Mesa (master): Revert "glsl: Fix constant-folding for reciprocal expressions"

[Chad Versace]

Module: Mesa
Branch: master
Commit: f2e9981e43b26ca101b774ea6af1f00617098246
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=f2e9981e43b26ca101b774ea6af1f00617098246

Author: Chad Versace <chad.versace at intel.com>
Date:   Mon Feb 14 11:16:42 2011 -0800

Revert "glsl: Fix constant-folding for reciprocal expressions"

This reverts commit b3cf92aa916ee0537ee37723c23a9897ac9cd3e0.

The reverted commit prevented constant-folding of reciprocal expressions
when the reciprocated expression was 0. However, since the spec allows
division by zero, constant-folding *is* permissible in this case.

>From Section 5.9 of the GLSL 1.20 spec:
    Dividing by zero does not cause an exception but does result in an
    unspecified value.

---

 src/glsl/ir_constant_expression.cpp |   16 ++++++----------
 1 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/src/glsl/ir_constant_expression.cpp b/src/glsl/ir_constant_expression.cpp
index 2841fb3..7e00db6 100644
--- a/src/glsl/ir_constant_expression.cpp
+++ b/src/glsl/ir_constant_expression.cpp
@@ -288,24 +288,20 @@ ir_expression::constant_expression_value()
       break;
 
    case ir_unop_rcp:
-      /* FINISHME: Emit warning when division-by-zero is detected. */
       assert(op[0]->type->base_type == GLSL_TYPE_FLOAT);
       for (unsigned c = 0; c < op[0]->type->components(); c++) {
 	 switch (this->type->base_type) {
 	 case GLSL_TYPE_UINT:
-	    if (op[0]->value.u[c] == 0.0)
-	       return NULL;
-	    data.u[c] = 1 / op[0]->value.u[c];
+	    if (op[0]->value.u[c] != 0.0)
+	       data.u[c] = 1 / op[0]->value.u[c];
 	    break;
 	 case GLSL_TYPE_INT:
-	    if (op[0]->value.i[c] == 0.0)
-	       return NULL;
-	    data.i[c] = 1 / op[0]->value.i[c];
+	    if (op[0]->value.i[c] != 0.0)
+	       data.i[c] = 1 / op[0]->value.i[c];
 	    break;
 	 case GLSL_TYPE_FLOAT:
-	    if (op[0]->value.f[c] == 0.0)
-	       return NULL;
-	    data.f[c] = 1.0F / op[0]->value.f[c];
+	    if (op[0]->value.f[c] != 0.0)
+	       data.f[c] = 1.0F / op[0]->value.f[c];
 	    break;
 	 default:
 	    assert(0);