i965/fs: Actually set/use the mlen for gen7 uniform pull constant loads

Previously, we were allocating the payload with different sizes per gen and
then figuring out the mlen in the generator based on gen.  This meant,
among other things, that the higher level passes knew nothing about it.

Acked-by: Francisco Jerez <currojerez@riseup.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
diff --git a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
index 2ed0bac..8d821ab 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
@@ -1054,7 +1054,6 @@
                                                        struct brw_reg index,
                                                        struct brw_reg offset)
 {
-   assert(inst->mlen == 0);
    assert(index.type == BRW_REGISTER_TYPE_UD);
 
    assert(offset.file == BRW_GENERAL_REGISTER_FILE);
@@ -1069,12 +1068,10 @@
 
    struct brw_reg src = offset;
    bool header_present = false;
-   int mlen = 1;
 
    if (devinfo->gen >= 9) {
       /* Skylake requires a message header in order to use SIMD4x2 mode. */
-      src = retype(brw_vec4_grf(offset.nr - 1, 0), BRW_REGISTER_TYPE_UD);
-      mlen = 2;
+      src = retype(brw_vec4_grf(offset.nr, 0), BRW_REGISTER_TYPE_UD);
       header_present = true;
 
       brw_push_insn_state(p);
@@ -1105,7 +1102,7 @@
                               0, /* LD message ignores sampler unit */
                               GEN5_SAMPLER_MESSAGE_SAMPLE_LD,
                               1, /* rlen */
-                              mlen,
+                              inst->mlen,
                               header_present,
                               BRW_SAMPLER_SIMD_MODE_SIMD4X2,
                               0);
@@ -1135,7 +1132,7 @@
                               0, /* LD message ignores sampler unit */
                               GEN5_SAMPLER_MESSAGE_SAMPLE_LD,
                               1, /* rlen */
-                              mlen,
+                              inst->mlen,
                               header_present,
                               BRW_SAMPLER_SIMD_MODE_SIMD4X2,
                               0);