gallivm: move code for dealing with rgb9e5 and r11g11b10 formats to own file

This is really not generic conversion stuff and the code very particular to
these formats.

4 files changed, 391 insertions, 343 deletions

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_conv.c b/src/gallium/auxiliary/gallivm/lp_bld_conv.c
index 2f39abc63d8..dc3649db363 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_conv.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_conv.c
@@ -155,335 +155,6 @@ lp_build_bswap_vec(struct gallivm_state *gallivm,
 
 
 /**
- * Convert float32 to a float-like value with less exponent and mantissa
- * bits. The mantissa is still biased, and the mantissa still has an implied 1,
- * but there's no sign bit.
- *
- * @param src             (vector) float value to convert
- * @param mantissa_bits   the number of mantissa bits
- * @param exponent_bits   the number of exponent bits
- *
- * Unlike float_to_half using accurate method here.
- * This implements round-towards-zero (trunc) hence too large numbers get
- * converted to largest representable number, not infinity.
- * Small numbers may get converted to denorms, depending on normal
- * float denorm handling of the cpu.
- * Note that compared to the references, below, we skip any rounding bias
- * since we do rounding towards zero - OpenGL allows rounding towards zero
- * (though not preferred) and DX10 even seems to require it.
- * Note that this will not do any packing - the value will
- * look like a "rescaled float" (except for Inf/NaN) but be returned
- * as int32.
- *
- * ref http://fgiesen.wordpress.com/2012/03/28/half-to-float-done-quic/
- * ref https://gist.github.com/rygorous/2156668
- */
-static LLVMValueRef
-lp_build_float_to_smallfloat_nosign(struct gallivm_state *gallivm,
-                                    struct lp_type i32_type,
-                                    LLVMValueRef src,
-                                    unsigned mantissa_bits,
-                                    unsigned exponent_bits)
-{
-   LLVMBuilderRef builder = gallivm->builder;
-   LLVMValueRef i32_floatexpmask, i32_smallexpmask, magic, normal;
-   LLVMValueRef clamped, tmp, i32_roundmask, small_max, src_abs;
-   LLVMValueRef is_nan, is_posinf, is_nan_or_posinf, i32_qnanbit, nan_or_posinf;
-   struct lp_type f32_type = lp_type_float_vec(32, 32 * i32_type.length);
-   struct lp_build_context f32_bld, i32_bld;
-   LLVMValueRef zero = lp_build_const_vec(gallivm, f32_type, 0.0f);
-
-   lp_build_context_init(&f32_bld, gallivm, f32_type);
-   lp_build_context_init(&i32_bld, gallivm, i32_type);
-
-   i32_smallexpmask = lp_build_const_int_vec(gallivm, i32_type,
-                                             ((1 << exponent_bits) - 1) << 23);
-   i32_floatexpmask = lp_build_const_int_vec(gallivm, i32_type, 0xff << 23);
-
-   /* "ordinary" number */
-   /* clamp to pos range (can still have sign bit if NaN or negative zero) */
-   clamped = lp_build_max(&f32_bld, src, zero);
-   clamped = LLVMBuildBitCast(builder, clamped, i32_bld.vec_type, "");
-   /* get rid of excess mantissa bits, and while here also potential sign bit */
-   i32_roundmask = lp_build_const_int_vec(gallivm, i32_type,
-                                          ~((1 << (23 - mantissa_bits)) - 1) |
-                                          0x7fffffff);
-
-   tmp = lp_build_and(&i32_bld, clamped, i32_roundmask);
-   tmp = LLVMBuildBitCast(builder, tmp, f32_bld.vec_type, "");
-   /* bias exponent (and denormalize if necessary) */
-   magic = lp_build_const_int_vec(gallivm, i32_type,
-                                  ((1 << (exponent_bits - 1)) - 1) << 23);
-   magic = LLVMBuildBitCast(builder, magic, f32_bld.vec_type, "");
-   normal = lp_build_mul(&f32_bld, tmp, magic);
-
-   /* clamp to max value */
-   small_max = lp_build_const_int_vec(gallivm, i32_type,
-                                      (((1 << exponent_bits) - 2) << 23) |
-                                      (((1 << mantissa_bits) - 1) << (23 - mantissa_bits)));
-   small_max = LLVMBuildBitCast(builder, small_max, f32_bld.vec_type, "");
-   normal = lp_build_min(&f32_bld, normal, small_max);
-   normal = LLVMBuildBitCast(builder, normal, i32_bld.vec_type, "");
-
-   /*
-    * handle nan/inf cases
-    * a little bit tricky since -Inf -> 0, +Inf -> +Inf, +-Nan -> +Nan
-    * Note that on a lucky day, we could simplify this a bit,
-    * by just using the max(src, zero) result - this will have -Inf
-    * clamped to 0, and MIGHT preserve the NaNs.
