Nicolai writes:
When the pixmap pixel format has no alpha channel, the x11 driver
(software rendering) adds a wrapped alpha channel on request.
During SwapBuffers, this alpha channel is not copied from back to
front, which means that the front buffer doesn't really contain the
contents that the back buffer previously contained.
A subsequent glReadPixels from the front buffer will return an
incorrect result. The following patch attempts to fix this.
IR_LOOP now has two children: the body code, and the tail code.
Tail code is the "i++" part of a for-loop, or the expression at the end
of a "do {} while(expr);" loop.
"continue" translates into: "execute tail code; CONT;"
Also, the test for infinite do/while loops was incorrect.
ctx->Shader.EmitCondCodes determines if we use condition codes.
If not, IF statement uses first operand's X component as the condition.
Added OPCODE_BRK0, OPCODE_BRK1, OPCODE_CONT0, OPCODE_CONT1 to handle
the common cases of conditional break/continue.
Previously, comparing vec2, vec3, vec4 was broken.
Added IR_EQUAL, IR_NOTEQUAL nodes/operators to compute boolean
equality/inequality vs. IR_SEQUAL/IR_SNEQUAL which work component-wise.
Use IR_EQUAL/IR_NOTEQUAL for the == and != operators.
To compute vec4 equality, use SNE, DP4, SEQ instruction sequence.
There are times when we don't want to allow swizzling when searching for or
adding vector constants. Passing NULL for swizzleOut disables swizzling.
This fixes a constant/swizzle bug in link_uniform_vars().
The index is no longer necessary to share constants between multiple
SIN/COS/SCS instructions inside a single fragment program, and storing
a tiny implementation detail like this in the fragment_program structure
itself was just nasty.
The constant/parameter allocation was significantly simplified, removing
one unnecessary copy operation of parameters. The dirty state tracking is
unchanged and far from optimal, since all state is always re-fetched.
Constants and parameters are now emitted only once, which significantly
reduces the resource pressure on larger programs.
