diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
index 7bdfc4edcab..403e2cc8031 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -1140,7 +1140,7 @@ vec4_visitor::opt_register_coalesce()
       /* Can't coalesce this GRF if someone else was going to
        * read it later.
        */
-      if (var_range_end(var_from_reg(alloc, dst_reg(inst->src[0])), 4) > ip)
+      if (var_range_end(var_from_reg(alloc, dst_reg(inst->src[0])), 8) > ip)
 	 continue;
 
       /* We need to check interference with the final destination between this
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp b/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
index bf7e4a4f070..eed2478cda9 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
@@ -248,7 +248,7 @@ vec4_visitor::opt_cse_local(bblock_t *block)
              * more -- a sure sign they'll fail operands_match().
              */
             if (src->file == VGRF) {
-               if (var_range_end(var_from_reg(alloc, dst_reg(*src)), 4) < ip) {
+               if (var_range_end(var_from_reg(alloc, dst_reg(*src)), 8) < ip) {
                   entry->remove();
                   ralloc_free(entry);
                   break;
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp b/src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp
index 9185d5202b9..5b22a096dd1 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp
@@ -57,13 +57,12 @@ vec4_visitor::dead_code_eliminate()
          if ((inst->dst.file == VGRF && !inst->has_side_effects()) ||
              (inst->dst.is_null() && inst->writes_flag())){
             bool result_live[4] = { false };
-
             if (inst->dst.file == VGRF) {
-               for (unsigned i = 0; i < regs_written(inst); i++) {
-                  for (int c = 0; c < 4; c++)
-                     result_live[c] |= BITSET_TEST(live,
-                        var_from_reg(alloc,
-                                     byte_offset(inst->dst, i * REG_SIZE), c));
+               for (unsigned i = 0; i < DIV_ROUND_UP(inst->size_written, 16); i++) {
+                  for (int c = 0; c < 4; c++) {
+                     const unsigned v = var_from_reg(alloc, inst->dst, c, i);
+                     result_live[c] |= BITSET_TEST(live, v);
+                  }
                }
             } else {
                for (unsigned c = 0; c < 4; c++)
@@ -112,14 +111,11 @@ vec4_visitor::dead_code_eliminate()
 
          if (inst->dst.file == VGRF && !inst->predicate &&
              !inst->is_align1_partial_write()) {
-            for (unsigned i = 0; i < regs_written(inst); i++) {
+            for (unsigned i = 0; i < DIV_ROUND_UP(inst->size_written, 16); i++) {
                for (int c = 0; c < 4; c++) {
                   if (inst->dst.writemask & (1 << c)) {
-                     BITSET_CLEAR(live,
-                                  var_from_reg(alloc,
-                                               byte_offset(inst->dst,
-                                                           i * REG_SIZE),
-                                               c));
+                     const unsigned v = var_from_reg(alloc, inst->dst, c, i);
+                     BITSET_CLEAR(live, v);
                   }
                }
             }
@@ -137,12 +133,10 @@ vec4_visitor::dead_code_eliminate()
 
