From 614eff1fc6046f728d9faced84ffedb15cb601b1 Mon Sep 17 00:00:00 2001 From: Chad Versace Date: Mon, 14 Feb 2011 13:22:39 -0800 Subject: [PATCH] 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. Signed-off-by: Ian Romanick (cherry picked from commit 62c8c773334c1b0cdd484997a4ccec8945713f8c) --- src/glsl/ir_constant_expression.cpp | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/src/glsl/ir_constant_expression.cpp b/src/glsl/ir_constant_expression.cpp index cf958aa7a17..b5850bea10e 100644 --- a/src/glsl/ir_constant_expression.cpp +++ b/src/glsl/ir_constant_expression.cpp @@ -514,10 +514,18 @@ ir_expression::constant_expression_value() switch (op[0]->type->base_type) { case GLSL_TYPE_UINT: - 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: - 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: data.f[c] = op[0]->value.f[c0] / op[1]->value.f[c1]; @@ -536,10 +544,18 @@ ir_expression::constant_expression_value() switch (op[0]->type->base_type) { case GLSL_TYPE_UINT: - 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: - 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: /* We don't use fmod because it rounds toward zero; GLSL specifies