      (assign (w) (var_ref r)
-	      (call atan ((swiz w (var_ref y))
-			  (swiz w (var_ref x)))))
-      (return (var_ref r)))))
+      (declare () float temp)
+      (call atan (var_ref temp) ((swiz x (var_ref y)) (swiz x (var_ref x))))
+      (assign (x) (var_ref r) (var_ref temp))
+      (call atan (var_ref temp) ((swiz y (var_ref y)) (swiz y (var_ref x))))
+      (assign (y) (var_ref r) (var_ref temp))
+      (call atan (var_ref temp) ((swiz z (var_ref y)) (swiz z (var_ref x))))
+      (assign (z) (var_ref r) (var_ref temp))
+      (call atan (var_ref temp) ((swiz w (var_ref y)) (swiz w (var_ref x))))
+      (assign (w) (var_ref r) (var_ref temp))
+      (return (var_ref r))))
 
 ))
diff --git a/src/glsl/ir.cpp b/src/glsl/ir.cpp
index b497ff154ba..3595e742f78 100644
--- a/src/glsl/ir.cpp
+++ b/src/glsl/ir.cpp
@@ -1470,8 +1470,6 @@ ir_rvalue::error_value(void *mem_ctx)
 void
 ir_call::set_callee(ir_function_signature *sig)
 {
-   assert((this->type == NULL) || (this->type == sig->return_type));
-
    this->callee = sig;
 }
 
diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index bb4f7759b30..054e2acaadb 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -1023,16 +1023,18 @@ public:
 
 
 /**
- * IR instruction representing a function call
+ * HIR instruction representing a high-level function call, containing a list
+ * of parameters and returning a value in the supplied temporary.
  */
-class ir_call : public ir_rvalue {
+class ir_call : public ir_instruction {
 public:
-   ir_call(ir_function_signature *callee, exec_list *actual_parameters)
-      : callee(callee)
+   ir_call(ir_function_signature *callee,
+	   ir_dereference_variable *return_deref,
+	   exec_list *actual_parameters)
+      : return_deref(return_deref), callee(callee)
    {
       ir_type = ir_type_call;
       assert(callee->return_type != NULL);
-      type = callee->return_type;
       actual_parameters->move_nodes_to(& this->actual_parameters);
       this->use_builtin = callee->is_builtin;
    }
@@ -1084,9 +1086,15 @@ public:
 
    /**
     * Generates an inline version of the function before @ir,
-    * returning the return value of the function.
+    * storing the return value in return_deref.
     */
-   ir_rvalue *generate_inline(ir_instruction *ir);
+   void generate_inline(ir_instruction *ir);
+
+   /**
+    * Storage for the function's return value.
+    * This must be NULL if the return type is void.
+    */
+   ir_dereference_variable *return_deref;
 
    /* List of ir_rvalue of paramaters passed in this call. */
    exec_list actual_parameters;
diff --git a/src/glsl/ir_basic_block.cpp b/src/glsl/ir_basic_block.cpp
index a8338259620..86e0cf795a1 100644
--- a/src/glsl/ir_basic_block.cpp
+++ b/src/glsl/ir_basic_block.cpp
@@ -32,31 +32,6 @@
 #include "ir_basic_block.h"
 #include "glsl_types.h"
 
-class ir_has_call_visitor : public ir_hierarchical_visitor {
-public:
-   ir_has_call_visitor()
-   {
-      has_call = false;
-   }
-
-   virtual ir_visitor_status visit_enter(ir_call *ir)
-   {
-      (void) ir;
-      has_call = true;
-      return visit_stop;
-   }
-
-   bool has_call;
-};
-
-bool
-ir_has_call(ir_instruction *ir)
-{
-   ir_has_call_visitor v;
-   ir->accept(&v);
-   return v.has_call;
-}
-
 /**
  * Calls a user function for every basic block in the instruction stream.
  *
@@ -122,24 +97,6 @@ void call_for_basic_blocks(exec_list *instructions,
 
