glsl: Use a new foreach_two_lists macro for walking two lists at once.

When handling function calls, we often want to walk through the list of
formal parameters and list of actual parameters at the same time.
(Both are guaranteed to be the same length.)

Previously, we used a pattern of:

   exec_list_iterator 1st_iter = <1st list>.iterator();
   foreach_iter(exec_list_iterator, 2nd_iter, <2nd list>) {
      ...
      1st_iter.next();
   }

This was awkward, since you had to manually iterate through one of
the two lists.

This patch introduces a foreach_two_lists macro which safely walks
through two lists at the same time, so you can simply do:

   foreach_two_lists(1st_node, <1st list>, 2nd_node, <2nd list>) {
      ...
   }

v2: Rename macro from foreach_list2 to foreach_two_lists, as suggested
    by Ian Romanick.

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

12 files changed, 73 insertions, 92 deletions

diff --git a/src/glsl/ast_function.cpp b/src/glsl/ast_function.cpp
index e4c0fd1c476..2d05d072341 100644
--- a/src/glsl/ast_function.cpp
+++ b/src/glsl/ast_function.cpp
@@ -293,15 +293,10 @@ generate_call(exec_list *instructions, ir_function_signature *sig,
     * call takes place.  Since we haven't emitted the call yet, we'll place
     * the post-call conversions in a temporary exec_list, and emit them later.
     */
-   exec_list_iterator actual_iter = actual_parameters->iterator();
-   exec_list_iterator formal_iter = sig->parameters.iterator();
-
-   while (actual_iter.has_next()) {
-      ir_rvalue *actual = (ir_rvalue *) actual_iter.get();
-      ir_variable *formal = (ir_variable *) formal_iter.get();
-
-      assert(actual != NULL);
-      assert(formal != NULL);
+   foreach_two_lists(formal_node, &sig->parameters,
+                     actual_node, actual_parameters) {
+      ir_rvalue *actual = (ir_rvalue *) actual_node;
+      ir_variable *formal = (ir_variable *) formal_node;
 
       if (formal->type->is_numeric() || formal->type->is_boolean()) {
 	 switch (formal->data.mode) {
@@ -323,9 +318,6 @@ generate_call(exec_list *instructions, ir_function_signature *sig,
 	    break;
 	 }
       }
-
-      actual_iter.next();
-      formal_iter.next();
    }
 
    /* If the function call is a constant expression, don't generate any
diff --git a/src/glsl/ir.cpp b/src/glsl/ir.cpp
index 6ffa987f6d2..1a36bd631c1 100644
--- a/src/glsl/ir.cpp
+++ b/src/glsl/ir.cpp
@@ -1649,13 +1649,10 @@ modes_match(unsigned a, unsigned b)
 const char *
 ir_function_signature::qualifiers_match(exec_list *params)
 {
-   exec_list_iterator iter_a = parameters.iterator();
-   exec_list_iterator iter_b = params->iterator();
-
    /* check that the qualifiers match. */
-   while (iter_a.has_next()) {
-      ir_variable *a = (ir_variable *)iter_a.get();
-      ir_variable *b = (ir_variable *)iter_b.get();
+   foreach_two_lists(a_node, &this->parameters, b_node, params) {
+      ir_variable *a = (ir_variable *) a_node;
+      ir_variable *b = (ir_variable *) b_node;
 
       if (a->data.read_only != b->data.read_only ||
 	  !modes_match(a->data.mode, b->data.mode) ||
@@ -1666,9 +1663,6 @@ ir_function_signature::qualifiers_match(exec_list *params)
 	 /* parameter a's qualifiers don't match */
 	 return a->name;
       }
-
-      iter_a.next();
-      iter_b.next();
    }
    return NULL;
 }
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 14e2ff61062..85a4d388326 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -109,10 +109,10 @@ public:
 