-    */
-   src_abs = lp_build_abs(&f32_bld, src);
-   src_abs = LLVMBuildBitCast(builder, src_abs, i32_bld.vec_type, "");
-   src = LLVMBuildBitCast(builder, src, i32_bld.vec_type, "");
-   is_nan = lp_build_compare(gallivm, i32_type, PIPE_FUNC_GREATER,
-                             src_abs, i32_floatexpmask);
-   is_posinf = lp_build_compare(gallivm, i32_type, PIPE_FUNC_EQUAL,
-                                src, i32_floatexpmask);
-   is_nan_or_posinf = lp_build_and(&i32_bld, is_nan, is_posinf);
-   /* could also set more mantissa bits but need at least the highest mantissa bit */
-   i32_qnanbit = lp_build_const_vec(gallivm, i32_type, 1 << 22);
-   /* combine maxexp with qnanbit */
-   nan_or_posinf = lp_build_or(&i32_bld, i32_smallexpmask,
-                               lp_build_and(&i32_bld, is_nan, i32_qnanbit));
-
-   return lp_build_select(&i32_bld, is_nan_or_posinf, nan_or_posinf, normal);
-}
-
-
-/**
- * Convert rgba float SoA values to packed r11g11b10 values.
- *
- * @param src   SoA float (vector) values to convert.
- */
-LLVMValueRef
-lp_build_float_to_r11g11b10(struct gallivm_state *gallivm,
-                            LLVMValueRef *src)
-{
-   LLVMValueRef dst, rcomp, bcomp, gcomp, shift, mask;
-   struct lp_build_context i32_bld;
-   LLVMTypeRef src_type = LLVMTypeOf(*src);
-   unsigned src_length = LLVMGetTypeKind(src_type) == LLVMVectorTypeKind ?
-                            LLVMGetVectorSize(src_type) : 1;
-   struct lp_type i32_type = lp_type_int_vec(32, 32 * src_length);
-
-   lp_build_context_init(&i32_bld, gallivm, i32_type);
-
-   /* "rescale" - this does the actual conversion except the packing */
-   rcomp = lp_build_float_to_smallfloat_nosign(gallivm, i32_type, src[0], 6, 5);
-   gcomp = lp_build_float_to_smallfloat_nosign(gallivm, i32_type, src[1], 6, 5);
-   bcomp = lp_build_float_to_smallfloat_nosign(gallivm, i32_type, src[2], 5, 5);
-
-   /* pack rescaled SoA floats to r11g11b10 AoS values */
-   shift = lp_build_const_int_vec(gallivm, i32_type, 23 - 6);
-   rcomp = lp_build_shr(&i32_bld, rcomp, shift);
-
-   shift = lp_build_const_int_vec(gallivm, i32_type, 23 - 17);
-   mask = lp_build_const_int_vec(gallivm, i32_type, 0x7ff << 11);
-   gcomp = lp_build_shr(&i32_bld, gcomp, shift);
-   gcomp = lp_build_and(&i32_bld, gcomp, mask);
-
-   shift = lp_build_const_int_vec(gallivm, i32_type, 27 - 23);
-   mask = lp_build_const_int_vec(gallivm, i32_type, 0x3ff << 22);
-   bcomp = lp_build_shl(&i32_bld, bcomp, shift);
-   bcomp = lp_build_and(&i32_bld, bcomp, mask);
-
-   dst = lp_build_or(&i32_bld, rcomp, gcomp);
-   return lp_build_or(&i32_bld, dst, bcomp);
-}
-
-
-/**
- * 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).