 	    call_for_basic_blocks(&ir_sig->body, callback, data);
 	 }
-      } else if (ir->as_assignment()) {
-	 /* If there's a call in the expression tree being assigned,
-	  * then that ends the BB too.
-	  *
-	  * The assumption is that any consumer of the basic block
-	  * walker is fine with the fact that the call is somewhere in
-	  * the tree even if portions of the tree may be evaluated
-	  * after the call.
-	  *
-	  * A consumer that has an issue with this could not process
-	  * the last instruction of the basic block.  If doing so,
-	  * expression flattener may be useful before using the basic
-	  * block finder to get more maximal basic blocks out.
-	  */
-	 if (ir_has_call(ir)) {
-	    callback(leader, ir, data);
-	    leader = NULL;
-	 }
       }
       last = ir;
    }
diff --git a/src/glsl/ir_clone.cpp b/src/glsl/ir_clone.cpp
index b6d0e8aa4a3..8a9701c9496 100644
--- a/src/glsl/ir_clone.cpp
+++ b/src/glsl/ir_clone.cpp
@@ -167,6 +167,10 @@ ir_loop::clone(void *mem_ctx, struct hash_table *ht) const
 ir_call *
 ir_call::clone(void *mem_ctx, struct hash_table *ht) const
 {
+   ir_dereference_variable *new_return_ref = NULL;
+   if (this->return_deref != NULL)
+      new_return_ref = this->return_deref->clone(mem_ctx, ht);
+
    exec_list new_parameters;
 
    foreach_iter(exec_list_iterator, iter, this->actual_parameters) {
@@ -174,7 +178,7 @@ ir_call::clone(void *mem_ctx, struct hash_table *ht) const
       new_parameters.push_tail(ir->clone(mem_ctx, ht));
    }
 
-   return new(mem_ctx) ir_call(this->callee, &new_parameters);
+   return new(mem_ctx) ir_call(this->callee, new_return_ref, &new_parameters);
 }
 
 ir_expression *
diff --git a/src/glsl/ir_constant_expression.cpp b/src/glsl/ir_constant_expression.cpp
index aa47c08d88a..4e1714a8420 100644
--- a/src/glsl/ir_constant_expression.cpp
+++ b/src/glsl/ir_constant_expression.cpp
@@ -1024,9 +1024,6 @@ ir_constant::constant_expression_value()
 ir_constant *
 ir_call::constant_expression_value()
 {
-   if (this->type == glsl_type::error_type)
-      return NULL;
-
    return this->callee->constant_expression_value(&this->actual_parameters);
 }
 
diff --git a/src/glsl/ir_expression_flattening.cpp b/src/glsl/ir_expression_flattening.cpp
index bd4ac67bc1a..b44e68ca364 100644
--- a/src/glsl/ir_expression_flattening.cpp
+++ b/src/glsl/ir_expression_flattening.cpp
@@ -29,11 +29,6 @@
  *
  * This is used for breaking down matrix operations, where it's easier to
  * create a temporary and work on each of its vector components individually.
- *
- * It is also used for automatic function inlining, where we want to take
- * an expression containing a call and move the call out to its own
- * assignment so that we can inline it at the appropriate place in the
- * instruction stream.
  */
 
 #include "ir.h"
diff --git a/src/glsl/ir_hv_accept.cpp b/src/glsl/ir_hv_accept.cpp
index c3be0521598..3ce8959245d 100644
--- a/src/glsl/ir_hv_accept.cpp
+++ b/src/glsl/ir_hv_accept.cpp
@@ -333,6 +333,14 @@ ir_call::accept(ir_hierarchical_visitor *v)
    if (s != visit_continue)
       return (s == visit_continue_with_parent) ? visit_continue : s;
 