          for (int i = 0; i < 3; i++) {
             if (inst->src[i].file == VGRF) {
-               for (unsigned j = 0; j < regs_read(inst, i); j++) {
+               for (unsigned j = 0; j < DIV_ROUND_UP(inst->size_read(i), 16); j++) {
                   for (int c = 0; c < 4; c++) {
-                     BITSET_SET(live, var_from_reg(alloc,
-                                                   byte_offset(inst->src[i],
-                                                               j * REG_SIZE),
-                                                   c));
+                     const unsigned v = var_from_reg(alloc, inst->src[i], c, j);
+                     BITSET_SET(live, v);
                   }
                }
             }
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_live_variables.cpp b/src/mesa/drivers/dri/i965/brw_vec4_live_variables.cpp
index b70d6c2fab6..73f658cd8fa 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_live_variables.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_live_variables.cpp
@@ -76,12 +76,9 @@ vec4_live_variables::setup_def_use()
 	 /* Set use[] for this instruction */
 	 for (unsigned int i = 0; i < 3; i++) {
 	    if (inst->src[i].file == VGRF) {
-               for (unsigned j = 0; j < regs_read(inst, i); j++) {
+               for (unsigned j = 0; j < DIV_ROUND_UP(inst->size_read(i), 16); j++) {
                   for (int c = 0; c < 4; c++) {
-                     const unsigned v =
-                        var_from_reg(alloc,
-                                     byte_offset(inst->src[i], j * REG_SIZE),
-                                     c);
+                     const unsigned v = var_from_reg(alloc, inst->src[i], c, j);
                      if (!BITSET_TEST(bd->def, v))
                         BITSET_SET(bd->use, v);
                   }
@@ -101,12 +98,10 @@ vec4_live_variables::setup_def_use()
 	  */
 	 if (inst->dst.file == VGRF &&
 	     (!inst->predicate || inst->opcode == BRW_OPCODE_SEL)) {
-            for (unsigned i = 0; i < regs_written(inst); i++) {
+            for (unsigned i = 0; i < DIV_ROUND_UP(inst->size_written, 16); i++) {
                for (int c = 0; c < 4; c++) {
                   if (inst->dst.writemask & (1 << c)) {
-                     const unsigned v =
-                        var_from_reg(alloc,
-                                     byte_offset(inst->dst, i * REG_SIZE), c);
+                     const unsigned v = var_from_reg(alloc, inst->dst, c, i);
                      if (!BITSET_TEST(bd->use, v))
                         BITSET_SET(bd->def, v);
                   }
@@ -191,7 +186,7 @@ vec4_live_variables::vec4_live_variables(const simple_allocator &alloc,
 {
    mem_ctx = ralloc_context(NULL);
 
-   num_vars = alloc.total_size * 4;
+   num_vars = alloc.total_size * 8;
    block_data = rzalloc_array(mem_ctx, struct block_data, cfg->num_blocks);
 
    bitset_words = BITSET_WORDS(num_vars);
@@ -241,14 +236,14 @@ vec4_visitor::calculate_live_intervals()
    if (this->live_intervals)
       return;
 
-   int *start = ralloc_array(mem_ctx, int, this->alloc.total_size * 4);
-   int *end = ralloc_array(mem_ctx, int, this->alloc.total_size * 4);
+   int *start = ralloc_array(mem_ctx, int, this->alloc.total_size * 8);
+   int *end = ralloc_array(mem_ctx, int, this->alloc.total_size * 8);
    ralloc_free(this->virtual_grf_start);
    ralloc_free(this->virtual_grf_end);
    this->virtual_grf_start = start;
    this->virtual_grf_end = end;
 
-   for (unsigned i = 0; i < this->alloc.total_size * 4; i++) {
+   for (unsigned i = 0; i < this->alloc.total_size * 8; i++) {
       start[i] = MAX_INSTRUCTION;
       end[i] = -1;
    }
@@ -260,11 +255,9 @@ vec4_visitor::calculate_live_intervals()
    foreach_block_and_inst(block, vec4_instruction, inst, cfg) {
       for (unsigned int i = 0; i < 3; i++) {
 	 if (inst->src[i].file == VGRF) {
-            for (unsigned j = 0; j < regs_read(inst, i); j++) {
+            for (unsigned j = 0; j < DIV_ROUND_UP(inst->size_read(i), 16); j++) {
                for (int c = 0; c < 4; c++) {
-                  const unsigned v =
-                     var_from_reg(alloc,
-                                  byte_offset(inst->src[i], j * REG_SIZE), c);
+                  const unsigned v = var_from_reg(alloc, inst->src[i], c, j);
                   start[v] = MIN2(start[v], ip);
                   end[v] = ip;
                }
@@ -273,12 +266,10 @@ vec4_visitor::calculate_live_intervals()
       }
 
