i965/fs: Refactor offset() into a separate function taking the width as argument.

This will be useful in the SIMD lowering pass to avoid having to
construct a builder object of the known region width just to pass it
as argument to offset(), which doesn't do anything with it other than
taking the builder dispatch_width as region width.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/mesa/drivers/dri/i965/brw_fs.h

@@ -44,23 +44,9 @@ namespace brw {
 struct brw_gs_compile;
 
 static inline fs_reg
-offset(fs_reg reg, const brw::fs_builder& bld, unsigned delta)
+offset(const fs_reg &reg, const brw::fs_builder &bld, unsigned delta)
 {
-   switch (reg.file) {
-   case BAD_FILE:
-      break;
-   case ARF:
-   case FIXED_GRF:
-   case MRF:
-   case VGRF:
-   case ATTR:
-   case UNIFORM:
-      return byte_offset(reg,
-                         delta * reg.component_size(bld.dispatch_width()));
-   case IMM:
-      assert(delta == 0);
-   }
-   return reg;
+   return offset(reg, bld.dispatch_width(), delta);
 }
 
 /**

src/mesa/drivers/dri/i965/brw_ir_fs.h

@@ -140,6 +140,25 @@ horiz_offset(const fs_reg &reg, unsigned delta)
    unreachable("Invalid register file");
 }
 
+static inline fs_reg
+offset(fs_reg reg, unsigned width, unsigned delta)
+{
+   switch (reg.file) {
+   case BAD_FILE:
+      break;
+   case ARF:
+   case FIXED_GRF:
+   case MRF:
+   case VGRF:
+   case ATTR:
+   case UNIFORM:
+      return byte_offset(reg, delta * reg.component_size(width));
+   case IMM:
+      assert(delta == 0);
+   }
+   return reg;
+}
+
 /**
  * Get the scalar channel of \p reg given by \p idx and replicate it to all
  * channels of the result.