- *
- * @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
- *
- * 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)
-{
-   LLVMBuilderRef builder = gallivm->builder;
-   LLVMValueRef smallexpmask, i32_floatexpmask, magic;
-   LLVMValueRef wasinfnan, tmp, res, shift, mask;
-   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;
-
-   lp_build_context_init(&f32_bld, gallivm, f32_type);
-   lp_build_context_init(&i32_bld, gallivm, i32_type);
-
-   /* extract the component to "float position" */
-   if (exponent_start < 23) {
-      shift = lp_build_const_int_vec(gallivm, i32_type, 23 - exponent_start);
-      src = lp_build_shl(&i32_bld, src, shift);
-   }
-   else {
-      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, "");
-
-   /* now do the actual scaling */
-   smallexpmask = lp_build_const_int_vec(gallivm, i32_type,
-                                         ((1 << exponent_bits) - 1) << 23);
-   i32_floatexpmask = lp_build_const_int_vec(gallivm, i32_type, 0xff << 23);
-   /*
-    * magic number has exponent new exp bias + (new exp bias - old exp bias),
-    * mantissa is 0.
-    */
-   magic = lp_build_const_int_vec(gallivm, i32_type,
-                                  (255 - (1 << (exponent_bits - 1))) << 23);
-   magic = LLVMBuildBitCast(builder, magic, f32_bld.vec_type, "");
-
-   /* adjust exponent and fix denorms */
-   res = lp_build_mul(&f32_bld, src, 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) */
-   smallexpmask = LLVMBuildBitCast(builder, magic, f32_bld.vec_type, "");
-   wasinfnan = lp_build_compare(gallivm, f32_type, PIPE_FUNC_GEQUAL, src, 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);
-
-   return LLVMBuildBitCast(builder, res, f32_bld.vec_type, "");
-}
-
-
-/**
- * Convert packed float format (r11g11b10) value(s) to rgba float SoA values.
- *
- * @param src   packed AoS r11g11b10 values (as (vector) int32)
- * @param dst   pointer to the SoA result values
- */
-void
-lp_build_r11g11b10_to_float(struct gallivm_state *gallivm,
-                            LLVMValueRef src,
-                            LLVMValueRef *dst)
-{
-   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);
-
-   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);
-
-   /* Just set alpha to one */
-   dst[3] = lp_build_one(gallivm, f32_type);
-}
-
-
-static LLVMValueRef
-lp_build_rgb9_to_float_helper(struct gallivm_state *gallivm,
-                              struct lp_type f32_type,
-                              LLVMValueRef src,
-                              LLVMValueRef scale,
-                              unsigned mantissa_start)
-{
-   LLVMValueRef shift, mask;
-
-   struct lp_type i32_type = lp_type_int_vec(32, 32 * f32_type.length);
-   struct lp_build_context i32_bld, f32_bld;
-
-   lp_build_context_init(&i32_bld, gallivm, i32_type);
-   lp_build_context_init(&f32_bld, gallivm, f32_type);
-
-   /*
-    * This is much easier as other weirdo float formats, since
-    * there's no sign, no Inf/NaN, and there's nothing special
-    * required for normals/denormals neither (as without the implied one
-    * for the mantissa for other formats, everything looks like a denormal).
-    * So just do (float)comp_bits * scale
-    */
-   shift = lp_build_const_int_vec(gallivm, i32_type, mantissa_start);
-   mask = lp_build_const_int_vec(gallivm, i32_type, 0x1ff);
-   src = lp_build_shr(&i32_bld, src, shift);
-   src = lp_build_and(&i32_bld, src, mask);
-   src = lp_build_int_to_float(&f32_bld, src);
-   return lp_build_mul(&f32_bld, src, scale);
-}
-
-
-/**
- * Convert shared exponent format (rgb9e5) value(s) to rgba float SoA values.
