nvc0/ir: try to use the optimal texture op mode

Don't really know what they are yet but for groups of textures, the
last one should use mode "p" and the others "t".

src/gallium/drivers/nvc0/codegen/nv50_ir_emit_nvc0.cpp

@@ -965,13 +965,25 @@ void CodeEmitterNVC0::emitTEXCSAA(const TexInstruction *i)
    srcId(i->src(0), 20);
 }
 
+static inline bool
+isNextIndependentTex(const TexInstruction *i)
+{
+   if (!i->next || !isTextureOp(i->next->op))
+      return false;
+   if (i->getDef(0)->interfers(i->next->getSrc(0)))
+      return false;
+   return !i->next->srcExists(1) || !i->getDef(0)->interfers(i->next->getSrc(1));
+}
+
 void
 CodeEmitterNVC0::emitTEX(const TexInstruction *i)
 {
    code[0] = 0x00000006;
 
-   if (1)
-      code[0] |= 0x80; // normal/t/p mode = t, XXX: what is this ?
+   if (isNextIndependentTex(i))
+      code[0] |= 0x080; // t mode
+   else
+      code[0] |= 0x100; // p mode
 
    if (i->tex.liveOnly)
       code[0] |= 1 << 9;
@@ -1021,7 +1033,7 @@ CodeEmitterNVC0::emitTEX(const TexInstruction *i)
    if (i->tex.target.isShadow())
       code[1] |= 1 << 24;
 
-   const int src1 = MAX2(i->predSrc + 1, 1); // if predSrc == 1, no 2nd src
+   const int src1 = (i->predSrc == 1) ? 2 : 1; // if predSrc == 1, !srcExists(2)
 
    if (i->srcExists(src1) && i->src(src1).getFile() == FILE_IMMEDIATE) {
       // lzero