From dc637b66b25f341783efb53acc70e1bafbcba576 Mon Sep 17 00:00:00 2001 From: Eric Anholt Date: Tue, 27 Sep 2011 14:54:10 -0700 Subject: [PATCH] glsl: Add support for constant expression evaluation on round(), roundEven(). v2: Avoid the C99 rounding functions, because I don't trust get/setting the C99 rounding mode from inside our library not having other side effects. Instead, open-code roundEven() behavior around Mesa's IROUND, which we're already testing for C99 rounding mode safety. Fixes glsl-1.30/compiler/built-in-functions/round* Reviewed-by: Kenneth Graunke --- src/glsl/ir_constant_expression.cpp | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/src/glsl/ir_constant_expression.cpp b/src/glsl/ir_constant_expression.cpp index b3fe6cf9675..83f084d883d 100644 --- a/src/glsl/ir_constant_expression.cpp +++ b/src/glsl/ir_constant_expression.cpp @@ -39,6 +39,25 @@ #include "ir_visitor.h" #include "glsl_types.h" +/* Using C99 rounding functions for roundToEven() implementation is + * difficult, because round(), rint, and nearbyint() are affected by + * fesetenv(), which the application may have done for its own + * purposes. Mesa's IROUND macro is close to what we want, but it + * rounds away from 0 on n + 0.5. + */ +static int +round_to_even(float val) +{ + int rounded = IROUND(val); + + if (val - floor(val) == 0.5) { + if (rounded % 2 != 0) + rounded += val > 0 ? -1 : 1; + } + + return rounded; +} + static float dot(ir_constant *op0, ir_constant *op1) { @@ -196,6 +215,13 @@ ir_expression::constant_expression_value() } break; + case ir_unop_round_even: + assert(op[0]->type->base_type == GLSL_TYPE_FLOAT); + for (unsigned c = 0; c < op[0]->type->components(); c++) { + data.f[c] = round_to_even(op[0]->value.f[c]); + } + break; + case ir_unop_ceil: assert(op[0]->type->base_type == GLSL_TYPE_FLOAT); for (unsigned c = 0; c < op[0]->type->components(); c++) { @@ -1324,6 +1350,9 @@ ir_call::constant_expression_value() * op[1]->value.f[c]; } } + } else if (strcmp(callee, "round") == 0 || + strcmp(callee, "roundEven") == 0) { + expr = new(mem_ctx) ir_expression(ir_unop_round_even, op[0]); } else if (strcmp(callee, "sign") == 0) { expr = new(mem_ctx) ir_expression(ir_unop_sign, type, op[0], NULL); } else if (strcmp(callee, "sin") == 0) { -- 2.30.2