- *
- * @param src   packed AoS rgb9e5 values (as (vector) int32)
- * @param dst   pointer to the SoA result values
- */
-void
-lp_build_rgb9e5_to_float(struct gallivm_state *gallivm,
-                         LLVMValueRef src,
-                         LLVMValueRef *dst)
-{
-   LLVMBuilderRef builder = gallivm->builder;
-   LLVMTypeRef src_type = LLVMTypeOf(src);
-   LLVMValueRef shift, scale, bias, exp;
-   unsigned src_length = LLVMGetTypeKind(src_type) == LLVMVectorTypeKind ?
-                            LLVMGetVectorSize(src_type) : 1;
-   struct lp_type i32_type = lp_type_int_vec(32, 32 * src_length);
-   struct lp_type u32_type = lp_type_uint_vec(32, 32 * src_length);
-   struct lp_type f32_type = lp_type_float_vec(32, 32 * src_length);
-   struct lp_build_context i32_bld, u32_bld, f32_bld;
-
-   lp_build_context_init(&i32_bld, gallivm, i32_type);
-   lp_build_context_init(&u32_bld, gallivm, u32_type);
-   lp_build_context_init(&f32_bld, gallivm, f32_type);
-
-   /* extract exponent */
-   shift = lp_build_const_int_vec(gallivm, i32_type, 27);
-   /* this shift needs to be unsigned otherwise need mask */
-   exp = lp_build_shr(&u32_bld, src, shift);
-
-   /*
-    * scale factor is 2 ^ (exp - bias)
-    * (and additionally corrected here for the mantissa bits)
-    * not using shift because
-    * a) don't have vector shift in a lot of cases
-    * b) shift direction changes hence need 2 shifts + conditional
-    *    (or rotate instruction which is even more rare (for instance XOP))
-    * so use whacky float 2 ^ function instead manipulating exponent
-    * (saves us the float conversion at the end too)
-    */
-   bias = lp_build_const_int_vec(gallivm, i32_type, 127 - (15 + 9));
-   scale = lp_build_add(&i32_bld, exp, bias);
-   shift = lp_build_const_int_vec(gallivm, i32_type, 23);
-   scale = lp_build_shl(&i32_bld, scale, shift);
-   scale = LLVMBuildBitCast(builder, scale, f32_bld.vec_type, "");
-
-   dst[0] = lp_build_rgb9_to_float_helper(gallivm, f32_type, src, scale, 0);
-   dst[1] = lp_build_rgb9_to_float_helper(gallivm, f32_type, src, scale, 9);
-   dst[2] = lp_build_rgb9_to_float_helper(gallivm, f32_type, src, scale, 18);
-
-   /* Just set alpha to one */
-   dst[3] = f32_bld.one;
-}
-
-
-/**
  * Converts int16 half-float to float32
  * Note this can be performed in 1 instruction if vcvtph2ps exists (sse5 i think?)
  * [llvm.x86.vcvtph2ps / _mm_cvtph_ps]
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_conv.h b/src/gallium/auxiliary/gallivm/lp_bld_conv.h
index d8bc294bce0..d7dfed85187 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_conv.h
+++ b/src/gallium/auxiliary/gallivm/lp_bld_conv.h
@@ -62,20 +62,6 @@ lp_build_float_to_half(struct gallivm_state *gallivm,
                        LLVMValueRef src);
 
 LLVMValueRef
-lp_build_float_to_r11g11b10(struct gallivm_state *gallivm,
-                            LLVMValueRef *src);
-
-void
-lp_build_r11g11b10_to_float(struct gallivm_state *gallivm,
-                            LLVMValueRef src,
-                            LLVMValueRef *dst);
-
-void
-lp_build_rgb9e5_to_float(struct gallivm_state *gallivm,
-                         LLVMValueRef src,
-                         LLVMValueRef *dst);
-
-LLVMValueRef
 lp_build_clamped_float_to_unsigned_norm(struct gallivm_state *gallivm,
                                         struct lp_type src_type,
                                         unsigned dst_width,
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_format.h b/src/gallium/auxiliary/gallivm/lp_bld_format.h