    virtual ir_visitor_status visit_enter(ir_call *ir)
    {
-      exec_list_iterator sig_iter = ir->callee->parameters.iterator();
-      foreach_iter(exec_list_iterator, iter, *ir) {
-	 ir_rvalue *param_rval = (ir_rvalue *)iter.get();
-	 ir_variable *sig_param = (ir_variable *)sig_iter.get();
+      foreach_two_lists(formal_node, &ir->callee->parameters,
+                        actual_node, &ir->actual_parameters) {
+	 ir_rvalue *param_rval = (ir_rvalue *) actual_node;
+	 ir_variable *sig_param = (ir_variable *) formal_node;
 
 	 if (sig_param->data.mode == ir_var_function_out ||
 	     sig_param->data.mode == ir_var_function_inout) {
@@ -122,7 +122,6 @@ public:
 	       return visit_stop;
 	    }
 	 }
-	 sig_iter.next();
       }
 
       if (ir->return_deref != NULL) {
diff --git a/src/glsl/list.h b/src/glsl/list.h
index 5ac17cb37a4..f9eb60ec7c4 100644
--- a/src/glsl/list.h
+++ b/src/glsl/list.h
@@ -447,6 +447,22 @@ inline void exec_node::insert_before(exec_list *before)
 	; (__node)->next != NULL 			\
 	; (__node) = (__node)->next)
 
+/**
+ * Iterate through two lists at once.  Stops at the end of the shorter list.
+ *
+ * This is safe against either current node being removed or replaced.
+ */
+#define foreach_two_lists(__node1, __list1, __node2, __list2) \
+   for (exec_node * __node1 = (__list1)->head,                \
+                  * __node2 = (__list2)->head,                \
+                  * __next1 = __node1->next,                  \
+                  * __next2 = __node2->next                   \
+	; __next1 != NULL && __next2 != NULL                  \
+	; __node1 = __next1,                                  \
+          __node2 = __next2,                                  \
+          __next1 = __next1->next,                            \
+          __next2 = __next2->next)
+
 #define foreach_list_const(__node, __list)		\
    for (const exec_node * __node = (__list)->head	\
 	; (__node)->next != NULL 			\
diff --git a/src/glsl/opt_constant_folding.cpp b/src/glsl/opt_constant_folding.cpp
index 08a47b96bf7..d0e575460bd 100644
--- a/src/glsl/opt_constant_folding.cpp
+++ b/src/glsl/opt_constant_folding.cpp
@@ -122,10 +122,10 @@ ir_visitor_status
 ir_constant_folding_visitor::visit_enter(ir_call *ir)
 {
    /* Attempt to constant fold parameters */
-   exec_list_iterator sig_iter = ir->callee->parameters.iterator();
-   foreach_iter(exec_list_iterator, iter, *ir) {
-      ir_rvalue *param_rval = (ir_rvalue *)iter.get();
-      ir_variable *sig_param = (ir_variable *)sig_iter.get();
+   foreach_two_lists(formal_node, &ir->callee->parameters,
+                     actual_node, &ir->actual_parameters) {
+      ir_rvalue *param_rval = (ir_rvalue *) actual_node;
+      ir_variable *sig_param = (ir_variable *) formal_node;
 
       if (sig_param->data.mode == ir_var_function_in
           || sig_param->data.mode == ir_var_const_in) {
@@ -136,7 +136,6 @@ ir_constant_folding_visitor::visit_enter(ir_call *ir)
 	    param_rval->replace_with(new_param);
 	 }
       }
-      sig_iter.next();
    }
 
    /* Next, see if the call can be replaced with an assignment of a constant */
diff --git a/src/glsl/opt_constant_propagation.cpp b/src/glsl/opt_constant_propagation.cpp
index a2d1b0f7582..18f5da68907 100644
--- a/src/glsl/opt_constant_propagation.cpp
+++ b/src/glsl/opt_constant_propagation.cpp
@@ -281,10 +281,10 @@ ir_visitor_status
 ir_constant_propagation_visitor::visit_enter(ir_call *ir)
 {
    /* Do constant propagation on call parameters, but skip any out params */
-   exec_list_iterator sig_param_iter = ir->callee->parameters.iterator();
-   foreach_iter(exec_list_iterator, iter, ir->actual_parameters) {
-      ir_variable *sig_param = (ir_variable *)sig_param_iter.get();
-      ir_rvalue *param = (ir_rvalue *)iter.get();
+   foreach_two_lists(formal_node, &ir->callee->parameters,
+                     actual_node, &ir->actual_parameters) {
+      ir_variable *sig_param = (ir_variable *) formal_node;
+      ir_rvalue *param = (ir_rvalue *) actual_node;
       if (sig_param->data.mode != ir_var_function_out
           && sig_param->data.mode != ir_var_function_inout) {
 	 ir_rvalue *new_param = param;
@@ -294,7 +294,6 @@ ir_constant_propagation_visitor::visit_enter(ir_call *ir)
 	 else
 	    param->accept(this);
       }
-      sig_param_iter.next();
    }
 