+   if (this->return_deref != NULL) {
+      v->in_assignee = true;
+      s = this->return_deref->accept(v);
+      v->in_assignee = false;
+      if (s != visit_continue)
+	 return (s == visit_continue_with_parent) ? visit_continue : s;
+   }
+
    s = visit_list_elements(v, &this->actual_parameters, false);
    if (s == visit_stop)
       return s;
diff --git a/src/glsl/ir_print_visitor.cpp b/src/glsl/ir_print_visitor.cpp
index 78ba0ba9c81..8aa26e5d018 100644
--- a/src/glsl/ir_print_visitor.cpp
+++ b/src/glsl/ir_print_visitor.cpp
@@ -408,7 +408,10 @@ void ir_print_visitor::visit(ir_constant *ir)
 void
 ir_print_visitor::visit(ir_call *ir)
 {
-   printf("(call %s (", ir->callee_name());
+   printf("(call %s ", ir->callee_name());
+   if (ir->return_deref)
+      ir->return_deref->accept(this);
+   printf(" (");
    foreach_iter(exec_list_iterator, iter, *ir) {
       ir_instruction *const inst = (ir_instruction *) iter.get();
 
diff --git a/src/glsl/ir_reader.cpp b/src/glsl/ir_reader.cpp
index e66ae470438..7ce683ef7d3 100644
--- a/src/glsl/ir_reader.cpp
+++ b/src/glsl/ir_reader.cpp
@@ -51,11 +51,11 @@ private:
    ir_variable *read_declaration(s_expression *);
    ir_if *read_if(s_expression *, ir_loop *);
    ir_loop *read_loop(s_expression *);
+   ir_call *read_call(s_expression *);
    ir_return *read_return(s_expression *);
    ir_rvalue *read_rvalue(s_expression *);
    ir_assignment *read_assignment(s_expression *);
    ir_expression *read_expression(s_expression *);
-   ir_call *read_call(s_expression *);
    ir_swizzle *read_swizzle(s_expression *);
    ir_constant *read_constant(s_expression *);
    ir_texture *read_texture(s_expression *);
@@ -349,6 +349,8 @@ ir_reader::read_instruction(s_expression *expr, ir_loop *loop_ctx)
       inst = read_if(list, loop_ctx);
    } else if (strcmp(tag->value(), "loop") == 0) {
       inst = read_loop(list);
+   } else if (strcmp(tag->value(), "call") == 0) {
+      inst = read_call(list);
    } else if (strcmp(tag->value(), "return") == 0) {
       inst = read_return(list);
    } else if (strcmp(tag->value(), "function") == 0) {
@@ -522,8 +524,6 @@ ir_reader::read_rvalue(s_expression *expr)
       rvalue = read_swizzle(list);
    } else if (strcmp(tag->value(), "expression") == 0) {
       rvalue = read_expression(list);
-   } else if (strcmp(tag->value(), "call") == 0) {
-      rvalue = read_call(list);
    } else if (strcmp(tag->value(), "constant") == 0) {
       rvalue = read_constant(list);
    } else {
@@ -611,10 +611,20 @@ ir_reader::read_call(s_expression *expr)
 {
    s_symbol *name;
    s_list *params;
+   s_list *s_return = NULL;
 
-   s_pattern pat[] = { "call", name, params };
-   if (!MATCH(expr, pat)) {
-      ir_read_error(expr, "expected (call <name> (<param> ...))");
+   ir_dereference_variable *return_deref = NULL;
+
+   s_pattern void_pat[] = { "call", name, params };
+   s_pattern non_void_pat[] = { "call", name, s_return, params };
+   if (MATCH(expr, non_void_pat)) {
+      return_deref = read_var_ref(s_return);
+      if (return_deref == NULL) {
+	 ir_read_error(s_return, "when reading a call's return storage");
+	 return NULL;
+      }
+   } else if (!MATCH(expr, void_pat)) {
+      ir_read_error(expr, "expected (call <name> [<deref>] (<param> ...))");
       return NULL;
    }
 
@@ -644,7 +654,15 @@ ir_reader::read_call(s_expression *expr)
       return NULL;
    }
 
