This stuffs them all in a struct for sanity. Fixes piglit
glsl-1.30/execution/switch/fs-uniform-nested.
NOTE: This is a candidate for the 8.0 branch.
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Up until now modifying the GLSL compiler has been pretty straightforward.
This is where things get interesting. But still pretty straightforward.
Switch statements can be thought of a series of if/then/else statements.
Case labels are compared with the value of a test expression and the case
statements are executed if the comparison is true.
There are a couple of aspects of switch statements that complicate this simple
view of the world. The primary one is that cases can fall through sequentially
to subsequent case, unless a break statement is encountered, in which case,
the switch statement exits completely.
But break handling is further complicated by the fact that a break statement
can impact the exit of a loop. Thus, we need to coordinate break processing
between switch statements and loop statements.
The code generated by a switch statement maintains three temporary state
variables:
int test_value;
bool is_fallthru;
bool is_break;
test_value is initialized to the value of the test expression at the head of
the switch statement. This is the value that case labels are compared against.
is_fallthru is used to sequentially fall through to subsequent cases and is
initialized to false. When a case label matches the test expression, this
state variable is set to true. It will also be forced to false if a break
statement has been encountered. This forcing to false on break MUST be
after every case test. In practice, we defer that forcing to immediately after
the last case comparison prior to executing a case statement, but that is
an optimization.
is_break is used to indicate that a break statement has been executed and is
initialized to false. When a break statement is encountered, it is set to true.
This state variable is then used to conditionally force is_fallthru to to false
to prevent subsequent case statements from executing.
Code generation for break statements depends on whether the break statement is
inside a switch statement or inside a loop statement. If it inside a loop
statement is inside a break statement, the same code as before gets generated.
But if a switch statement is inside a loop statement, code is emitted to set
the is_break state to true.
Just as ASTs for loop statements are managed in a stack-like
manner to handle nesting, we also add a bool to capture the innermost switch
or loop condition. Note that we still need to maintain a loop AST stack to
properly handle for-loop code generation on a continue statement. Technically,
we don't (yet) need a switch AST stack, but I am using one for orthogonality
with loop statements, in anticipation of future use. Note that a simple
boolean stack would have sufficed.
We will illustrate a switch statement with its analogous conditional code that
a switch statement corresponds to by examining an example.
Consider the following switch statement:
switch (42) {
case 0:
case 1:
gl_FragColor = vec4(1.0, 2.0, 3.0, 4.0);
case 2:
case 3:
gl_FragColor = vec4(4.0, 3.0, 2.0, 1.0);
break;
case 4:
default:
gl_FragColor = vec4(0.0, 0.0, 0.0, 0.0);
}
Note that case 0 and case 1 fall through to cases 2 and 3 if they occur.
Note that case 4 and the default case must be reached explicitly, since cases
2 and 3 break at the end of their case.
Finally, note that case 4 and the default case don't break but simply fall
through to the end of the switch.
For this code, the equivalent code can be expressed as:
int test_val = 42; // capture value of test expression
bool is_fallthru = false; // prevent initial fall through
bool is_break = false; // capture the execution of a break stmt
is_fallthru |= (test_val == 0); // enable fallthru on case 0
is_fallthru |= (test_val == 1); // enable fallthru on case 1
is_fallthru &= !is_break; // inhibit fallthru on previous break
if (is_fallthru) {
gl_FragColor = vec4(1.0, 2.0, 3.0, 4.0);
}
is_fallthru |= (test_val == 2); // enable fallthru on case 2
is_fallthru |= (test_val == 3); // enable fallthru on case 3
is_fallthru &= !is_break; // inhibit fallthru on previous break
if (is_fallthru) {
gl_FragColor = vec4(4.0, 3.0, 2.0, 1.0);
is_break = true; // inhibit all subsequent fallthru for break
}
is_fallthru |= (test_val == 4); // enable fallthru on case 4
is_fallthru = true; // enable fallthru for default case
is_fallthru &= !is_break; // inhibit fallthru on previous break
if (is_fallthru) {
gl_FragColor = vec4(0.0, 0.0, 0.0, 0.0);
}
The code generate for |= and &= uses the conditional assignment capabilities
of the IR.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This extension introduces a new sampler type: samplerExternalOES.
texture2D (and texture2DProj) can be used to do a texture look up in an
external texture.
