r300g/compiler: add shader emulation for the alpha_to_one state

src/gallium/drivers/r300/compiler/r3xx_fragprog.c

@@ -82,8 +82,14 @@ void r3xx_compile_fragment_program(struct r300_fragment_program_compiler* c)
 {
 	int is_r500 = c->Base.is_r500;
 	int opt = !c->Base.disable_optimizations;
+	int alpha2one = c->state.alpha_to_one;
 
 	/* Lists of instruction transformations. */
+	struct radeon_program_transformation force_alpha_to_one[] = {
+		{ &rc_force_output_alpha_to_one, c },
+		{ 0, 0 }
+	};
+
 	struct radeon_program_transformation rewrite_tex[] = {
 		{ &radeonTransformTEX, c },
 		{ 0, 0 }
@@ -117,6 +123,7 @@ void r3xx_compile_fragment_program(struct r300_fragment_program_compiler* c)
 		{"unroll loops",		1, is_r500,	rc_unroll_loops,		NULL},
 		{"transform loops",		1, !is_r500,	rc_transform_loops,		NULL},
 		{"emulate branches",		1, !is_r500,	rc_emulate_branches,		NULL},
+		{"force alpha to one",		1, alpha2one,	rc_local_transform,		force_alpha_to_one},
 		{"transform TEX",		1, 1,		rc_local_transform,		rewrite_tex},
 		{"transform IF",		1, is_r500,	rc_local_transform,		rewrite_if},
 		{"native rewrite",		1, is_r500,	rc_local_transform,		native_rewrite_r500},

src/gallium/drivers/r300/compiler/radeon_code.h

@@ -182,6 +182,8 @@ struct r300_fragment_program_external_state {
 		 */
 		unsigned convert_unorm_to_snorm:1;
 	} unit[16];
+
+	unsigned alpha_to_one:1;
 };
 
 

src/gallium/drivers/r300/compiler/radeon_program_alu.c

@@ -1283,3 +1283,31 @@ void rc_transform_KILP(struct radeon_compiler * c, void *user)
 		}
 	}
 }
+
+int rc_force_output_alpha_to_one(struct radeon_compiler *c,
+				 struct rc_instruction *inst, void *data)
+{
+	struct r300_fragment_program_compiler *fragc = (struct r300_fragment_program_compiler*)c;
+	const struct rc_opcode_info *info = rc_get_opcode_info(inst->U.I.Opcode);
+	unsigned tmp;
+
+	if (!info->HasDstReg || inst->U.I.DstReg.File != RC_FILE_OUTPUT ||
+	    inst->U.I.DstReg.Index == fragc->OutputDepth)
+		return 1;
+
+	tmp = rc_find_free_temporary(c);
+
+	/* Insert MOV after inst, set alpha to 1. */
+	emit1(c, inst, RC_OPCODE_MOV, 0, inst->U.I.DstReg,
+	      srcregswz(RC_FILE_TEMPORARY, tmp, RC_SWIZZLE_XYZ1));
+
+	/* Re-route the destination of inst to the source of mov. */
+	inst->U.I.DstReg.File = RC_FILE_TEMPORARY;
+	inst->U.I.DstReg.Index = tmp;
+
+	/* Move the saturate output modifier to the MOV instruction
+	 * (for better copy propagation). */
+	inst->Next->U.I.SaturateMode = inst->U.I.SaturateMode;
+	inst->U.I.SaturateMode = RC_SATURATE_NONE;
+	return 1;
+}

src/gallium/drivers/r300/compiler/radeon_program_alu.h

@@ -63,4 +63,7 @@ int radeonTransformDeriv(
 void rc_transform_KILP(struct radeon_compiler * c,
 		       void *user);
 
+int rc_force_output_alpha_to_one(struct radeon_compiler *c,
+				 struct rc_instruction *inst, void *data);
+
 #endif /* __RADEON_PROGRAM_ALU_H_ */

src/gallium/drivers/r300/compiler/radeon_program_constants.h

@@ -126,6 +126,7 @@ typedef enum {
 
 #define RC_SWIZZLE_XYZW RC_MAKE_SWIZZLE(RC_SWIZZLE_X, RC_SWIZZLE_Y, RC_SWIZZLE_Z, RC_SWIZZLE_W)
 #define RC_SWIZZLE_XYZ0 RC_MAKE_SWIZZLE(RC_SWIZZLE_X, RC_SWIZZLE_Y, RC_SWIZZLE_Z, RC_SWIZZLE_ZERO)
+#define RC_SWIZZLE_XYZ1 RC_MAKE_SWIZZLE(RC_SWIZZLE_X, RC_SWIZZLE_Y, RC_SWIZZLE_Z, RC_SWIZZLE_ONE)
 #define RC_SWIZZLE_XYZZ RC_MAKE_SWIZZLE(RC_SWIZZLE_X, RC_SWIZZLE_Y, RC_SWIZZLE_Z, RC_SWIZZLE_Z)
 #define RC_SWIZZLE_XXXX RC_MAKE_SWIZZLE_SMEAR(RC_SWIZZLE_X)
 #define RC_SWIZZLE_YYYY RC_MAKE_SWIZZLE_SMEAR(RC_SWIZZLE_Y)