[Mesa-dev] [PATCH] gallivm: consolidate some half-to-float and r11g11b10-to-float code
sroland at vmware.com
sroland at vmware.com
Sun Mar 24 14:59:23 PDT 2013
From: Roland Scheidegger <sroland at vmware.com>
Similar enough that we can try to use shared code.
As far as I can tell this should also fix an issue with negative
values for half-to-float conversion (not noticed in tests).
---
src/gallium/auxiliary/gallivm/lp_bld_conv.c | 46 +++-------------
src/gallium/auxiliary/gallivm/lp_bld_format.h | 9 +++
.../auxiliary/gallivm/lp_bld_format_float.c | 58 ++++++++++++--------
3 files changed, 51 insertions(+), 62 deletions(-)
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_conv.c b/src/gallium/auxiliary/gallivm/lp_bld_conv.c
index dc3649d..43c59f3 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_conv.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_conv.c
@@ -75,6 +75,7 @@
#include "lp_bld_logic.h"
#include "lp_bld_intr.h"
#include "lp_bld_printf.h"
+#include "lp_bld_format.h"
@@ -156,61 +157,28 @@ lp_build_bswap_vec(struct gallivm_state *gallivm,
/**
* Converts int16 half-float to float32
- * Note this can be performed in 1 instruction if vcvtph2ps exists (sse5 i think?)
+ * Note this can be performed in 1 instruction if vcvtph2ps exists (f16c/cvt16)
* [llvm.x86.vcvtph2ps / _mm_cvtph_ps]
*
* @param src value to convert
*
- * ref http://fgiesen.wordpress.com/2012/03/28/half-to-float-done-quic/
- * ref https://gist.github.com/2144712
*/
LLVMValueRef
lp_build_half_to_float(struct gallivm_state *gallivm,
LLVMValueRef src)
{
- int src_length = LLVMGetVectorSize(LLVMTypeOf(src));
+ LLVMBuilderRef builder = gallivm->builder;
+ LLVMTypeRef src_type = LLVMTypeOf(src);
+ unsigned src_length = LLVMGetTypeKind(src_type) == LLVMVectorTypeKind ?
+ LLVMGetVectorSize(src_type) : 1;
struct lp_type f32_type = lp_type_float_vec(32, 32 * src_length);
struct lp_type i32_type = lp_type_int_vec(32, 32 * src_length);
-
- LLVMBuilderRef builder = gallivm->builder;
LLVMTypeRef int_vec_type = lp_build_vec_type(gallivm, i32_type);
- LLVMTypeRef float_vec_type = lp_build_vec_type(gallivm, f32_type);
-
- /* Constants */
- LLVMValueRef i32_13 = lp_build_const_int_vec(gallivm, i32_type, 13);
- LLVMValueRef i32_16 = lp_build_const_int_vec(gallivm, i32_type, 16);
- LLVMValueRef i32_mask_nosign = lp_build_const_int_vec(gallivm, i32_type, 0x7fff);
- LLVMValueRef i32_was_infnan = lp_build_const_int_vec(gallivm, i32_type, 0x7bff);
- LLVMValueRef i32_exp_infnan = lp_build_const_int_vec(gallivm, i32_type, 0xff << 23);
- LLVMValueRef f32_magic = LLVMBuildBitCast(builder,
- lp_build_const_int_vec(gallivm, i32_type, (254 - 15) << 23),
- float_vec_type, "");
/* Convert int16 vector to int32 vector by zero ext */
LLVMValueRef h = LLVMBuildZExt(builder, src, int_vec_type, "");
-
- /* Exponent / mantissa bits */
- LLVMValueRef expmant = LLVMBuildAnd(builder, i32_mask_nosign, h, "");
- LLVMValueRef shifted = LLVMBuildBitCast(builder, LLVMBuildShl(builder, expmant, i32_13, ""), float_vec_type, "");
-
- /* Exponent adjust */
- LLVMValueRef scaled = LLVMBuildBitCast(builder, LLVMBuildFMul(builder, shifted, f32_magic, ""), int_vec_type, "");
-
- /* Make sure Inf/NaN survive */
- LLVMValueRef b_wasinfnan = lp_build_compare(gallivm, i32_type, PIPE_FUNC_GREATER, expmant, i32_was_infnan);