index 8fb173bce1e..f9ddc68d531 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_format.h
+++ b/src/gallium/auxiliary/gallivm/lp_bld_format.h
@@ -122,4 +122,22 @@ lp_build_fetch_subsampled_rgba_aos(struct gallivm_state *gallivm,
                                    LLVMValueRef i,
                                    LLVMValueRef j);
 
+/*
+ * special float formats
+ */
+
+LLVMValueRef
+lp_build_float_to_r11g11b10(struct gallivm_state *gallivm,
+                            LLVMValueRef *src);
+
+void
+lp_build_r11g11b10_to_float(struct gallivm_state *gallivm,
+                            LLVMValueRef src,
+                            LLVMValueRef *dst);
+
+void
+lp_build_rgb9e5_to_float(struct gallivm_state *gallivm,
+                         LLVMValueRef src,
+                         LLVMValueRef *dst);
+
 #endif /* !LP_BLD_FORMAT_H */
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_format_float.c b/src/gallium/auxiliary/gallivm/lp_bld_format_float.c
new file mode 100644
index 00000000000..efab344e627
--- /dev/null
+++ b/src/gallium/auxiliary/gallivm/lp_bld_format_float.c
@@ -0,0 +1,373 @@
+/**************************************************************************
+ *
+ * Copyright 2013 VMware, Inc.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+
+/**
+ * @file
+ * Format conversion code for "special" float formats.
+ *
+ * @author Roland Scheidegger <[email protected]>
+ */
+
+
+#include "util/u_debug.h"
+
+#include "lp_bld_type.h"
+#include "lp_bld_const.h"
+#include "lp_bld_arit.h"
+#include "lp_bld_bitarit.h"
+#include "lp_bld_logic.h"
+#include "lp_bld_format.h"
+
+
+/**
+ * Convert float32 to a float-like value with less exponent and mantissa
+ * bits. The mantissa is still biased, and the mantissa still has an implied 1,
+ * but there's no sign bit.
+ *
+ * @param src             (vector) float value to convert
+ * @param mantissa_bits   the number of mantissa bits
+ * @param exponent_bits   the number of exponent bits
+ *
+ * Unlike float_to_half using accurate method here.
+ * This implements round-towards-zero (trunc) hence too large numbers get
+ * converted to largest representable number, not infinity.
+ * Small numbers may get converted to denorms, depending on normal
+ * float denorm handling of the cpu.
+ * Note that compared to the references, below, we skip any rounding bias
+ * since we do rounding towards zero - OpenGL allows rounding towards zero
+ * (though not preferred) and DX10 even seems to require it.
+ * Note that this will not do any packing - the value will
+ * look like a "rescaled float" (except for Inf/NaN) but be returned
+ * as int32.
+ *
+ * ref http://fgiesen.wordpress.com/2012/03/28/half-to-float-done-quic/
+ * ref https://gist.github.com/rygorous/2156668
+ */
+static LLVMValueRef
+lp_build_float_to_smallfloat_nosign(struct gallivm_state *gallivm,
+                                    struct lp_type i32_type,
+                                    LLVMValueRef src,
+                                    unsigned mantissa_bits,
+                                    unsigned exponent_bits)
+{
+   LLVMBuilderRef builder = gallivm->builder;
+   LLVMValueRef i32_floatexpmask, i32_smallexpmask, magic, normal;
+   LLVMValueRef clamped, tmp, i32_roundmask, small_max, src_abs;
+   LLVMValueRef is_nan, is_posinf, is_nan_or_posinf, i32_qnanbit, nan_or_posinf;
+   struct lp_type f32_type = lp_type_float_vec(32, 32 * i32_type.length);
+   struct lp_build_context f32_bld, i32_bld;
