On Mon, Apr 15, 2013 at 1:09 AM, Vadim Girlin <vadimgir...@gmail.com> wrote:
> On 04/15/2013 01:05 AM, Martin Andersson wrote:
>>
>> There is a bug where a BREAK/CONTINUE followed by LOOP_STARTxxx for nested
>> loops may put the branch stack into a state such that ALU_PUSH_BEFORE
>> doesn't work as expected. Workaround this by replacing the ALU_PUSH_BEFORE
>> with a PUSH + ALU for nested loops.
>>
>> Fixes piglit tests:
>> spec/!OpenGL 1.1/read-front
>> spec/EXT_transform_feedback/order*
>> spec/glsl-1.40/uniform_buffer/fs-struct-pad
>>
>> No piglit regressions.
>> ---
>> src/gallium/drivers/r600/r600_shader.c | 33
>> ++++++++++++++++++++++++++++++---
>> 1 file changed, 30 insertions(+), 3 deletions(-)
>>
>> diff --git a/src/gallium/drivers/r600/r600_shader.c
>> b/src/gallium/drivers/r600/r600_shader.c
>> index 6dbca50..aee011e 100644
>> --- a/src/gallium/drivers/r600/r600_shader.c
>> +++ b/src/gallium/drivers/r600/r600_shader.c
>> @@ -252,6 +252,7 @@ static int tgsi_endif(struct r600_shader_ctx *ctx);
>> static int tgsi_bgnloop(struct r600_shader_ctx *ctx);
>> static int tgsi_endloop(struct r600_shader_ctx *ctx);
>> static int tgsi_loop_brk_cont(struct r600_shader_ctx *ctx);
>> +static bool need_cayman_loop_bug_workaround(struct r600_shader_ctx *ctx);
>>
>> /*
>> * bytestream -> r600 shader
>> @@ -5490,7 +5491,7 @@ static int tgsi_opdst(struct r600_shader_ctx *ctx)
>> return 0;
>> }
>>
>> -static int emit_logic_pred(struct r600_shader_ctx *ctx, int opcode)
>> +static int emit_logic_pred(struct r600_shader_ctx *ctx, int opcode, int
>> alu_type)
>> {
>> struct r600_bytecode_alu alu;
>> int r;
>> @@ -5510,7 +5511,7 @@ static int emit_logic_pred(struct r600_shader_ctx
>> *ctx, int opcode)
>>
>> alu.last = 1;
>>
>> - r = r600_bytecode_add_alu_type(ctx->bc, &alu,
>> CF_OP_ALU_PUSH_BEFORE);
>> + r = r600_bytecode_add_alu_type(ctx->bc, &alu, alu_type);
>> if (r)
>> return r;
>> return 0;
>> @@ -5730,7 +5731,20 @@ static void break_loop_on_flag(struct
>> r600_shader_ctx *ctx, unsigned fc_sp)
>>
>> static int tgsi_if(struct r600_shader_ctx *ctx)
>> {
>> - emit_logic_pred(ctx, ALU_OP2_PRED_SETNE_INT);
>> + int alu_type = CF_OP_ALU_PUSH_BEFORE;
>> +
>> + /*
>> + There is a bug where a BREAK/CONTINUE followed by LOOP_STARTxxx
>> for nested
>> + loops may put the branch stack into a state such that
>> ALU_PUSH_BEFORE
>> + doesn't work as expected. Workaround this by replacing the
>> ALU_PUSH_BEFORE
>> + with a PUSH + ALU for nested loops.
>> + */
>> + if (ctx->bc->chip_class == CAYMAN &&
>> need_cayman_loop_bug_workaround(ctx)) {
>
>
> We already have current loop level for the stack size computation, see
> r600_bytecode::stack, so I think need_cayman_loop_bug_workaround call may be
> replaced with "ctx->bc->stack.loop > 1", if I'm not missing something.
Ok, will try that tonight. Should I add a comment that it is a hardware bug?
> Vadim
>
>
>> + r600_bytecode_add_cfinst(ctx->bc, CF_OP_PUSH);
>> + alu_type = CF_OP_ALU;
>> + }
>> +
>> + emit_logic_pred(ctx, ALU_OP2_PRED_SETNE_INT, alu_type);
>>
>> r600_bytecode_add_cfinst(ctx->bc, CF_OP_JUMP);
>>
>> @@ -5834,6 +5848,19 @@ static int tgsi_loop_brk_cont(struct
>> r600_shader_ctx *ctx)
>> return 0;
>> }
>>
>> +static bool need_cayman_loop_bug_workaround(struct r600_shader_ctx *ctx)
>> +{
>> + unsigned int fscp;
>> + int num_loops = 0;
>> + for (fscp = ctx->bc->fc_sp; fscp > 0; fscp--)
>> + {
>> + if (FC_LOOP == ctx->bc->fc_stack[fscp].type)
>> + ++num_loops;
>> + }
>> +
>> + return num_loops >= 2;
>> +}
>> +
>> static int tgsi_umad(struct r600_shader_ctx *ctx)
>> {
>> struct tgsi_full_instruction *inst =
>> &ctx->parse.FullToken.FullInstruction;
>>
>
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