-   return new(mem_ctx) ir_call(callee, &parameters);
+   if (callee->return_type == glsl_type::void_type && return_deref) {
+      ir_read_error(expr, "call has return value storage but void type");
+      return NULL;
+   } else if (callee->return_type != glsl_type::void_type && !return_deref) {
+      ir_read_error(expr, "call has non-void type but no return value storage");
+      return NULL;
+   }
+
+   return new(mem_ctx) ir_call(callee, return_deref, &parameters);
 }
 
 ir_expression *
diff --git a/src/glsl/ir_validate.cpp b/src/glsl/ir_validate.cpp
index 101d9992da2..66dd84f73f3 100644
--- a/src/glsl/ir_validate.cpp
+++ b/src/glsl/ir_validate.cpp
@@ -548,6 +548,17 @@ ir_validate::visit_enter(ir_call *ir)
       abort();
    }
 
+   if (ir->return_deref) {
+      if (ir->return_deref->type != callee->return_type) {
+	 printf("callee type %s does not match return storage type %s\n",
+	        callee->return_type->name, ir->return_deref->type->name);
+	 abort();
+      }
+   } else if (callee->return_type != glsl_type::void_type) {
+      printf("ir_call has non-void callee but no return storage\n");
+      abort();
+   }
+
    const exec_node *formal_param_node = callee->parameters.head;
    const exec_node *actual_param_node = ir->actual_parameters.head;
    while (true) {
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 09ffdff63fb..d56eb97e45a 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -117,6 +117,15 @@ public:
 	 sig_iter.next();
       }
 
+      if (ir->return_deref != NULL) {
+	 ir_variable *const var = ir->return_deref->variable_referenced();
+
+	 if (strcmp(name, var->name) == 0) {
+	    found = true;
+	    return visit_stop;
+	 }
+      }
+
       return visit_continue_with_parent;
    }
 
@@ -830,6 +839,7 @@ move_non_declarations(exec_list *instructions, exec_node *last,
 	 continue;
 
       assert(inst->as_assignment()
+             || inst->as_call()
 	     || ((var != NULL) && (var->mode == ir_var_temporary)));
 
       if (make_copies) {
diff --git a/src/glsl/opt_constant_folding.cpp b/src/glsl/opt_constant_folding.cpp
index 599b21525de..db8cd5cee6d 100644
--- a/src/glsl/opt_constant_folding.cpp
+++ b/src/glsl/opt_constant_folding.cpp
@@ -117,6 +117,7 @@ ir_constant_folding_visitor::visit_enter(ir_assignment *ir)
 ir_visitor_status
 ir_constant_folding_visitor::visit_enter(ir_call *ir)
 {
+   /* Attempt to constant fold parameters */
    exec_list_iterator sig_iter = ir->get_callee()->parameters.iterator();
    foreach_iter(exec_list_iterator, iter, *ir) {
       ir_rvalue *param_rval = (ir_rvalue *)iter.get();
@@ -133,6 +134,15 @@ ir_constant_folding_visitor::visit_enter(ir_call *ir)
       sig_iter.next();
    }
 
+   /* Next, see if the call can be replaced with an assignment of a constant */
+   ir_constant *const_val = ir->constant_expression_value();
+
+   if (const_val != NULL) {
+      ir_assignment *assignment =
+	 new(ralloc_parent(ir)) ir_assignment(ir->return_deref, const_val);
+      ir->replace_with(assignment);
+   }
+
    return visit_continue_with_parent;
 }
 