    /* Since we're unlinked, we don't (necssarily) know the side effects of
diff --git a/src/glsl/opt_constant_variable.cpp b/src/glsl/opt_constant_variable.cpp
index 22a0fe1d107..961b8aa0660 100644
--- a/src/glsl/opt_constant_variable.cpp
+++ b/src/glsl/opt_constant_variable.cpp
@@ -132,10 +132,10 @@ 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->callee->parameters.iterator();
-   foreach_iter(exec_list_iterator, iter, *ir) {
-      ir_rvalue *param_rval = (ir_rvalue *)iter.get();
-      ir_variable *param = (ir_variable *)sig_iter.get();
+   foreach_two_lists(formal_node, &ir->callee->parameters,
+                     actual_node, &ir->actual_parameters) {
+      ir_rvalue *param_rval = (ir_rvalue *) actual_node;
+      ir_variable *param = (ir_variable *) formal_node;
 
       if (param->data.mode == ir_var_function_out ||
 	  param->data.mode == ir_var_function_inout) {
@@ -146,7 +146,6 @@ ir_constant_variable_visitor::visit_enter(ir_call *ir)
 	 entry = get_assignment_entry(var, &this->list);
 	 entry->assignment_count++;
       }
-      sig_iter.next();
    }
 
    /* Mark the return storage as having been assigned to */
diff --git a/src/glsl/opt_copy_propagation.cpp b/src/glsl/opt_copy_propagation.cpp
index 44c6f2fd3e9..195cc8baae6 100644
--- a/src/glsl/opt_copy_propagation.cpp
+++ b/src/glsl/opt_copy_propagation.cpp
@@ -185,15 +185,14 @@ ir_visitor_status
 ir_copy_propagation_visitor::visit_enter(ir_call *ir)
 {
    /* Do copy propagation on call parameters, but skip any out params */
-   exec_list_iterator sig_param_iter = ir->callee->parameters.iterator();
-   foreach_iter(exec_list_iterator, iter, ir->actual_parameters) {
-      ir_variable *sig_param = (ir_variable *)sig_param_iter.get();
-      ir_rvalue *ir = (ir_rvalue *) iter.get();
+   foreach_two_lists(formal_node, &ir->callee->parameters,
+                     actual_node, &ir->actual_parameters) {
+      ir_variable *sig_param = (ir_variable *) formal_node;
+      ir_rvalue *ir = (ir_rvalue *) actual_node;
       if (sig_param->data.mode != ir_var_function_out
           && sig_param->data.mode != ir_var_function_inout) {
          ir->accept(this);
       }
-      sig_param_iter.next();
    }
 
    /* Since we're unlinked, we don't (necessarily) know the side effects of
diff --git a/src/glsl/opt_copy_propagation_elements.cpp b/src/glsl/opt_copy_propagation_elements.cpp
index a64a9ce274f..cc53e0dd00e 100644
--- a/src/glsl/opt_copy_propagation_elements.cpp
+++ b/src/glsl/opt_copy_propagation_elements.cpp
@@ -293,15 +293,14 @@ ir_visitor_status
 ir_copy_propagation_elements_visitor::visit_enter(ir_call *ir)
 {
    /* Do copy propagation on call parameters, but skip any out params */
-   exec_list_iterator sig_param_iter = ir->callee->parameters.iterator();
-   foreach_iter(exec_list_iterator, iter, ir->actual_parameters) {
-      ir_variable *sig_param = (ir_variable *)sig_param_iter.get();
-      ir_rvalue *ir = (ir_rvalue *) iter.get();
+   foreach_two_lists(formal_node, &ir->callee->parameters,
+                     actual_node, &ir->actual_parameters) {
+      ir_variable *sig_param = (ir_variable *) formal_node;
+      ir_rvalue *ir = (ir_rvalue *) actual_node;
       if (sig_param->data.mode != ir_var_function_out
           && sig_param->data.mode != ir_var_function_inout) {
          ir->accept(this);
       }
-      sig_param_iter.next();
    }
 