+   LLVMValueRef zero = lp_build_const_vec(gallivm, f32_type, 0.0f);
+
+   lp_build_context_init(&f32_bld, gallivm, f32_type);
+   lp_build_context_init(&i32_bld, gallivm, i32_type);
+
+   i32_smallexpmask = lp_build_const_int_vec(gallivm, i32_type,
+                                             ((1 << exponent_bits) - 1) << 23);
+   i32_floatexpmask = lp_build_const_int_vec(gallivm, i32_type, 0xff << 23);
+
+   /* "ordinary" number */
+   /* clamp to pos range (can still have sign bit if NaN or negative zero) */
+   clamped = lp_build_max(&f32_bld, src, zero);
+   clamped = LLVMBuildBitCast(builder, clamped, i32_bld.vec_type, "");
+   /* get rid of excess mantissa bits, and while here also potential sign bit */
+   i32_roundmask = lp_build_const_int_vec(gallivm, i32_type,
+                                          ~((1 << (23 - mantissa_bits)) - 1) |
+                                          0x7fffffff);
+
+   tmp = lp_build_and(&i32_bld, clamped, i32_roundmask);
+   tmp = LLVMBuildBitCast(builder, tmp, f32_bld.vec_type, "");
+   /* bias exponent (and denormalize if necessary) */
+   magic = lp_build_const_int_vec(gallivm, i32_type,
+                                  ((1 << (exponent_bits - 1)) - 1) << 23);
+   magic = LLVMBuildBitCast(builder, magic, f32_bld.vec_type, "");
+   normal = lp_build_mul(&f32_bld, tmp, magic);
+
+   /* clamp to max value */
+   small_max = lp_build_const_int_vec(gallivm, i32_type,
+                                      (((1 << exponent_bits) - 2) << 23) |
+                                      (((1 << mantissa_bits) - 1) << (23 - mantissa_bits)));
+   small_max = LLVMBuildBitCast(builder, small_max, f32_bld.vec_type, "");
+   normal = lp_build_min(&f32_bld, normal, small_max);
+   normal = LLVMBuildBitCast(builder, normal, i32_bld.vec_type, "");
+
+   /*
+    * handle nan/inf cases
+    * a little bit tricky since -Inf -> 0, +Inf -> +Inf, +-Nan -> +Nan
+    * Note that on a lucky day, we could simplify this a bit,
+    * by just using the max(src, zero) result - this will have -Inf
+    * clamped to 0, and MIGHT preserve the NaNs.
+    */
+   src_abs = lp_build_abs(&f32_bld, src);
+   src_abs = LLVMBuildBitCast(builder, src_abs, i32_bld.vec_type, "");
+   src = LLVMBuildBitCast(builder, src, i32_bld.vec_type, "");
+   is_nan = lp_build_compare(gallivm, i32_type, PIPE_FUNC_GREATER,
+                             src_abs, i32_floatexpmask);
+   is_posinf = lp_build_compare(gallivm, i32_type, PIPE_FUNC_EQUAL,
+                                src, i32_floatexpmask);
+   is_nan_or_posinf = lp_build_and(&i32_bld, is_nan, is_posinf);
+   /* could also set more mantissa bits but need at least the highest mantissa bit */
+   i32_qnanbit = lp_build_const_vec(gallivm, i32_type, 1 << 22);
+   /* combine maxexp with qnanbit */
+   nan_or_posinf = lp_build_or(&i32_bld, i32_smallexpmask,
+                               lp_build_and(&i32_bld, is_nan, i32_qnanbit));
+
+   return lp_build_select(&i32_bld, is_nan_or_posinf, nan_or_posinf, normal);
+}
+
+
+/**
+ * Convert rgba float SoA values to packed r11g11b10 values.
+ *
+ * @param src   SoA float (vector) values to convert.
+ */
+LLVMValueRef
+lp_build_float_to_r11g11b10(struct gallivm_state *gallivm,
+                            LLVMValueRef *src)
+{
+   LLVMValueRef dst, rcomp, bcomp, gcomp, shift, mask;
+   struct lp_build_context i32_bld;
+   LLVMTypeRef src_type = LLVMTypeOf(*src);
+   unsigned src_length = LLVMGetTypeKind(src_type) == LLVMVectorTypeKind ?