diff --git a/src/glsl/opt_constant_variable.cpp b/src/glsl/opt_constant_variable.cpp
index 3fa7c3badc8..18c28018234 100644
--- a/src/glsl/opt_constant_variable.cpp
+++ b/src/glsl/opt_constant_variable.cpp
@@ -127,6 +127,7 @@ ir_constant_variable_visitor::visit_enter(ir_assignment *ir)
 ir_visitor_status
 ir_constant_variable_visitor::visit_enter(ir_call *ir)
 {
+   /* Mark any out parameters as assigned to */
    exec_list_iterator sig_iter = ir->get_callee()->parameters.iterator();
    foreach_iter(exec_list_iterator, iter, *ir) {
       ir_rvalue *param_rval = (ir_rvalue *)iter.get();
@@ -143,6 +144,17 @@ ir_constant_variable_visitor::visit_enter(ir_call *ir)
       }
       sig_iter.next();
    }
+
+   /* Mark the return storage as having been assigned to */
+   if (ir->return_deref != NULL) {
+      ir_variable *var = ir->return_deref->variable_referenced();
+      struct assignment_entry *entry;
+
+      assert(var);
+      entry = get_assignment_entry(var, &this->list);
+      entry->assignment_count++;
+   }
+
    return visit_continue;
 }
 
diff --git a/src/glsl/opt_dead_code.cpp b/src/glsl/opt_dead_code.cpp
index 22c7af1c20a..0578f1737b0 100644
--- a/src/glsl/opt_dead_code.cpp
+++ b/src/glsl/opt_dead_code.cpp
@@ -78,8 +78,7 @@ do_dead_code(exec_list *instructions, bool uniform_locations_assigned)
 	  * Don't do so if it's a shader output, though.
 	  */
 	 if (entry->var->mode != ir_var_out &&
-	     entry->var->mode != ir_var_inout &&
-	     !ir_has_call(entry->assign)) {
+	     entry->var->mode != ir_var_inout) {
 	    entry->assign->remove();
 	    progress = true;
 
diff --git a/src/glsl/opt_dead_code_local.cpp b/src/glsl/opt_dead_code_local.cpp
index 39962bd602e..a81a38fff0f 100644
--- a/src/glsl/opt_dead_code_local.cpp
+++ b/src/glsl/opt_dead_code_local.cpp
@@ -149,12 +149,7 @@ process_assignment(void *ctx, ir_assignment *ir, exec_list *assignments)
       }
    }
 
-   /* Add this instruction to the assignment list available to be removed.
-    * But not if the assignment has other side effects.
-    */
-   if (ir_has_call(ir))
-      return progress;
-
+   /* Add this instruction to the assignment list available to be removed. */
    assignment_entry *entry = new(ctx) assignment_entry(var, ir);
    assignments->push_tail(entry);
 
diff --git a/src/glsl/opt_function_inlining.cpp b/src/glsl/opt_function_inlining.cpp
index ec8b72c632f..4ff4d97d9bc 100644
--- a/src/glsl/opt_function_inlining.cpp
+++ b/src/glsl/opt_function_inlining.cpp
@@ -53,7 +53,6 @@ public:
 
    virtual ir_visitor_status visit_enter(ir_expression *);
    virtual ir_visitor_status visit_enter(ir_call *);
-   virtual ir_visitor_status visit_enter(ir_assignment *);
    virtual ir_visitor_status visit_enter(ir_return *);
    virtual ir_visitor_status visit_enter(ir_texture *);
    virtual ir_visitor_status visit_enter(ir_swizzle *);
@@ -63,23 +62,10 @@ public:
 
 
 bool
-automatic_inlining_predicate(ir_instruction *ir)
-{
-   ir_call *call = ir->as_call();
-
-   if (call && can_inline(call))
-      return true;
-
-   return false;
-}
-
-bool
 do_function_inlining(exec_list *instructions)
 {
    ir_function_inlining_visitor v;
 
-   do_expression_flattening(instructions, automatic_inlining_predicate);
-
    v.run(instructions);
 
    return v.progress;
@@ -89,12 +75,12 @@ static void
 replace_return_with_assignment(ir_instruction *ir, void *data)
 {
    void *ctx = ralloc_parent(ir);
-   ir_variable *retval = (ir_variable *)data;
+   ir_dereference *orig_deref = (ir_dereference *) data;
    ir_return *ret = ir->as_return();
 
    if (ret) {
       if (ret->value) {
-	 ir_rvalue *lhs = new(ctx) ir_dereference_variable(retval);
+	 ir_rvalue *lhs = orig_deref->clone(ctx, NULL);
 	 ret->replace_with(new(ctx) ir_assignment(lhs, ret->value, NULL));
       } else {
 	 /* un-valued return has to be the last return, or we shouldn't
@@ -106,14 +92,13 @@ replace_return_with_assignment(ir_instruction *ir, void *data)
    }
 }
 