       if (inst->dst.file == VGRF) {
-         for (unsigned i = 0; i < regs_written(inst); i++) {
+         for (unsigned i = 0; i < DIV_ROUND_UP(inst->size_written, 16); i++) {
             for (int c = 0; c < 4; c++) {
                if (inst->dst.writemask & (1 << c)) {
-                  const unsigned v =
-                     var_from_reg(alloc,
-                                  byte_offset(inst->dst, i * REG_SIZE), c);
+                  const unsigned v = var_from_reg(alloc, inst->dst, c, i);
                   start[v] = MIN2(start[v], ip);
                   end[v] = ip;
                }
@@ -345,8 +336,8 @@ vec4_visitor::var_range_end(unsigned v, unsigned n) const
 bool
 vec4_visitor::virtual_grf_interferes(int a, int b)
 {
-   return !((var_range_end(4 * alloc.offsets[a], 4 * alloc.sizes[a]) <=
-             var_range_start(4 * alloc.offsets[b], 4 * alloc.sizes[b])) ||
-            (var_range_end(4 * alloc.offsets[b], 4 * alloc.sizes[b]) <=
-             var_range_start(4 * alloc.offsets[a], 4 * alloc.sizes[a])));
+   return !((var_range_end(8 * alloc.offsets[a], 8 * alloc.sizes[a]) <=
+             var_range_start(8 * alloc.offsets[b], 8 * alloc.sizes[b])) ||
+            (var_range_end(8 * alloc.offsets[b], 8 * alloc.sizes[b]) <=
+             var_range_start(8 * alloc.offsets[a], 8 * alloc.sizes[a])));
 }
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_live_variables.h b/src/mesa/drivers/dri/i965/brw_vec4_live_variables.h
index 2fbcaa1228a..8807c453743 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_live_variables.h
+++ b/src/mesa/drivers/dri/i965/brw_vec4_live_variables.h
@@ -78,23 +78,35 @@ protected:
    void *mem_ctx;
 };
 
+/* Returns the variable index for the k-th dword of the c-th component of
+ * register reg.
+ */
 inline unsigned
 var_from_reg(const simple_allocator &alloc, const src_reg &reg,
-             unsigned c = 0)
+             unsigned c = 0, unsigned k = 0)
 {
-   assert(reg.file == VGRF && reg.nr < alloc.count &&
-          reg.offset / REG_SIZE < alloc.sizes[reg.nr] && c < 4);
-   return (4 * (alloc.offsets[reg.nr] + reg.offset / REG_SIZE) +
-           BRW_GET_SWZ(reg.swizzle, c));
+   assert(reg.file == VGRF && reg.nr < alloc.count && c < 4);
+   const unsigned csize = DIV_ROUND_UP(type_sz(reg.type), 4);
+   unsigned result =
+      8 * (alloc.offsets[reg.nr] + reg.offset / REG_SIZE) +
+      (BRW_GET_SWZ(reg.swizzle, c) + k / csize * 4) * csize + k % csize;
+   /* Do not exceed the limit for this register */
+   assert(result < 8 * (alloc.offsets[reg.nr] + alloc.sizes[reg.nr]));
+   return result;
 }
 
 inline unsigned
 var_from_reg(const simple_allocator &alloc, const dst_reg &reg,
-             unsigned c = 0)
+             unsigned c = 0, unsigned k = 0)
 {
-   assert(reg.file == VGRF && reg.nr < alloc.count &&
-          reg.offset / REG_SIZE < alloc.sizes[reg.nr] && c < 4);
-   return 4 * (alloc.offsets[reg.nr] + reg.offset / REG_SIZE) + c;
+   assert(reg.file == VGRF && reg.nr < alloc.count && c < 4);
+   const unsigned csize = DIV_ROUND_UP(type_sz(reg.type), 4);
+   unsigned result =
+      8 * (alloc.offsets[reg.nr] + reg.offset / REG_SIZE) +
+      (c + k / csize * 4) * csize + k % csize;
+   /* Do not exceed the limit for this register */
+   assert(result < 8 * (alloc.offsets[reg.nr] + alloc.sizes[reg.nr]));
+   return result;
 }
 
 } /* namespace brw */