+                            LLVMGetVectorSize(src_type) : 1;
+   struct lp_type i32_type = lp_type_int_vec(32, 32 * src_length);
+
+   lp_build_context_init(&i32_bld, gallivm, i32_type);
+
+   /* "rescale" - this does the actual conversion except the packing */
+   rcomp = lp_build_float_to_smallfloat_nosign(gallivm, i32_type, src[0], 6, 5);
+   gcomp = lp_build_float_to_smallfloat_nosign(gallivm, i32_type, src[1], 6, 5);
+   bcomp = lp_build_float_to_smallfloat_nosign(gallivm, i32_type, src[2], 5, 5);
+
+   /* pack rescaled SoA floats to r11g11b10 AoS values */
+   shift = lp_build_const_int_vec(gallivm, i32_type, 23 - 6);
+   rcomp = lp_build_shr(&i32_bld, rcomp, shift);
+
+   shift = lp_build_const_int_vec(gallivm, i32_type, 23 - 17);
+   mask = lp_build_const_int_vec(gallivm, i32_type, 0x7ff << 11);
+   gcomp = lp_build_shr(&i32_bld, gcomp, shift);
+   gcomp = lp_build_and(&i32_bld, gcomp, mask);
+
+   shift = lp_build_const_int_vec(gallivm, i32_type, 27 - 23);
+   mask = lp_build_const_int_vec(gallivm, i32_type, 0x3ff << 22);
+   bcomp = lp_build_shl(&i32_bld, bcomp, shift);
+   bcomp = lp_build_and(&i32_bld, bcomp, mask);
+
+   dst = lp_build_or(&i32_bld, rcomp, gcomp);
+   return lp_build_or(&i32_bld, dst, bcomp);
+}
+
+
+/**
+ * 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).
+ *
+ * @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
+ *
+ * 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)
+{
+   LLVMBuilderRef builder = gallivm->builder;
+   LLVMValueRef smallexpmask, i32_floatexpmask, magic;
+   LLVMValueRef wasinfnan, tmp, res, shift, mask;
+   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;
+
+   lp_build_context_init(&f32_bld, gallivm, f32_type);
+   lp_build_context_init(&i32_bld, gallivm, i32_type);
+
+   /* extract the component to "float position" */
+   if (exponent_start < 23) {
+      shift = lp_build_const_int_vec(gallivm, i32_type, 23 - exponent_start);
+      src = lp_build_shl(&i32_bld, src, shift);
+   }
+   else {
+      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, "");
+
+   /* now do the actual scaling */
+   smallexpmask = lp_build_const_int_vec(gallivm, i32_type,
+                                         ((1 << exponent_bits) - 1) << 23);
+   i32_floatexpmask = lp_build_const_int_vec(gallivm, i32_type, 0xff << 23);
+   /*
+    * magic number has exponent new exp bias + (new exp bias - old exp bias),
+    * mantissa is 0.
+    */
+   magic = lp_build_const_int_vec(gallivm, i32_type,
+                                  (255 - (1 << (exponent_bits - 1))) << 23);
+   magic = LLVMBuildBitCast(builder, magic, f32_bld.vec_type, "");
+
+   /* adjust exponent and fix denorms */
+   res = lp_build_mul(&f32_bld, src, 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) */
+   smallexpmask = LLVMBuildBitCast(builder, magic, f32_bld.vec_type, "");
+   wasinfnan = lp_build_compare(gallivm, f32_type, PIPE_FUNC_GEQUAL, src, 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);
+
+   return LLVMBuildBitCast(builder, res, f32_bld.vec_type, "");
+}
+
+
+/**
+ * Convert packed float format (r11g11b10) value(s) to rgba float SoA values.
