Mesa (11.0): glsl: Allow implicit int -> uint conversions for the % operator.

[Emil Velikov]

Module: Mesa
Branch: 11.0
Commit: 120559bd3042b8ab0eab3f0b3c3ab10594043d41
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=120559bd3042b8ab0eab3f0b3c3ab10594043d41

Author: Kenneth Graunke <kenneth at whitecape.org>
Date:   Thu Nov 12 13:02:05 2015 -0800

glsl: Allow implicit int -> uint conversions for the % operator.

GLSL 4.00 and GL_ARB_gpu_shader5 introduced a new int -> uint implicit
conversion rule and updated the rules for modulus to use them.  (In
earlier languages, none of the implicit conversion rules did anything
relevant, so there was no point in applying them.)

This allows expressions such as:

   int foo;
   uint bar;
   uint mod = foo % bar;

Cc: mesa-stable at lists.freedesktop.org
Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
(cherry picked from commit 511de1a80cedc0add386dad79cce56dd68d2f611)

---

 src/glsl/ast_to_hir.cpp |   37 ++++++++++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 9 deletions(-)

diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
index 9fdfd44..94bae57 100644
--- a/src/glsl/ast_to_hir.cpp
+++ b/src/glsl/ast_to_hir.cpp
@@ -482,18 +482,20 @@ bit_logic_result_type(const struct glsl_type *type_a,
 }
 
 static const struct glsl_type *
-modulus_result_type(const struct glsl_type *type_a,
-                    const struct glsl_type *type_b,
+modulus_result_type(ir_rvalue * &value_a, ir_rvalue * &value_b,
                     struct _mesa_glsl_parse_state *state, YYLTYPE *loc)
 {
+   const glsl_type *type_a = value_a->type;
+   const glsl_type *type_b = value_b->type;
+
    if (!state->check_version(130, 300, loc, "operator '%%' is reserved")) {
       return glsl_type::error_type;
    }
 
-   /* From GLSL 1.50 spec, page 56:
+   /* Section 5.9 (Expressions) of the GLSL 4.00 specification says:
+    *
     *    "The operator modulus (%) operates on signed or unsigned integers or
-    *    integer vectors. The operand types must both be signed or both be
-    *    unsigned."
+    *    integer vectors."
     */
    if (!type_a->is_integer()) {
       _mesa_glsl_error(loc, state, "LHS of operator %% must be an integer");
@@ -503,11 +505,28 @@ modulus_result_type(const struct glsl_type *type_a,
       _mesa_glsl_error(loc, state, "RHS of operator %% must be an integer");
       return glsl_type::error_type;
    }
-   if (type_a->base_type != type_b->base_type) {
+
+   /*    "If the fundamental types in the operands do not match, then the
+    *    conversions from section 4.1.10 "Implicit Conversions" are applied
+    *    to create matching types."
+    *
+    * Note that GLSL 4.00 (and GL_ARB_gpu_shader5) introduced implicit
+    * int -> uint conversion rules.  Prior to that, there were no implicit
+    * conversions.  So it's harmless to apply them universally - no implicit
+    * conversions will exist.  If the types don't match, we'll receive false,
+    * and raise an error, satisfying the GLSL 1.50 spec, page 56:
+    *
+    *    "The operand types must both be signed or unsigned."
+    */
+   if (!apply_implicit_conversion(type_a, value_b, state) &&
+       !apply_implicit_conversion(type_b, value_a, state)) {
       _mesa_glsl_error(loc, state,
-                       "operands of %% must have the same base type");
+                       "could not implicitly convert operands to "
+                       "modulus (%%) operator");
       return glsl_type::error_type;
    }
+   type_a = value_a->type;
+   type_b = value_b->type;
 
    /*    "The operands cannot be vectors of differing size. If one operand is
     *    a scalar and the other vector, then the scalar is applied component-
@@ -1267,7 +1286,7 @@ ast_expression::do_hir(exec_list *instructions,
       op[0] = this->subexpressions[0]->hir(instructions, state);
       op[1] = this->subexpressions[1]->hir(instructions, state);
 
-      type = modulus_result_type(op[0]->type, op[1]->type, state, & loc);
+      type = modulus_result_type(op[0], op[1], state, &loc);
 
       assert(operations[this->oper] == ir_binop_mod);
 
@@ -1514,7 +1533,7 @@ ast_expression::do_hir(exec_list *instructions,
       op[0] = this->subexpressions[0]->hir(instructions, state);
       op[1] = this->subexpressions[1]->hir(instructions, state);
 
-      type = modulus_result_type(op[0]->type, op[1]->type, state, & loc);
+      type = modulus_result_type(op[0], op[1], state, &loc);
 
       assert(operations[this->oper] == ir_binop_mod);