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Changes in v2:
- Base class renamed to ir_control_flow_visitor
- Tried to comply with coding style
This is a new pass that supersedes ir_if_return and "lowers" jumps
to if/else structures.
Currently it causes no regressions on softpipe and nv40, but I'm not sure
whether the piglit glsl tests are thorough enough, so consider this
experimental.
It can be asked to:
1. Pull jumps out of ifs where possible
2. Remove all "continue"s, replacing them with an "execute flag"
3. Replace all "break" with a single conditional one at the end of the loop
4. Replace all "return"s with a single return at the end of the function,
for the main function and/or other functions
This gives several great benefits:
1. All functions can be inlined after this pass
2. nv40 and other pre-DX10 chips without "continue" can be supported
3. nv30 and other pre-DX10 chips with no control flow at all are better supported
Note that for full effect we should also teach the unroller to unroll
loops with a fixed maximum number of iterations but with the canonical
conditional "break" that this pass will insert if asked to.
Continues are lowered by adding a per-loop "execute flag", initialized to
TRUE, that when cleared inhibits all execution until the end of the loop.
Breaks are lowered to continues, plus setting a "break flag" that is checked
at the end of the loop, and trigger the unique "break".
Returns are lowered to breaks/continues, plus adding a "return flag" that
causes loops to break again out of their enclosing loops until all the
loops are exited: then the "execute flag" logic will ignore everything
until the end of the function.
Note that "continue" and "return" can also be implemented by adding
a dummy loop and using break.
However, this is bad for hardware with limited nesting depth, and
prevents further optimization, and thus is not currently performed.
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The problem with doing it on the way in is that for a function with
multiple early returns, we'll move an outer block in, then restart the
pass, then move the two inside returns out, then never move outer
blocks in again because the remaining early returns are inside an else
block and they don't know that there's a return just after their
block. By going inside-out, we get the early returns stacked up so
that they all move out with a series of
move_returns_after_block().
Fixes (on i965):
glsl-fs-raytrace-bug27060
glsl-vs-raytrace-bug26691
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This catches a few remaining functions that weren't getting inlined,
generally operating on global or out variables and using an early
return to skip work when possible.
Fixes for i965:
glsl1-function with early return (3)
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This makes many remaining functions inlinable.
Fixes for i965:
glsl1-function with early return (1)
glsl1-function with early return (2)
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This is quite a large patch because breaking it into smaller pieces
would result in the tree being intermitently broken. The big changes
are:
* Add the ir_var_temporary variable mode
* Change the ir_variable constructor to take the mode as a
parameter and correctly specify the mode for all ir_varables.
* Change the linker to not cross validate ir_var_temporary
variables.
* Change the linker to pull all ir_var_temporary variables from
global scope into 'main'.
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This allows function inlining making the following tests work even
without function calls implemented:
glsl-fs-functions-2
glsl-fs-functions-3
glsl-vs-functions
glsl-vs-functions-2
glsl-vs-functions-3
glsl-vs-vec4-indexing-5
(Note that those tests were designed to trigger actual function calls,
and this defeats them. However, those testcases ended up catching the
bug in the previous commit.)
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