+ *
+ * @param src   packed AoS r11g11b10 values (as (vector) int32)
+ * @param dst   pointer to the SoA result values
+ */
+void
+lp_build_r11g11b10_to_float(struct gallivm_state *gallivm,
+                            LLVMValueRef src,
+                            LLVMValueRef *dst)
+{
+   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);
+
+   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);
+
+   /* Just set alpha to one */
+   dst[3] = lp_build_one(gallivm, f32_type);
+}
+
+
+static LLVMValueRef
+lp_build_rgb9_to_float_helper(struct gallivm_state *gallivm,
+                              struct lp_type f32_type,
+                              LLVMValueRef src,
+                              LLVMValueRef scale,
+                              unsigned mantissa_start)
+{
+   LLVMValueRef shift, mask;
+
+   struct lp_type i32_type = lp_type_int_vec(32, 32 * f32_type.length);
+   struct lp_build_context i32_bld, f32_bld;
+
+   lp_build_context_init(&i32_bld, gallivm, i32_type);
+   lp_build_context_init(&f32_bld, gallivm, f32_type);
+
+   /*
+    * This is much easier as other weirdo float formats, since
+    * there's no sign, no Inf/NaN, and there's nothing special
+    * required for normals/denormals neither (as without the implied one
+    * for the mantissa for other formats, everything looks like a denormal).
+    * So just do (float)comp_bits * scale
+    */
+   shift = lp_build_const_int_vec(gallivm, i32_type, mantissa_start);
+   mask = lp_build_const_int_vec(gallivm, i32_type, 0x1ff);
+   src = lp_build_shr(&i32_bld, src, shift);
+   src = lp_build_and(&i32_bld, src, mask);
+   src = lp_build_int_to_float(&f32_bld, src);
+   return lp_build_mul(&f32_bld, src, scale);
+}
+
+
+/**
+ * Convert shared exponent format (rgb9e5) value(s) to rgba float SoA values.
+ *
+ * @param src   packed AoS rgb9e5 values (as (vector) int32)
+ * @param dst   pointer to the SoA result values
+ */
+void
+lp_build_rgb9e5_to_float(struct gallivm_state *gallivm,
+                         LLVMValueRef src,
+                         LLVMValueRef *dst)
+{
+   LLVMBuilderRef builder = gallivm->builder;
+   LLVMTypeRef src_type = LLVMTypeOf(src);
+   LLVMValueRef shift, scale, bias, exp;
+   unsigned src_length = LLVMGetTypeKind(src_type) == LLVMVectorTypeKind ?
+                            LLVMGetVectorSize(src_type) : 1;
+   struct lp_type i32_type = lp_type_int_vec(32, 32 * src_length);
+   struct lp_type u32_type = lp_type_uint_vec(32, 32 * src_length);
+   struct lp_type f32_type = lp_type_float_vec(32, 32 * src_length);
+   struct lp_build_context i32_bld, u32_bld, f32_bld;
+
+   lp_build_context_init(&i32_bld, gallivm, i32_type);
+   lp_build_context_init(&u32_bld, gallivm, u32_type);
+   lp_build_context_init(&f32_bld, gallivm, f32_type);
+
+   /* extract exponent */
+   shift = lp_build_const_int_vec(gallivm, i32_type, 27);
+   /* this shift needs to be unsigned otherwise need mask */
+   exp = lp_build_shr(&u32_bld, src, shift);
+
+   /*
+    * scale factor is 2 ^ (exp - bias)
+    * (and additionally corrected here for the mantissa bits)
+    * not using shift because
+    * a) don't have vector shift in a lot of cases
+    * b) shift direction changes hence need 2 shifts + conditional
+    *    (or rotate instruction which is even more rare (for instance XOP))
+    * so use whacky float 2 ^ function instead manipulating exponent
+    * (saves us the float conversion at the end too)
+    */
+   bias = lp_build_const_int_vec(gallivm, i32_type, 127 - (15 + 9));
+   scale = lp_build_add(&i32_bld, exp, bias);
+   shift = lp_build_const_int_vec(gallivm, i32_type, 23);
+   scale = lp_build_shl(&i32_bld, scale, shift);
+   scale = LLVMBuildBitCast(builder, scale, f32_bld.vec_type, "");
+
+   dst[0] = lp_build_rgb9_to_float_helper(gallivm, f32_type, src, scale, 0);
+   dst[1] = lp_build_rgb9_to_float_helper(gallivm, f32_type, src, scale, 9);
+   dst[2] = lp_build_rgb9_to_float_helper(gallivm, f32_type, src, scale, 18);
+
+   /* Just set alpha to one */
+   dst[3] = f32_bld.one;
+}