- LLVMValueRef infnanexp = LLVMBuildAnd(builder, b_wasinfnan, i32_exp_infnan, "");
-
- /* Sign bit */
- LLVMValueRef justsign = LLVMBuildXor(builder, h, expmant, "");
- LLVMValueRef sign = LLVMBuildShl(builder, justsign, i32_16, "");
-
- /* Combine result */
- LLVMValueRef sign_inf = LLVMBuildOr(builder, sign, infnanexp, "");
- LLVMValueRef final = LLVMBuildOr(builder, scaled, sign_inf, "");
-
- /* Cast from int32 vector to float32 vector */
- return LLVMBuildBitCast(builder, final, float_vec_type, "");
+ return lp_build_smallfloat_to_float(gallivm, f32_type, h, 10, 5, 0, true);
}
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_format.h b/src/gallium/auxiliary/gallivm/lp_bld_format.h
index f9ddc68..aa8c729 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_format.h
+++ b/src/gallium/auxiliary/gallivm/lp_bld_format.h
@@ -127,6 +127,15 @@ lp_build_fetch_subsampled_rgba_aos(struct gallivm_state *gallivm,
*/
LLVMValueRef
+lp_build_smallfloat_to_float(struct gallivm_state *gallivm,
+ struct lp_type f32_type,
+ LLVMValueRef src,
+ unsigned mantissa_bits,
+ unsigned exponent_bits,
+ unsigned mantissa_start,
+ boolean has_sign);
+
+LLVMValueRef
lp_build_float_to_r11g11b10(struct gallivm_state *gallivm,
LLVMValueRef *src);
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_format_float.c b/src/gallium/auxiliary/gallivm/lp_bld_format_float.c
index efab344..67e24e1 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_format_float.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_format_float.c
@@ -186,30 +186,34 @@ lp_build_float_to_r11g11b10(struct gallivm_state *gallivm,
* Convert a float-like value with less exponent and mantissa
* bits than a normal float32 to a float32. The mantissa of
* the source value is assumed to have an implied 1, and the exponent
- * is biased. There are no negative values.
- * The source value to extract must be in a 32bit int.
- * While this helper is generic, it is only ever going to be useful for
- * r11g11b10 (no other common format exists with the same properties).
+ * is biased. There may be a sign bit.
+ * The source value to extract must be in a 32bit int (bits not part of
+ * the value to convert will be masked off).
+ * This works for things like 11-bit floats or half-floats,
+ * mantissa, exponent (and sign if present) must be packed
+ * the same as they are in a ordinary float.
*
* @param src (vector) value to convert
* @param mantissa_bits the number of mantissa bits
* @param exponent_bits the number of exponent bits
* @param mantissa_start the bit start position of the packed component
+ * @param has_sign if the small float has a sign bit
*
* ref http://fgiesen.wordpress.com/2012/03/28/half-to-float-done-quic/
* ref https://gist.github.com/rygorous/2156668
*/
-static LLVMValueRef
-lp_build_smallfloat_nosign_to_float(struct gallivm_state *gallivm,
- struct lp_type f32_type,
- LLVMValueRef src,
- unsigned mantissa_bits,
- unsigned exponent_bits,
- unsigned mantissa_start)
+LLVMValueRef
+lp_build_smallfloat_to_float(struct gallivm_state *gallivm,
+ struct lp_type f32_type,
+ LLVMValueRef src,
+ unsigned mantissa_bits,
+ unsigned exponent_bits,
+ unsigned mantissa_start,
+ boolean has_sign)
{
LLVMBuilderRef builder = gallivm->builder;
