i965/fs: Fix texelFetchOffset() on pre-Gen7.

Commit f41ecade7b458c02d504158b522acb2231585040 fixed texelFetchOffset()
on Ivybridge, but didn't update the Ironlake/Sandybridge code.

+15 piglits on Sandybridge.

NOTE: This and f41ecade7b458 are both candidates for stable branches.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>

diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index 275a1f4ef83930603cd8da724f068be72ebf5512..845ab49972c1b29f3d344b028ca88eec44f1ba7a 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -884,20 +884,36 @@ fs_visitor::emit_texture_gen5(ir_texture *ir, fs_reg dst, fs_reg coordinate,
    const int vector_elements =
       ir->coordinate ? ir->coordinate->type->vector_elements : 0;
 
-   if (ir->offset) {
-      /* The offsets set up by the ir_texture visitor are in the
-       * m1 header, so we can't go headerless.
+   if (ir->offset != NULL && ir->op == ir_txf) {
+      /* It appears that the ld instruction used for txf does its
+       * address bounds check before adding in the offset.  To work
+       * around this, just add the integer offset to the integer texel
+       * coordinate, and don't put the offset in the header.
        */
-      header_present = true;
-      mlen++;
-      base_mrf--;
-   }
+      ir_constant *offset = ir->offset->as_constant();
+      for (int i = 0; i < vector_elements; i++) {
+        emit(BRW_OPCODE_ADD,
+             fs_reg(MRF, base_mrf + mlen + i * reg_width, coordinate.type),
+             coordinate,
+             offset->value.i[i]);
+        coordinate.reg_offset++;
+      }
+   } else {
+      if (ir->offset) {
+        /* The offsets set up by the ir_texture visitor are in the
+         * m1 header, so we can't go headerless.
+         */
+        header_present = true;
+        mlen++;
+        base_mrf--;
+      }
 
-   for (int i = 0; i < vector_elements; i++) {
-      emit(BRW_OPCODE_MOV,
-          fs_reg(MRF, base_mrf + mlen + i * reg_width, coordinate.type),
-          coordinate);
-      coordinate.reg_offset++;
+      for (int i = 0; i < vector_elements; i++) {
+        emit(BRW_OPCODE_MOV,
+             fs_reg(MRF, base_mrf + mlen + i * reg_width, coordinate.type),
+             coordinate);
+        coordinate.reg_offset++;
+      }
    }
    mlen += vector_elements * reg_width;