On 18/09/17 20:09, Nicolai Hähnle wrote:
On 14.09.2017 06:47, Timothy Arceri wrote:
These instruction will be executed on every iteration of the loop
we cannot drop them.
---
src/compiler/glsl/loop_analysis.h | 7 +++++++
src/compiler/glsl/loop_controls.cpp | 15 +++++++++++++++
src/compiler/glsl/loop_unroll.cpp | 7 -------
3 files changed, 22 insertions(+), 7 deletions(-)
diff --git a/src/compiler/glsl/loop_analysis.h
b/src/compiler/glsl/loop_analysis.h
index 2894c6359b..0e1bfd8142 100644
--- a/src/compiler/glsl/loop_analysis.h
+++ b/src/compiler/glsl/loop_analysis.h
@@ -27,20 +27,27 @@
#include "ir.h"
#include "util/hash_table.h"
/**
* Analyze and classify all variables used in all loops in the
instruction list
*/
extern class loop_state *
analyze_loop_variables(exec_list *instructions);
+static inline bool
+is_break(ir_instruction *ir)
+{
+ return ir != NULL && ir->ir_type == ir_type_loop_jump &&
+ ((ir_loop_jump *) ir)->is_break();
+}
+
/**
* Fill in loop control fields
*
* Based on analysis of loop variables, this function tries to remove
* redundant sequences in the loop of the form
*
* (if (expression bool ...) (break))
*
* For example, if it is provable that one loop exit condition will
diff --git a/src/compiler/glsl/loop_controls.cpp
b/src/compiler/glsl/loop_controls.cpp
index 895954fc2d..2dff26aec0 100644
--- a/src/compiler/glsl/loop_controls.cpp
+++ b/src/compiler/glsl/loop_controls.cpp
@@ -215,21 +215,36 @@ loop_control_visitor::visit_leave(ir_loop *ir)
* that are associated with a fixed iteration count, except for
the one
* associated with the limiting terminator--that one needs to
stay, since
* it terminates the loop. Exception: if the loop still has a
normative
* bound, then that terminates the loop, so we don't even need
the limiting
* terminator.
*/
foreach_in_list(loop_terminator, t, &ls->terminators) {
if (t->iterations < 0)
continue;
+ exec_list *branch_instructions;
if (t != ls->limiting_terminator) {
+ ir_instruction *ir_if_last = (ir_instruction *)
+ t->ir->then_instructions.get_tail();
+ if (is_break(ir_if_last)) {
+ branch_instructions = &t->ir->else_instructions;
+ } else {
+ branch_instructions = &t->ir->then_instructions;
+ assert(is_break(ir_if_last));
This should probably be
assert(is_break((ir_instruction
*)t->ir->else_instructions.get_tail()));
Yeah that looks right.
The fact that this wasn't hit suggests that maybe we need a piglit test
for this?
I'll double check but I recall the break always being put in the then
branch regardless of what the GLSL looks like. This is here for
completeness more than anything.
(I generally suggest running CTS / piglit with an optimized build that
has assertions enabled. My configure line for that looks like this
Yes, I always test this way :) although occasionally I do forget to rebuild.
../mesa-src/configure --prefix=$PREFIX_SAN --enable-sanitize=address
--with-dri-drivers=no --with-gallium-drivers=swrast,r300,r600,radeonsi
--with-egl-platforms=x11,drm --enable-texture-float
--enable-llvm-shared-libs --enable-glx-tls --enable-debug
--with-vulkan-drivers=radeon CC=/usr/lib/ccache/cc
CXX=/usr/lib/ccache/c++ "CFLAGS=-fno-omit-frame-pointer -g -O2"
"CXXFLAGS=-fno-omit-frame-pointer -g -O2"
Now that I look at it, parts are probably outdated, but the basic idea
of --enable-debug and -g -O2 is sound :) )
Cheers,
Nicolai
+ }
+
+ exec_list copy_list;
+ copy_list.make_empty();
+ clone_ir_list(ir, ©_list, branch_instructions);
+
+ t->ir->insert_before(©_list);
t->ir->remove();
assert(ls->num_loop_jumps > 0);
ls->num_loop_jumps--;
this->progress = true;
}
}
return visit_continue;
diff --git a/src/compiler/glsl/loop_unroll.cpp
b/src/compiler/glsl/loop_unroll.cpp
index dbb3fa2fa5..7f601295a1 100644
--- a/src/compiler/glsl/loop_unroll.cpp
+++ b/src/compiler/glsl/loop_unroll.cpp
@@ -46,27 +46,20 @@ public:
void splice_post_if_instructions(ir_if *ir_if, exec_list
*splice_dest);
loop_state *state;
bool progress;
const struct gl_shader_compiler_options *options;
};
} /* anonymous namespace */
-static bool
-is_break(ir_instruction *ir)
-{
- return ir != NULL && ir->ir_type == ir_type_loop_jump
- && ((ir_loop_jump *) ir)->is_break();
-}
-
class loop_unroll_count : public ir_hierarchical_visitor {
public:
int nodes;
bool unsupported_variable_indexing;
bool array_indexed_by_induction_var_with_exact_iterations;
/* If there are nested loops, the node count will be inaccurate. */
bool nested_loop;
loop_unroll_count(exec_list *list, loop_variable_state *ls,
const struct gl_shader_compiler_options *options)
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