LLVMValueRef smallexpmask, i32_floatexpmask, magic;
- LLVMValueRef wasinfnan, tmp, res, shift, mask;
+ LLVMValueRef wasinfnan, tmp, res, shift, maskabs, srcabs, sign;
unsigned exponent_start = mantissa_start + mantissa_bits;
struct lp_type i32_type = lp_type_int_vec(32, 32 * f32_type.length);
struct lp_build_context f32_bld, i32_bld;
@@ -226,11 +230,11 @@ lp_build_smallfloat_nosign_to_float(struct gallivm_state *gallivm,
shift = lp_build_const_int_vec(gallivm, i32_type, exponent_start - 23);
src = lp_build_shr(&i32_bld, src, shift);
}
- mask = lp_build_const_int_vec(gallivm, i32_type,
- ((1 << (mantissa_bits + exponent_bits)) - 1) <<
- (23 - mantissa_bits));
- src = lp_build_and(&i32_bld, src, mask);
- src = LLVMBuildBitCast(builder, src, f32_bld.vec_type, "");
+ maskabs = lp_build_const_int_vec(gallivm, i32_type,
+ ((1 << (mantissa_bits + exponent_bits)) - 1)
+ << (23 - mantissa_bits));
+ srcabs = lp_build_and(&i32_bld, src, maskabs);
+ srcabs = LLVMBuildBitCast(builder, srcabs, f32_bld.vec_type, "");
/* now do the actual scaling */
smallexpmask = lp_build_const_int_vec(gallivm, i32_type,
@@ -245,19 +249,27 @@ lp_build_smallfloat_nosign_to_float(struct gallivm_state *gallivm,
magic = LLVMBuildBitCast(builder, magic, f32_bld.vec_type, "");
/* adjust exponent and fix denorms */
- res = lp_build_mul(&f32_bld, src, magic);
+ res = lp_build_mul(&f32_bld, srcabs, magic);
/*
* if exp was max (== NaN or Inf) set new exp to max (keep mantissa),
* so a simple "or" will do (because exp adjust will leave mantissa intact)
*/
- /* use float compare (better for AVX 8-wide / no AVX2 though otherwise should use int) */
+ /* use float compare (better for AVX 8-wide / no AVX2 but else should use int) */
smallexpmask = LLVMBuildBitCast(builder, magic, f32_bld.vec_type, "");
- wasinfnan = lp_build_compare(gallivm, f32_type, PIPE_FUNC_GEQUAL, src, smallexpmask);
+ wasinfnan = lp_build_compare(gallivm, f32_type, PIPE_FUNC_GEQUAL, srcabs, smallexpmask);
res = LLVMBuildBitCast(builder, res, i32_bld.vec_type, "");
tmp = lp_build_and(&i32_bld, i32_floatexpmask, wasinfnan);
res = lp_build_or(&i32_bld, tmp, res);
+ if (has_sign) {
+ LLVMValueRef signmask = lp_build_const_int_vec(gallivm, i32_type, 0x80000000);
+ shift = lp_build_const_int_vec(gallivm, i32_type, 8 - exponent_bits);
+ sign = lp_build_shl(&i32_bld, src, shift);
+ sign = lp_build_and(&i32_bld, signmask, src);
+ res = lp_build_or(&i32_bld, res, sign);
+ }
+
return LLVMBuildBitCast(builder, res, f32_bld.vec_type, "");
}
@@ -278,9 +290,9 @@ lp_build_r11g11b10_to_float(struct gallivm_state *gallivm,
LLVMGetVectorSize(src_type) : 1;
struct lp_type f32_type = lp_type_float_vec(32, 32 * src_length);
- dst[0] = lp_build_smallfloat_nosign_to_float(gallivm, f32_type, src, 6, 5, 0);
- dst[1] = lp_build_smallfloat_nosign_to_float(gallivm, f32_type, src, 6, 5, 11);
- dst[2] = lp_build_smallfloat_nosign_to_float(gallivm, f32_type, src, 5, 5, 22);
+ dst[0] = lp_build_smallfloat_to_float(gallivm, f32_type, src, 6, 5, 0, false);
+ dst[1] = lp_build_smallfloat_to_float(gallivm, f32_type, src, 6, 5, 11, false);
+ dst[2] = lp_build_smallfloat_to_float(gallivm, f32_type, src, 5, 5, 22, false);
/* Just set alpha to one */
dst[3] = lp_build_one(gallivm, f32_type);
--
1.7.9.5
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