    /* Since we're unlinked, we don't (necessarily) know the side effects of
diff --git a/src/glsl/opt_function_inlining.cpp b/src/glsl/opt_function_inlining.cpp
index a140ed335e0..9649598dd2b 100644
--- a/src/glsl/opt_function_inlining.cpp
+++ b/src/glsl/opt_function_inlining.cpp
@@ -116,11 +116,10 @@ ir_call::generate_inline(ir_instruction *next_ir)
     * and set up the mapping of real function body variables to ours.
     */
    i = 0;
-   exec_list_iterator sig_param_iter = this->callee->parameters.iterator();
-   exec_list_iterator param_iter = this->actual_parameters.iterator();
-   for (i = 0; i < num_parameters; i++) {
-      ir_variable *sig_param = (ir_variable *) sig_param_iter.get();
-      ir_rvalue *param = (ir_rvalue *) param_iter.get();
+   foreach_two_lists(formal_node, &this->callee->parameters,
+                     actual_node, &this->actual_parameters) {
+      ir_variable *sig_param = (ir_variable *) formal_node;
+      ir_rvalue *param = (ir_rvalue *) actual_node;
 
       /* Generate a new variable for the parameter. */
       if (sig_param->type->contains_opaque()) {
@@ -154,8 +153,7 @@ ir_call::generate_inline(ir_instruction *next_ir)
 	 next_ir->insert_before(assign);
       }
 
-      sig_param_iter.next();
-      param_iter.next();
+      ++i;
    }
 
    exec_list new_instructions;
@@ -172,11 +170,10 @@ ir_call::generate_inline(ir_instruction *next_ir)
    /* If any opaque types were passed in, replace any deref of the
     * opaque variable with a deref of the argument.
     */
-   param_iter = this->actual_parameters.iterator();
-   sig_param_iter = this->callee->parameters.iterator();
-   for (i = 0; i < num_parameters; i++) {
-      ir_rvalue *const param = (ir_rvalue *) param_iter.get();
-      ir_variable *sig_param = (ir_variable *) sig_param_iter.get();
+   foreach_two_lists(formal_node, &this->callee->parameters,
+                     actual_node, &this->actual_parameters) {
+      ir_rvalue *const param = (ir_rvalue *) actual_node;
+      ir_variable *sig_param = (ir_variable *) formal_node;
 
       if (sig_param->type->contains_opaque()) {
 	 ir_dereference *deref = param->as_dereference();
@@ -184,8 +181,6 @@ ir_call::generate_inline(ir_instruction *next_ir)
 	 assert(deref);
 	 do_variable_replacement(&new_instructions, sig_param, deref);
       }
-      param_iter.next();
-      sig_param_iter.next();
    }
 
    /* Now push those new instructions in. */
@@ -195,11 +190,10 @@ ir_call::generate_inline(ir_instruction *next_ir)
     * variables to our own.
     */
    i = 0;
-   param_iter = this->actual_parameters.iterator();
-   sig_param_iter = this->callee->parameters.iterator();
-   for (i = 0; i < num_parameters; i++) {
-      ir_rvalue *const param = (ir_rvalue *) param_iter.get();
-      const ir_variable *const sig_param = (ir_variable *) sig_param_iter.get();
+   foreach_two_lists(formal_node, &this->callee->parameters,
+                     actual_node, &this->actual_parameters) {
+      ir_rvalue *const param = (ir_rvalue *) actual_node;
+      const ir_variable *const sig_param = (ir_variable *) formal_node;
 
