From: Chad Versace Date: Tue, 1 Feb 2011 17:09:33 +0000 (-0800) Subject: glsl: Fix constant-folding for reciprocal expressions X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=b3cf92aa916ee0537ee37723c23a9897ac9cd3e0;p=mesa.git glsl: Fix constant-folding for reciprocal expressions Do not constant-fold a reciprocal if any component of the reciprocated expression is 0. For example, do not constant-fold `1 / vec4(0, 1, 2, 3)`. Incorrect, previous behavior ---------------------------- Reciprocals were constant-folded even when some component of the reciprocated expression was 0. The incorrectly applied arithmetic was: 1 / 0 := 0 For example, 1 / vec4(0, 1, 2, 3) = vec4(0, 1, 1/2, 1/3) NOTE: This is a candidate for the 7.9 and 7.10 branches. --- diff --git a/src/glsl/ir_constant_expression.cpp b/src/glsl/ir_constant_expression.cpp index cf958aa7a17..321374f7f64 100644 --- a/src/glsl/ir_constant_expression.cpp +++ b/src/glsl/ir_constant_expression.cpp @@ -288,20 +288,24 @@ 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) - data.u[c] = 1 / op[0]->value.u[c]; + if (op[0]->value.u[c] == 0.0) + return NULL; + data.u[c] = 1 / op[0]->value.u[c]; break; case GLSL_TYPE_INT: - if (op[0]->value.i[c] != 0.0) - data.i[c] = 1 / op[0]->value.i[c]; + if (op[0]->value.i[c] == 0.0) + return NULL; + data.i[c] = 1 / op[0]->value.i[c]; break; case GLSL_TYPE_FLOAT: - if (op[0]->value.f[c] != 0.0) - data.f[c] = 1.0F / op[0]->value.f[c]; + if (op[0]->value.f[c] == 0.0) + return NULL; + data.f[c] = 1.0F / op[0]->value.f[c]; break; default: assert(0);