So the nv40 code is doing the wrong thing... :)
The rule currently is that the generic tags are just tags and are used only to
establish mapping between fragment shader and vertex shader. Additionaly the
vertex shader should always supply at least the inputs required by the fragment
shader. Taking a guess, without specific hardware support for routing, nv40
should translate the fragment shader inputs into successive SRC_TC slots, and
build a mapping from semantic-index -> SRC_TC slot that can be applied when
translating the vertex shader.
You might complain that in this world a vertex shader will require multiple
translations depending on which fragment shader is bound, as one taking fewer
inputs will have different numberings. That's true, but you also get the
opportunity to specialize the vertex shader as a result, eliminating dead code
in each case - which may be worth the effort.
Anyway, it sounds like what you really want is to change the linkage rules.
This is possible, of course, but we should discuss it in those terms. And then
if we do revisit those rules, we should take a deeper look at linkage and
figure out if anything else can be changed.
Keith
________________________________________
From: luca.barbi...@gmail.com [luca.barbi...@gmail.com] On Behalf Of Luca
Barbieri [l...@luca-barbieri.com]
Sent: Friday, January 29, 2010 10:15 AM
To: Brian Paul
Cc: Keith Whitwell; mesa3d-dev@lists.sourceforge.net
Subject: Re: [Mesa3d-dev] [PATCH] glsl: put varyings in texcoord slots
As a concrete example, the current nv40 code does this during fragment
program translation.
case TGSI_SEMANTIC_GENERIC:
if (fdec->Semantic.Index <= 7) {
hw = NV40_FP_OP_INPUT_SRC_TC(fdec->Semantic.
Index);
} else {
NOUVEAU_ERR("bad generic semantic index\n");
return FALSE;
}
break;
As a result, GLSL completely fails to work on nv30 and nv40.
nv50 instead seems to have hardware routing support, which is used by
the driver.
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