From: Iago Toral Quiroga <ito...@igalia.com>
We were not accounting for reg_suboffset in the check for the start
of the region. This meant that would allow copy-propagation even if
the dst wrote to sub_regoffset 4 and our source read from
sub_regoffset 0, which is not correct. This was observed in fp64 code,
since there we use reg_suboffset to select the high 32-bit of a double.
Also, fs_reg::regs_read() already takes the stride into account, so we
should not multiply its result by the stride again. This was making
copy-propagation fail to copy-propagate cases that would otherwise be
safe to copy-propagate. Again, this was observed in fp64 code, since
there we use stride > 1 often.
Incidentally, these fixes open up more possibilities for copy propagation
which uncovered new bugs in copy-propagation. The folowing patches address
each of these new issues.
---
.../drivers/dri/i965/brw_fs_copy_propagation.cpp | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
index 5fae10f..23df877 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
@@ -329,6 +329,15 @@ can_take_stride(fs_inst *inst, unsigned arg, unsigned
stride,
return true;
}
+static inline bool
+region_match(fs_reg src, unsigned regs_read,
+ fs_reg dst, unsigned regs_written)
+{
+ return src.reg_offset >= dst.reg_offset &&
+ (src.reg_offset + regs_read) <= (dst.reg_offset + regs_written) &&
+ src.subreg_offset >= dst.subreg_offset;
+}
+
bool
fs_visitor::try_copy_propagate(fs_inst *inst, int arg, acp_entry *entry)
{
@@ -351,10 +360,8 @@ fs_visitor::try_copy_propagate(fs_inst *inst, int arg,
acp_entry *entry)
/* Bail if inst is reading a range that isn't contained in the range
* that entry is writing.
*/
- if (inst->src[arg].reg_offset < entry->dst.reg_offset ||
- (inst->src[arg].reg_offset * 32 + inst->src[arg].subreg_offset +
- inst->regs_read(arg) * inst->src[arg].stride * 32) >
- (entry->dst.reg_offset + entry->regs_written) * 32)
+ if (!region_match(inst->src[arg], inst->regs_read(arg),
+ entry->dst, entry->regs_written))
return false;
/* we can't generally copy-propagate UD negations because we
@@ -554,10 +561,8 @@ fs_visitor::try_constant_propagate(fs_inst *inst,
acp_entry *entry)
/* Bail if inst is reading a range that isn't contained in the range
* that entry is writing.
*/
- if (inst->src[i].reg_offset < entry->dst.reg_offset ||
- (inst->src[i].reg_offset * 32 + inst->src[i].subreg_offset +
- inst->regs_read(i) * inst->src[i].stride * 32) >
- (entry->dst.reg_offset + entry->regs_written) * 32)
+ if (!region_match(inst->src[i], inst->regs_read(i),
+ entry->dst, entry->regs_written))
continue;
fs_reg val = entry->src;
--
2.5.0
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