i965/brw_reg: struct constructor now needs explicit negate and abs values.

We were assuming, when constructing a new brw_reg struct, that the
negate and abs register modifiers would not be present by default in
the new register.

Now, we force explicitly setting these values when constructing a new
register.

This will avoid problems like forgetting to properly set them when we
are using a previous register to generate this new register, as it was
happening in the dFdx and dFdy generation functions.

Fixes piglit test shaders/glsl-deriv-varyings

Cc: "10.4 10.3" <mesa-stable@lists.freedesktop.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=82991
Reviewed-by: Matt Turner <mattst88@gmail.com>
(cherry picked from commit 8517e665bc4c378e8e7523827090fd1b06abaecd)

3 files changed, 28 insertions, 2 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
index 0622b0740c9..d011e77c336 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
@@ -718,12 +718,14 @@ fs_generator::generate_ddx(fs_inst *inst, struct brw_reg dst, struct brw_reg src
    }
 
    struct brw_reg src0 = brw_reg(src.file, src.nr, 1,
+                                 src.negate, src.abs,
 				 BRW_REGISTER_TYPE_F,
 				 vstride,
 				 width,
 				 BRW_HORIZONTAL_STRIDE_0,
 				 BRW_SWIZZLE_XYZW, WRITEMASK_XYZW);
    struct brw_reg src1 = brw_reg(src.file, src.nr, 0,
+                                 src.negate, src.abs,
 				 BRW_REGISTER_TYPE_F,
 				 vstride,
 				 width,
@@ -776,12 +778,14 @@ fs_generator::generate_ddy(fs_inst *inst, struct brw_reg dst, struct brw_reg src
 
       /* produce accurate derivatives */
       struct brw_reg src0 = brw_reg(src.file, src.nr, 0,
+                                    src.negate, src.abs,
                                     BRW_REGISTER_TYPE_F,
                                     BRW_VERTICAL_STRIDE_4,
                                     BRW_WIDTH_4,
                                     BRW_HORIZONTAL_STRIDE_1,
                                     BRW_SWIZZLE_XYXY, WRITEMASK_XYZW);
       struct brw_reg src1 = brw_reg(src.file, src.nr, 0,
+                                    src.negate, src.abs,
                                     BRW_REGISTER_TYPE_F,
                                     BRW_VERTICAL_STRIDE_4,
                                     BRW_WIDTH_4,
@@ -810,12 +814,14 @@ fs_generator::generate_ddy(fs_inst *inst, struct brw_reg dst, struct brw_reg src
    } else {
       /* replicate the derivative at the top-left pixel to other pixels */
       struct brw_reg src0 = brw_reg(src.file, src.nr, 0,
+                                    src.negate, src.abs,
                                     BRW_REGISTER_TYPE_F,
                                     BRW_VERTICAL_STRIDE_4,
                                     BRW_WIDTH_4,
                                     BRW_HORIZONTAL_STRIDE_0,
                                     BRW_SWIZZLE_XYZW, WRITEMASK_XYZW);
       struct brw_reg src1 = brw_reg(src.file, src.nr, 2,
+                                    src.negate, src.abs,
                                     BRW_REGISTER_TYPE_F,
                                     BRW_VERTICAL_STRIDE_4,
                                     BRW_WIDTH_4,
diff --git a/src/mesa/drivers/dri/i965/brw_reg.h b/src/mesa/drivers/dri/i965/brw_reg.h
index 19af0ae09fc..43efe0481bd 100644
--- a/src/mesa/drivers/dri/i965/brw_reg.h
+++ b/src/mesa/drivers/dri/i965/brw_reg.h
@@ -218,6 +218,8 @@ type_is_signed(unsigned type)
  * \param file      one of the BRW_x_REGISTER_FILE values
  * \param nr        register number/index
  * \param subnr     register sub number
+ * \param negate    register negate modifier
+ * \param abs       register abs modifier
  * \param type      one of BRW_REGISTER_TYPE_x
  * \param vstride   one of BRW_VERTICAL_STRIDE_x
  * \param width     one of BRW_WIDTH_x
@@ -229,6 +231,8 @@ static inline struct brw_reg
 brw_reg(unsigned file,
         unsigned nr,
         unsigned subnr,
+        unsigned negate,
+        unsigned abs,
         enum brw_reg_type type,
         unsigned vstride,
         unsigned width,
@@ -248,8 +252,8 @@ brw_reg(unsigned file,
    reg.file = file;
    reg.nr = nr;
    reg.subnr = subnr * type_sz(type);
-   reg.negate = 0;
-   reg.abs = 0;
+   reg.negate = negate;
+   reg.abs = abs;
    reg.vstride = vstride;
    reg.width = width;
    reg.hstride = hstride;
@@ -276,6 +280,8 @@ brw_vec16_reg(unsigned file, unsigned nr, unsigned subnr)
    return brw_reg(file,
                   nr,
                   subnr,
+                  0,
+                  0,
                   BRW_REGISTER_TYPE_F,
                   BRW_VERTICAL_STRIDE_16,
                   BRW_WIDTH_16,
@@ -291,6 +297,8 @@ brw_vec8_reg(unsigned file, unsigned nr, unsigned subnr)
    return brw_reg(file,
                   nr,
                   subnr,
+                  0,
+                  0,
                   BRW_REGISTER_TYPE_F,
                   BRW_VERTICAL_STRIDE_8,
                   BRW_WIDTH_8,
@@ -306,6 +314,8 @@ brw_vec4_reg(unsigned file, unsigned nr, unsigned subnr)
    return brw_reg(file,
                   nr,
                   subnr,
+                  0,
+                  0,
                   BRW_REGISTER_TYPE_F,
                   BRW_VERTICAL_STRIDE_4,
                   BRW_WIDTH_4,
@@ -321,6 +331,8 @@ brw_vec2_reg(unsigned file, unsigned nr, unsigned subnr)
    return brw_reg(file,
                   nr,
                   subnr,
+                  0,
+                  0,
                   BRW_REGISTER_TYPE_F,
                   BRW_VERTICAL_STRIDE_2,
                   BRW_WIDTH_2,
@@ -336,6 +348,8 @@ brw_vec1_reg(unsigned file, unsigned nr, unsigned subnr)
    return brw_reg(file,
                   nr,
                   subnr,
+                  0,
+                  0,
                   BRW_REGISTER_TYPE_F,
                   BRW_VERTICAL_STRIDE_0,
                   BRW_WIDTH_1,
@@ -437,6 +451,8 @@ brw_imm_reg(enum brw_reg_type type)
    return brw_reg(BRW_IMMEDIATE_VALUE,
                   0,
                   0,
+                  0,
+                  0,
                   type,
                   BRW_VERTICAL_STRIDE_0,
                   BRW_WIDTH_1,
@@ -630,6 +646,8 @@ brw_ip_reg(void)
    return brw_reg(BRW_ARCHITECTURE_REGISTER_FILE,
                   BRW_ARF_IP,
                   0,
+                  0,
+                  0,
                   BRW_REGISTER_TYPE_UD,
                   BRW_VERTICAL_STRIDE_4, /* ? */
                   BRW_WIDTH_1,
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
index df589b87c79..b56f213167c 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -1630,6 +1630,8 @@ vec4_visitor::get_timestamp()
    src_reg ts = src_reg(brw_reg(BRW_ARCHITECTURE_REGISTER_FILE,
                                 BRW_ARF_TIMESTAMP,
                                 0,
+                                0,
+                                0,
                                 BRW_REGISTER_TYPE_UD,
                                 BRW_VERTICAL_STRIDE_0,
                                 BRW_WIDTH_4,