Attachment 43356 Details for Bug 34160 – Patch 2/2: Fix bug

[patch] Patch 2/2: Fix bug

0002-glsl-Reinstate-constant-folding-for-division-by-zero.patch (text/plain), 3.22 KB, created by Chad Versace on 2011-02-14 13:47:02 UTC

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Creator: Chad Versace

Created: 2011-02-14 13:47:02 UTC

Size: 3.22 KB

patch

obsolete

>From 586a8fa1efe2519f5ef52a0bfe1931daf18e6b83 Mon Sep 17 00:00:00 2001
>From: Chad Versace <chad.versace@intel.com>
>Date: Mon, 14 Feb 2011 13:22:39 -0800
>Subject: [PATCH 2/2] glsl: Reinstate constant-folding for division by zero
>
>Fixes regression: https://bugs.freedesktop.org/show_bug.cgi?id=34160
>
>Commit e7c1f058d18f62aa4871aec623f994d7b68cb8c1 disabled constant-folding
>when division-by-zero occured. This was a mistake, because the spec does
>allow division by zero. (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.)
>
>For floating-point division, the original pre-e7c1f05 behavior is
>reinstated.
>
>For integer division, constant-fold 1/0 to 0.
>---
> src/glsl/ir_constant_expression.cpp |   42 +++++++++++++++++-----------------
> 1 files changed, 21 insertions(+), 21 deletions(-)
>
>diff --git a/src/glsl/ir_constant_expression.cpp b/src/glsl/ir_constant_expression.cpp
>index 7e00db6..4bc41d9 100644
>--- a/src/glsl/ir_constant_expression.cpp
>+++ b/src/glsl/ir_constant_expression.cpp
>@@ -310,13 +310,9 @@ ir_expression::constant_expression_value()
>       break;
> 
>    case ir_unop_rsq:
>-      /* 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++) {
>-	 float s = sqrtf(op[0]->value.f[c]);
>-	 if (s == 0)
>-	    return NULL;
>-	 data.f[c] = 1.0F / s;
>+	 data.f[c] = 1.0F / sqrtf(op[0]->value.f[c]);
>       }
>       break;
> 
>@@ -519,18 +515,20 @@ ir_expression::constant_expression_value()
> 
> 	 switch (op[0]->type->base_type) {
> 	 case GLSL_TYPE_UINT:
>-	    if (op[1]->value.u[c1] == 0)
>-	       return NULL;
>-	    data.u[c] = op[0]->value.u[c0] / op[1]->value.u[c1];
>+	    if (op[1]->value.u[c1] == 0) {
>+	       data.u[c] = 0;
>+	    } else {
>+	       data.u[c] = op[0]->value.u[c0] / op[1]->value.u[c1];
>+	    }
> 	    break;
> 	 case GLSL_TYPE_INT:
>-	    if (op[1]->value.i[c1] == 0)
>-	       return NULL;
>-	    data.i[c] = op[0]->value.i[c0] / op[1]->value.i[c1];
>+	    if (op[1]->value.i[c1] == 0) {
>+	       data.i[c] = 0;
>+	    } else {
>+	       data.i[c] = op[0]->value.i[c0] / op[1]->value.i[c1];
>+	    }
> 	    break;
> 	 case GLSL_TYPE_FLOAT:
>-	    if (op[1]->value.f[c1] == 0)
>-	       return NULL;
> 	    data.f[c] = op[0]->value.f[c0] / op[1]->value.f[c1];
> 	    break;
> 	 default:
>@@ -548,18 +546,20 @@ ir_expression::constant_expression_value()
> 
> 	 switch (op[0]->type->base_type) {
> 	 case GLSL_TYPE_UINT:
>-	    if (op[1]->value.u[c1] == 0)
>-	       return NULL;
>-	    data.u[c] = op[0]->value.u[c0] % op[1]->value.u[c1];
>+	    if (op[1]->value.u[c1] == 0) {
>+	       data.u[c] = 0;
>+	    } else {
>+	       data.u[c] = op[0]->value.u[c0] / op[1]->value.u[c1];
>+	    }
> 	    break;
> 	 case GLSL_TYPE_INT:
>-	    if (op[1]->value.i[c1] == 0)
>-	       return NULL;
>-	    data.i[c] = op[0]->value.i[c0] % op[1]->value.i[c1];
>+	    if (op[1]->value.i[c1] == 0) {
>+	       data.i[c] = 0;
>+	    } else {
>+	       data.i[c] = op[0]->value.i[c0] / op[1]->value.i[c1];
>+	    }
> 	    break;
> 	 case GLSL_TYPE_FLOAT:
>-	    if (op[1]->value.f[c1] == 0)
>-	       return NULL;
> 	    /* We don't use fmod because it rounds toward zero; GLSL specifies
> 	     * the use of floor.
> 	     */
>-- 
>1.7.3.5
>

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