amdgpu/dc: allow inlining constant int to fixed a lot better.

This uses two things that might be Linux specific,
__builtin_constant_p (might be gcc)
and
BUILD_BUG_ON. (maybe other dm's can have something similiar).

This saves 4k in the bw calcs code.
Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/calcs/bw_fixed.c

@@ -25,13 +25,6 @@
 #include "dm_services.h"
 #include "bw_fixed.h"
 
-#define BITS_PER_FRACTIONAL_PART 24
-
-#define MIN_I32 \
-	(int64_t)(-(1LL << (63 - BITS_PER_FRACTIONAL_PART)))
-
-#define MAX_I32 \
-	(int64_t)((1ULL << (63 - BITS_PER_FRACTIONAL_PART)) - 1)
 
 #define MIN_I64 \
 	(int64_t)(-(1LL << 63))
@@ -40,10 +33,7 @@
 	(int64_t)((1ULL << 63) - 1)
 
 #define FRACTIONAL_PART_MASK \
-	((1ULL << BITS_PER_FRACTIONAL_PART) - 1)
-
-#define GET_INTEGER_PART(x) \
-	((x) >> BITS_PER_FRACTIONAL_PART)
+	((1ULL << BW_FIXED_BITS_PER_FRACTIONAL_PART) - 1)
 
 #define GET_FRACTIONAL_PART(x) \
 	(FRACTIONAL_PART_MASK & (x))
@@ -56,19 +46,14 @@ static uint64_t abs_i64(int64_t arg)
 		return (uint64_t)(-arg);
 }
 
-struct bw_fixed bw_int_to_fixed(int64_t value)
+struct bw_fixed bw_int_to_fixed_nonconst(int64_t value)
 {
 	struct bw_fixed res;
-	ASSERT(value < MAX_I32 && value > MIN_I32);
-	res.value = value << BITS_PER_FRACTIONAL_PART;
+	ASSERT(value < BW_FIXED_MAX_I32 && value > BW_FIXED_MIN_I32);
+	res.value = value << BW_FIXED_BITS_PER_FRACTIONAL_PART;
 	return res;
 }
 
-int32_t bw_fixed_to_int(struct bw_fixed value)
-{
-	return GET_INTEGER_PART(value.value);
-}
-
 struct bw_fixed bw_frc_to_fixed(int64_t numerator, int64_t denominator)
 {
 	struct bw_fixed res;
@@ -87,11 +72,11 @@ struct bw_fixed bw_frc_to_fixed(int64_t numerator, int64_t denominator)
 	arg2_value = abs_i64(denominator);
 	res_value = div64_u64_rem(arg1_value, arg2_value, &remainder);
 
-	ASSERT(res_value <= MAX_I32);
+	ASSERT(res_value <= BW_FIXED_MAX_I32);
 
 	/* determine fractional part */
 	{
-		uint32_t i = BITS_PER_FRACTIONAL_PART;
+		uint32_t i = BW_FIXED_BITS_PER_FRACTIONAL_PART;
 
 		do
 		{
@@ -164,8 +149,8 @@ struct bw_fixed bw_mul(const struct bw_fixed arg1, const struct bw_fixed arg2)
 	uint64_t arg1_value = abs_i64(arg1.value);
 	uint64_t arg2_value = abs_i64(arg2.value);
 
-	uint64_t arg1_int = GET_INTEGER_PART(arg1_value);
-	uint64_t arg2_int = GET_INTEGER_PART(arg2_value);
+	uint64_t arg1_int = BW_FIXED_GET_INTEGER_PART(arg1_value);
+	uint64_t arg2_int = BW_FIXED_GET_INTEGER_PART(arg2_value);
 
 	uint64_t arg1_fra = GET_FRACTIONAL_PART(arg1_value);
 	uint64_t arg2_fra = GET_FRACTIONAL_PART(arg2_value);
@@ -174,9 +159,9 @@ struct bw_fixed bw_mul(const struct bw_fixed arg1, const struct bw_fixed arg2)
 
 	res.value = arg1_int * arg2_int;
 
-	ASSERT(res.value <= MAX_I32);
+	ASSERT(res.value <= BW_FIXED_MAX_I32);
 
-	res.value <<= BITS_PER_FRACTIONAL_PART;
+	res.value <<= BW_FIXED_BITS_PER_FRACTIONAL_PART;
 
 	tmp = arg1_int * arg2_fra;
 
@@ -192,7 +177,7 @@ struct bw_fixed bw_mul(const struct bw_fixed arg1, const struct bw_fixed arg2)
 
 	tmp = arg1_fra * arg2_fra;
 
-	tmp = (tmp >> BITS_PER_FRACTIONAL_PART) +
+	tmp = (tmp >> BW_FIXED_BITS_PER_FRACTIONAL_PART) +
 		(tmp >= (uint64_t)(bw_frc_to_fixed(1, 2).value));
 
 	ASSERT(tmp <= (uint64_t)(MAX_I64 - res.value));

drivers/gpu/drm/amd/display/dc/inc/bw_fixed.h

@@ -26,10 +26,19 @@
 #ifndef BW_FIXED_H_
 #define BW_FIXED_H_
 
+#define BW_FIXED_BITS_PER_FRACTIONAL_PART 24
+
+#define BW_FIXED_GET_INTEGER_PART(x) ((x) >> BW_FIXED_BITS_PER_FRACTIONAL_PART)
 struct bw_fixed {
 	int64_t value;
 };
 
+#define BW_FIXED_MIN_I32 \
+	(int64_t)(-(1LL << (63 - BW_FIXED_BITS_PER_FRACTIONAL_PART)))
+
+#define BW_FIXED_MAX_I32 \
+	(int64_t)((1ULL << (63 - BW_FIXED_BITS_PER_FRACTIONAL_PART)) - 1)
+
 static inline struct bw_fixed bw_min2(const struct bw_fixed arg1,
 				      const struct bw_fixed arg2)
 {
@@ -56,9 +65,22 @@ static inline struct bw_fixed bw_max3(struct bw_fixed v1,
 	return bw_max2(bw_max2(v1, v2), v3);
 }
 
-struct bw_fixed bw_int_to_fixed(int64_t value);
+struct bw_fixed bw_int_to_fixed_nonconst(int64_t value);
+static inline struct bw_fixed bw_int_to_fixed(int64_t value)
+{
+	if (__builtin_constant_p(value)) {
+		struct bw_fixed res;
+		BUILD_BUG_ON(value > BW_FIXED_MAX_I32 || value < BW_FIXED_MIN_I32);
+		res.value = value << BW_FIXED_BITS_PER_FRACTIONAL_PART;
+		return res;
+	} else
+		return bw_int_to_fixed_nonconst(value);
+}
 
-int32_t bw_fixed_to_int(struct bw_fixed value);
+static inline int32_t bw_fixed_to_int(struct bw_fixed value)
+{
+	return BW_FIXED_GET_INTEGER_PART(value.value);
+}
 
 struct bw_fixed bw_frc_to_fixed(int64_t num, int64_t denum);