Reviewed-by: Brian Paul <brianp@vmware.com>
Acked-by: Jakob Bornecrantz <jakob@vmware.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
It's the same as GL_AMD_conservative_depth. The specs have slight
differences in wording, but don't differ in content or behavior.
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
The ast-to-hir conversion needs to emit function signatures in two
circumstances: when a function declaration (or definition) is
encountered, and when a built-in function is encountered.
To avoid emitting a function signature in an illegal place (such as
inside a function), emit_function() checked whether we were inside a
function definition, and if so, emitted the signature before the
function definition.
However, this didn't cover the case of emitting function signatures
for built-in functions when those built-in functions are called from
inside the constant integer expression that specifies the length of a
global array. This failed because when processing an array length, we
are emitting IR into a dummy exec_list (see process_array_type() in
ast_to_hir.cpp). process_array_type() later checks (via an assertion)
that no instructions were emitted to the dummy exec_list, based on the
reasonable assumption that we shouldn't need to emit instructions to
calculate the value of a constant.
This patch changes emit_function() so that it emits function
signatures at toplevel in all cases.
This partially fixes bug 38625
(https://bugs.freedesktop.org/show_bug.cgi?id=38625). The remainder
of the fix is in the patch that follows.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
These were previously 1-bit-wide bitfields. Changing them to bools
has a negligible performance impact, and allows them to be accessed by
offset as well as by direct structure access.
NOTE: This is a candidate for the 7.10 and 7.11 branches.
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
It's just an alias of the ARB variant with some GLSL compiler changes.
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Previously we'd happily compile GLSL 1.30 shaders on any driver. We'd
also happily compile GLSL 1.10 and 1.20 shaders in an ES2 context.
This has been a long standing FINISHME in the compiler.
NOTE: This is a candidate for the 7.9 and 7.10 branches
When AMD_conservative_depth is enabled:
* Let 'layout' be a token.
* Extend the production rule of layout_qualifier_id to process the tokens:
depth_any
depth_greater
depth_less
depth_unchanged
Previously the 'STDGL invariant(all)' pragma added in GLSL 1.20 was
simply ignored by the compiler. This adds support for setting all
variable invariant.
In GLSL 1.10 and GLSL ES 1.00 the pragma is ignored, per the specs,
but a warning is generated.
Fixes piglit test glsl-invariant-pragma and bugzilla #31925.
NOTE: This is a candidate for the 7.9 and 7.10 branches.
This adds proper support for the GL_ARB_shader_stencil_export extension
to the GLSL compiler. Thanks to Ian for pointing out where I need to add things.
This is an invasive set of changes. Each user shader tracks a set of other
shaders that contain built-in functions. During compilation, function
prototypes are imported from these shaders. During linking, the
shaders are linked with these built-in-function shaders just like with
any other shader.
In both the preprocessor and in the compiler proper, we use a custom
yyltype struct to allow tracking the source-string number in addition
to line and column. However, we were previously relying on bison's
default initialization of the yyltype struct which of course is not
aware of the source field and leaves it uninitialized.
We fix this by defining our own YYLLOC_DEFAULT macro expanding on the
default version (as appears in the bison manual) and adding
initialization of yylloc.source.
Most places in the code simply use a static name, which works because
names are never used to look up an ir_variable. generate_temporary is
simply unnecessary (and looks like it would leak memory, and isn't
thread safe...)
This doesn't do any control flow analysis to ensure that the return
statements are actually reached.
Fixes piglit tests function5.frag and function-07.vert.