-ir_rvalue *
+void
 ir_call::generate_inline(ir_instruction *next_ir)
 {
    void *ctx = ralloc_parent(this);
    ir_variable **parameters;
    int num_parameters;
    int i;
-   ir_variable *retval = NULL;
    struct hash_table *ht;
 
    ht = hash_table_ctor(0, hash_table_pointer_hash, hash_table_pointer_compare);
@@ -124,13 +109,6 @@ ir_call::generate_inline(ir_instruction *next_ir)
 
    parameters = new ir_variable *[num_parameters];
 
-   /* Generate storage for the return value. */
-   if (!this->callee->return_type->is_void()) {
-      retval = new(ctx) ir_variable(this->callee->return_type, "_ret_val",
-				    ir_var_auto);
-      next_ir->insert_before(retval);
-   }
-
    /* Generate the declarations for the parameters to our inlined code,
     * and set up the mapping of real function body variables to ours.
     */
@@ -185,7 +163,7 @@ ir_call::generate_inline(ir_instruction *next_ir)
       ir_instruction *new_ir = ir->clone(ctx, ht);
 
       new_instructions.push_tail(new_ir);
-      visit_tree(new_ir, replace_return_with_assignment, retval);
+      visit_tree(new_ir, replace_return_with_assignment, this->return_deref);
    }
 
    /* If any samplers were passed in, replace any deref of the sampler
@@ -238,11 +216,6 @@ ir_call::generate_inline(ir_instruction *next_ir)
    delete [] parameters;
 
    hash_table_dtor(ht);
-
-   if (retval)
-      return new(ctx) ir_dereference_variable(retval);
-   else
-      return NULL;
 }
 
 
@@ -282,13 +255,7 @@ ir_visitor_status
 ir_function_inlining_visitor::visit_enter(ir_call *ir)
 {
    if (can_inline(ir)) {
-      /* If the call was part of some tree, then it should have been
-       * flattened out or we shouldn't have seen it because of a
-       * visit_continue_with_parent in this visitor.
-       */
-      assert(ir == base_ir);
-
-      (void) ir->generate_inline(ir);
+      ir->generate_inline(ir);
       ir->remove();
       this->progress = true;
    }
@@ -297,25 +264,6 @@ ir_function_inlining_visitor::visit_enter(ir_call *ir)
 }
 
 
-ir_visitor_status
-ir_function_inlining_visitor::visit_enter(ir_assignment *ir)
-{
-   ir_call *call = ir->rhs->as_call();
-   if (!call || !can_inline(call))
-      return visit_continue;
-
-   /* generates the parameter setup, function body, and returns the return
-    * value of the function
-    */
-   ir_rvalue *rhs = call->generate_inline(ir);
-   assert(rhs);
-
-   ir->rhs = rhs;
-   this->progress = true;
-
-   return visit_continue;
-}
-
 /**
  * Replaces references to the "sampler" variable with a clone of "deref."
  *
diff --git a/src/glsl/opt_tree_grafting.cpp b/src/glsl/opt_tree_grafting.cpp
index e2aff5f8071..e70a2240fca 100644
--- a/src/glsl/opt_tree_grafting.cpp
+++ b/src/glsl/opt_tree_grafting.cpp
@@ -222,6 +222,9 @@ ir_tree_grafting_visitor::visit_enter(ir_call *ir)
       sig_iter.next();
    }
 
+   if (ir->return_deref && check_graft(ir, ir->return_deref->var) == visit_stop)
+      return visit_stop;
+
    return visit_continue;
 }