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i965/eu: Refactor jump distance scaling to use a helper function.

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Different generations of hardware measure jump distances in different
units.  Previously, every function that needed to set a jump target open
coded this scaling, or made a hardcoded assumption (i.e. just used 2).

Most functions start with the number of instructions to jump, and scale
up to the hardware-specific value.  So, I made the function match that.

Others start with a byte offset, and divide by a constant (8) to obtain
the jump distance.  This is actually 16 / 2 (the jump scale for Gen5-7).

v2: Make the helper a static inline defined in brw_eu.h, instead of
    an actual function in brw_eu_emit.c (as suggested by Matt).

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Matt Turner <mattst88@gmail.com>
This commit is contained in:
Kenneth Graunke 2014-06-30 08:00:25 -07:00
parent a1c899c718
commit 82ddd517af
3 changed files with 32 additions and 17 deletions
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20
src/mesa/drivers/dri/i965/brw_eu.h
View file

@ -316,6 +316,26 @@ void brw_shader_time_add(struct brw_compile *p,
struct brw_reg payload,
uint32_t surf_index);
/**
* Return the generation-specific jump distance scaling factor.
*
* Given the number of instructions to jump, we need to scale by
* some number to obtain the actual jump distance to program in an
* instruction.
*/
static inline unsigned
brw_jump_scale(const struct brw_context *brw)
{
/* Ironlake and later measure jump targets in 64-bit data chunks (in order
* (to support compaction), so each 128-bit instruction requires 2 chunks.
*/
if (brw->gen >= 5)
return 2;
/* Gen4 simply uses the number of 128-bit instructions. */
return 1;
}
/* If/else/endif. Works by manipulating the execution flags on each
* channel.
*/

21
src/mesa/drivers/dri/i965/brw_eu_emit.c
View file

@ -1333,12 +1333,7 @@ patch_IF_ELSE(struct brw_compile *p,
assert(endif_inst != NULL);
assert(else_inst == NULL || brw_inst_opcode(brw, else_inst) == BRW_OPCODE_ELSE);
unsigned br = 1;
/* Jump count is for 64bit data chunk each, so one 128bit instruction
* requires 2 chunks.
*/
if (brw->gen >= 5)
br = 2;
unsigned br = brw_jump_scale(brw);
assert(brw_inst_opcode(brw, endif_inst) == BRW_OPCODE_ENDIF);
brw_inst_set_exec_size(brw, endif_inst, brw_inst_exec_size(brw, if_inst));
@ -1635,7 +1630,7 @@ brw_patch_break_cont(struct brw_compile *p, brw_inst *while_inst)
struct brw_context *brw = p->brw;
brw_inst *do_inst = get_inner_do_insn(p);
brw_inst *inst;
int br = (brw->gen == 5) ? 2 : 1;
unsigned br = brw_jump_scale(brw);
assert(brw->gen < 6);
@ -1659,10 +1654,7 @@ brw_WHILE(struct brw_compile *p)
{
struct brw_context *brw = p->brw;
brw_inst *insn, *do_insn;
unsigned br = 1;
if (brw->gen >= 5)
br = 2;
unsigned br = brw_jump_scale(brw);
if (brw->gen >= 7) {
insn = next_insn(p, BRW_OPCODE_WHILE);
@ -2346,7 +2338,7 @@ brw_find_loop_end(struct brw_compile *p, int start_offset)
{
struct brw_context *brw = p->brw;
int offset;
int scale = 8;
int scale = 16 / brw_jump_scale(brw);
void *store = p->store;
assert(brw->gen >= 6);
@ -2378,7 +2370,8 @@ brw_set_uip_jip(struct brw_compile *p)
{
struct brw_context *brw = p->brw;
int offset;
int scale = 8;
int br = brw_jump_scale(brw);
int scale = 16 / br;
void *store = p->store;
if (brw->gen < 6)
@ -2418,7 +2411,7 @@ brw_set_uip_jip(struct brw_compile *p)
case BRW_OPCODE_ENDIF:
if (block_end_offset == 0)
brw_inst_set_jip(brw, insn, 2);
brw_inst_set_jip(brw, insn, 1 * br);
else
brw_inst_set_jip(brw, insn, (block_end_offset - offset) / scale);
break;

8
src/mesa/drivers/dri/i965/brw_fs_generator.cpp
View file

@ -67,6 +67,8 @@ fs_generator::patch_discard_jumps_to_fb_writes()
if (brw->gen < 6 || this->discard_halt_patches.is_empty())
return false;
int scale = brw_jump_scale(brw);
/* There is a somewhat strange undocumented requirement of using
* HALT, according to the simulator. If some channel has HALTed to
* a particular UIP, then by the end of the program, every channel
@ -79,8 +81,8 @@ fs_generator::patch_discard_jumps_to_fb_writes()
* tests.
*/
brw_inst *last_halt = gen6_HALT(p);
brw_inst_set_uip(brw, last_halt, 2);
brw_inst_set_jip(brw, last_halt, 2);
brw_inst_set_uip(brw, last_halt, 1 * scale);
brw_inst_set_jip(brw, last_halt, 1 * scale);
int ip = p->nr_insn;
@ -89,7 +91,7 @@ fs_generator::patch_discard_jumps_to_fb_writes()
assert(brw_inst_opcode(brw, patch) == BRW_OPCODE_HALT);
/* HALT takes a half-instruction distance from the pre-incremented IP. */
brw_inst_set_uip(brw, patch, (ip - patch_ip->ip) * 2);
brw_inst_set_uip(brw, patch, (ip - patch_ip->ip) * scale);
}
this->discard_halt_patches.make_empty();