When an instruction has a side effect, it impacts the available options when
reordering an instruction. As the EOT flag is an implied write to the render
target in the FS, it can be considered a side effect.
This patch shouldn't actually have any impact on the current code since the EOT
flag implies that the opcode is already one with side effects,
FS_OPCODE_FB_WRITE. The next patch however will introduce an optimization
whereby the EOT flag can occur with an opcode SHADER_OPCODE_TEX, and as that
instruction will perform the same implied write to the render target, it cannot
be reordered.
Cc: Matt Turner <matts...@gmail.com>
Cc: Kenneth Graunke <kenn...@whitecape.org>
Signed-off-by: Ben Widawsky <b...@bwidawsk.net>
---
src/mesa/drivers/dri/i965/brw_fs.cpp | 7 +++++++
src/mesa/drivers/dri/i965/brw_ir_fs.h | 1 +
2 files changed, 8 insertions(+)
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp
b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 9c2ccce..e540dd1 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -531,6 +531,13 @@ fs_inst::can_do_source_mods(struct brw_context *brw)
return true;
}
+
+bool
+fs_inst::has_side_effects() const
+{
+ return this->eot || backend_instruction::has_side_effects();
+}
+
void
fs_reg::init()
{
diff --git a/src/mesa/drivers/dri/i965/brw_ir_fs.h
b/src/mesa/drivers/dri/i965/brw_ir_fs.h
index 9ef1261..30c19f4 100644
--- a/src/mesa/drivers/dri/i965/brw_ir_fs.h
+++ b/src/mesa/drivers/dri/i965/brw_ir_fs.h
@@ -225,6 +225,7 @@ public:
bool is_partial_write() const;
int regs_read(int arg) const;
bool can_do_source_mods(struct brw_context *brw);
+ bool has_side_effects() const;
bool reads_flag() const;
bool writes_flag() const;
--
2.3.5
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