i915: Force output alpha to 1. if dst has no alpha channel.

Ensure that garbage is not stored in the unused alpha channel so that
we can rely on it being currently initialiased when used as a source or
returning via GetImage.

Partial fix for rendercheck -t blend

1 files changed, 64 insertions, 28 deletions

diff --git a/src/i915_render.c b/src/i915_render.c
index be89b55f..ad21a7cb 100644
--- a/src/i915_render.c
+++ b/src/i915_render.c
@@ -492,6 +492,7 @@ static void i915_emit_composite_setup(ScrnInfoPtr scrn)
 	uint32_t blendctl, tiling_bits;
 	Bool is_affine_src, is_affine_mask;
 	Bool is_solid_src, is_solid_mask;
+	Bool dst_has_alpha = PICT_FORMAT_A(dest_picture->format);
 	int tex_count, t;
 
 	intel->needs_render_state_emit = FALSE;
@@ -636,21 +637,40 @@ static void i915_emit_composite_setup(ScrnInfoPtr scrn)
 		}
 	    }
 
-	    /* Load the source_picture texel */
-	    if (! is_solid_src) {
-		if (is_affine_src) {
-		    i915_fs_texld(FS_R0, FS_S0, FS_T0);
-		} else {
-		    i915_fs_texldp(FS_R0, FS_S0, FS_T0);
-		}
-
-		src_reg = FS_R0;
-	    }
-
 	    if (!mask) {
-		/* No mask, so move to output color */
-		i915_fs_mov(out_reg, i915_fs_operand_reg(src_reg));
+		    /* No mask, so load directly to output color */
+		    if (! is_solid_src) {
+			    if (dst_format == COLR_BUF_8BIT)
+				    src_reg = FS_R0;
+			    else if (dst_has_alpha)
+				    src_reg = FS_OC;
+			    else
+				    src_reg = FS_R0;
+			    if (is_affine_src)
+				    i915_fs_texld(src_reg, FS_S0, FS_T0);
+			    else
+				    i915_fs_texldp(src_reg, FS_S0, FS_T0);
+		    }
+		    if (src_reg != FS_OC) {
+			    if (dst_format == COLR_BUF_8BIT)
+				    i915_fs_mov(FS_OC, i915_fs_operand(src_reg, W, W, W, W));
+			    else if (dst_has_alpha)
+				    i915_fs_mov(FS_OC, i915_fs_operand_reg(src_reg));
+			    else
+				    i915_fs_mov(FS_OC, i915_fs_operand(src_reg, X, Y, Z, ONE));
+		    }
 	    } else {
+		    if (! is_solid_src) {
+			    /* Load the source_picture texel */
+			    if (is_affine_src) {
+				    i915_fs_texld(FS_R0, FS_S0, FS_T0);
+			    } else {
+				    i915_fs_texldp(FS_R0, FS_S0, FS_T0);
+			    }
+
+			    src_reg = FS_R0;
+		    }
+
 		if (! is_solid_mask) {
 		    /* Load the mask_picture texel */
 		    if (is_affine_mask) {
@@ -673,24 +693,40 @@ static void i915_emit_composite_setup(ScrnInfoPtr scrn)
 		 * source value (src.X * mask.A).
 		 */
 		if (mask_picture->componentAlpha &&
-			PICT_FORMAT_RGB(mask_picture->format)) {
-		    if (i915_blend_op[op].src_alpha) {
-			i915_fs_mul(out_reg,
-				    i915_fs_operand(src_reg, W, W, W, W),
-				    i915_fs_operand_reg(mask_reg));
-		    } else {
-			    i915_fs_mul(out_reg,
-					i915_fs_operand_reg(src_reg),
-					i915_fs_operand_reg(mask_reg));
-		    }
+		    PICT_FORMAT_RGB(mask_picture->format)) {
+			if (i915_blend_op[op].src_alpha) {
+				if (dst_has_alpha)
+					i915_fs_mul(out_reg,
+						    i915_fs_operand(src_reg, W, W, W, W),
+						    i915_fs_operand_reg(mask_reg));
+				else
+					i915_fs_mul(out_reg,
+						    i915_fs_operand(src_reg, W, W, W, ONE),
+						    i915_fs_operand(mask_reg, X, Y, Z, ONE));
+			} else {
+				if (dst_has_alpha)
+					i915_fs_mul(out_reg,
+						    i915_fs_operand_reg(src_reg),
+						    i915_fs_operand_reg(mask_reg));
+				else
+					i915_fs_mul(out_reg,
+						    i915_fs_operand(src_reg, X, Y, Z, ONE),
+						    i915_fs_operand(mask_reg, X, Y, Z, ONE));
+			}
 		} else {
-		    i915_fs_mul(out_reg,
-				i915_fs_operand_reg(src_reg),
-				i915_fs_operand(mask_reg, W, W, W, W));
+			if (dst_has_alpha)
+				i915_fs_mul(out_reg,
+					    i915_fs_operand_reg(src_reg),
+					    i915_fs_operand(mask_reg, W, W, W, W));
+			else
+				i915_fs_mul(out_reg,
+					    i915_fs_operand(src_reg, X, Y, Z, ONE),
+					    i915_fs_operand(mask_reg, W, W, W, ONE));
 		}
+
+		if (dst_format == COLR_BUF_8BIT)
+		    i915_fs_mov(FS_OC, i915_fs_operand(out_reg, W, W, W, W));
 	    }
-	    if (dst_format == COLR_BUF_8BIT)
-		i915_fs_mov(FS_OC, i915_fs_operand(out_reg, W, W, W, W));
 
 	    FS_END();
 	}