       /* Move our param variable into the actual param if it's an 'out' type. */
       if (parameters[i] && (sig_param->data.mode == ir_var_function_out ||
@@ -212,8 +206,7 @@ ir_call::generate_inline(ir_instruction *next_ir)
 	 next_ir->insert_before(assign);
       }
 
-      param_iter.next();
-      sig_param_iter.next();
+      ++i;
    }
 
    delete [] parameters;
diff --git a/src/glsl/opt_tree_grafting.cpp b/src/glsl/opt_tree_grafting.cpp
index 6d75a157383..f3bd580af19 100644
--- a/src/glsl/opt_tree_grafting.cpp
+++ b/src/glsl/opt_tree_grafting.cpp
@@ -204,11 +204,10 @@ ir_tree_grafting_visitor::visit_enter(ir_function_signature *ir)
 ir_visitor_status
 ir_tree_grafting_visitor::visit_enter(ir_call *ir)
 {
-   exec_list_iterator sig_iter = ir->callee->parameters.iterator();
-   /* Reminder: iterating ir_call iterates its parameters. */
-   foreach_iter(exec_list_iterator, iter, *ir) {
-      ir_variable *sig_param = (ir_variable *)sig_iter.get();
-      ir_rvalue *ir = (ir_rvalue *)iter.get();
+   foreach_two_lists(formal_node, &ir->callee->parameters,
+                     actual_node, &ir->actual_parameters) {
+      ir_variable *sig_param = (ir_variable *) formal_node;
+      ir_rvalue *ir = (ir_rvalue *) actual_node;
       ir_rvalue *new_ir = ir;
 
       if (sig_param->data.mode != ir_var_function_in
@@ -222,7 +221,6 @@ ir_tree_grafting_visitor::visit_enter(ir_call *ir)
 	 ir->replace_with(new_ir);
 	 return visit_stop;
       }
-      sig_iter.next();
    }
 
    if (ir->return_deref && check_graft(ir, ir->return_deref->var) == visit_stop)
diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index ed3715fc16e..f1b35442969 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -2617,10 +2617,10 @@ glsl_to_tgsi_visitor::visit(ir_call *ir)
    int i;
 
    /* Process in parameters. */
-   exec_list_iterator sig_iter = sig->parameters.iterator();
-   foreach_iter(exec_list_iterator, iter, *ir) {
-      ir_rvalue *param_rval = (ir_rvalue *)iter.get();
-      ir_variable *param = (ir_variable *)sig_iter.get();
+   foreach_two_lists(formal_node, &sig->parameters,
+                     actual_node, &ir->actual_parameters) {
+      ir_rvalue *param_rval = (ir_rvalue *) actual_node;
+      ir_variable *param = (ir_variable *) formal_node;
 
       if (param->data.mode == ir_var_function_in ||
           param->data.mode == ir_var_function_inout) {
@@ -2643,20 +2643,17 @@ glsl_to_tgsi_visitor::visit(ir_call *ir)
             r.index++;
          }
       }
-
-      sig_iter.next();
    }
-   assert(!sig_iter.has_next());
 
    /* Emit call instruction */
    call_inst = emit(ir, TGSI_OPCODE_CAL);
    call_inst->function = entry;
 
    /* Process out parameters. */
-   sig_iter = sig->parameters.iterator();
-   foreach_iter(exec_list_iterator, iter, *ir) {
-      ir_rvalue *param_rval = (ir_rvalue *)iter.get();
-      ir_variable *param = (ir_variable *)sig_iter.get();
+   foreach_two_lists(formal_node, &sig->parameters,
+                     actual_node, &ir->actual_parameters) {
+      ir_rvalue *param_rval = (ir_rvalue *) actual_node;
+      ir_variable *param = (ir_variable *) formal_node;
 
       if (param->data.mode == ir_var_function_out ||
           param->data.mode == ir_var_function_inout) {
@@ -2679,10 +2676,7 @@ glsl_to_tgsi_visitor::visit(ir_call *ir)
             r.index++;
          }
       }
-
-      sig_iter.next();
    }
-   assert(!sig_iter.has_next());
 
    /* Process return value. */
    this->result = entry->return_reg;