[Mesa-dev] [PATCH v2 13/30] i965/fs: Fix and document component().

[Samuel Iglesias Gonsálvez]

From: Francisco Jerez <currojerez at riseup.net>

This fixes a number of bugs of component() by reimplementing it in
terms of horiz_offset(): Handling of base registers starting at a
non-zero subreg_offset, handling of strided registers and overflow of
subreg_offset into reg_offset.

Reviewed-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
---
 src/mesa/drivers/dri/i965/brw_ir_fs.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_ir_fs.h b/src/mesa/drivers/dri/i965/brw_ir_fs.h
index 305d91c..3d47b0c 100644
--- a/src/mesa/drivers/dri/i965/brw_ir_fs.h
+++ b/src/mesa/drivers/dri/i965/brw_ir_fs.h
@@ -128,11 +128,14 @@ horiz_offset(fs_reg reg, unsigned delta)
    return reg;
 }
 
+/**
+ * Get the scalar channel of \p reg given by \p idx and replicate it to all
+ * channels of the result.
+ */
 static inline fs_reg
 component(fs_reg reg, unsigned idx)
 {
-   assert(reg.subreg_offset == 0);
-   reg.subreg_offset = idx * type_sz(reg.type);
+   reg = horiz_offset(reg, idx);
    reg.stride = 0;
    return reg;
 }
-- 
2.5.0