From 6d5fe1815c96b849aaf08f31c11d9ad4fe2b4769 Mon Sep 17 00:00:00 2001 From: Ian Romanick Date: Tue, 12 Jul 2016 17:40:48 -0700 Subject: glsl: Use find_msb_uint to implement ir_unop_find_lsb (X & -X) calculates a value with only the least significant bit of X set. Since there is only one bit set, the LSB is the MSB. v2: Remove extra int() cast. Suggested by Matt. Signed-off-by: Ian Romanick Reviewed-by: Matt Turner --- src/compiler/glsl/ir_constant_expression.cpp | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/src/compiler/glsl/ir_constant_expression.cpp b/src/compiler/glsl/ir_constant_expression.cpp index 5376316d5df..a032ac6d4d5 100644 --- a/src/compiler/glsl/ir_constant_expression.cpp +++ b/src/compiler/glsl/ir_constant_expression.cpp @@ -1560,16 +1560,15 @@ ir_expression::constant_expression_value(struct hash_table *variable_context) case ir_unop_find_lsb: for (unsigned c = 0; c < components; c++) { - if (op[0]->value.i[c] == 0) - data.i[c] = -1; - else { - unsigned pos = 0; - unsigned v = op[0]->value.u[c]; - - for (; !(v & 1); v >>= 1) { - pos++; - } - data.u[c] = pos; + switch (op[0]->type->base_type) { + case GLSL_TYPE_UINT: + data.i[c] = find_msb_uint(op[0]->value.u[c] & -op[0]->value.u[c]); + break; + case GLSL_TYPE_INT: + data.i[c] = find_msb_uint(op[0]->value.i[c] & -op[0]->value.i[c]); + break; + default: + assert(0); } } break; -- cgit v1.2.3