Mesa (gallium-llvmpipe): llvmpipe: Clamped float to unsigned norm via mantissa manipulation.
Jose Fonseca
jrfonseca at kemper.freedesktop.org
Fri Aug 21 07:02:43 UTC 2009
Module: Mesa
Branch: gallium-llvmpipe
Commit: ce4cb74ee60c3a57cd0d0f635340c3ac15b7c4bd
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=ce4cb74ee60c3a57cd0d0f635340c3ac15b7c4bd
Author: José Fonseca <jfonseca at vmware.com>
Date: Fri Aug 21 07:35:49 2009 +0100
llvmpipe: Clamped float to unsigned norm via mantissa manipulation.
---
src/gallium/drivers/llvmpipe/lp_bld_conv.c | 119 ++++++++++++++++++++++++----
src/gallium/drivers/llvmpipe/lp_bld_conv.h | 7 ++
src/gallium/drivers/llvmpipe/lp_test.h | 4 +
3 files changed, 113 insertions(+), 17 deletions(-)
diff --git a/src/gallium/drivers/llvmpipe/lp_bld_conv.c b/src/gallium/drivers/llvmpipe/lp_bld_conv.c
index 10a8d61..520052c 100644
--- a/src/gallium/drivers/llvmpipe/lp_bld_conv.c
+++ b/src/gallium/drivers/llvmpipe/lp_bld_conv.c
@@ -46,6 +46,7 @@
#include "util/u_debug.h"
+#include "util/u_math.h"
#include "lp_bld_type.h"
#include "lp_bld_const.h"
@@ -54,6 +55,79 @@
#include "lp_bld_conv.h"
+LLVMValueRef
+lp_build_clamped_float_to_unsigned_norm(LLVMBuilderRef builder,
+ union lp_type src_type,
+ unsigned dst_width,
+ LLVMValueRef src)
+{
+ LLVMTypeRef int_vec_type = lp_build_int_vec_type(src_type);
+ LLVMValueRef res;
+ unsigned mantissa;
+ unsigned n;
+ unsigned long long ubound;
+ unsigned long long mask;
+ double scale;
+ double bias;
+
+ assert(src_type.floating);
+
+ switch(src_type.width) {
+ case 32:
+ mantissa = 23;
+ break;
+ case 64:
+ mantissa = 53;
+ break;
+ default:
+ assert(0);
+ return LLVMGetUndef(int_vec_type);
+ }
+
+ /* We cannot carry more bits than the mantissa */
+ n = MIN2(mantissa, dst_width);
+
+ /* This magic coefficients will make the desired result to appear in the
+ * lowest significant bits of the mantissa.
+ */
+ ubound = ((unsigned long long)1 << n);
+ mask = ubound - 1;
+ scale = (double)mask/ubound;
+ bias = (double)((unsigned long long)1 << (mantissa - n));
+
+ res = LLVMBuildMul(builder, src, lp_build_const_uni(src_type, scale), "");
+ res = LLVMBuildAdd(builder, res, lp_build_const_uni(src_type, bias), "");
+ res = LLVMBuildBitCast(builder, res, int_vec_type, "");
+
+ if(dst_width < src_type.width)
+ res = LLVMBuildAnd(builder, res, lp_build_int_const_uni(src_type, mask), "");
+
+ if(dst_width > n) {
+ int shift = dst_width - n;
+ res = LLVMBuildShl(builder, res, lp_build_int_const_uni(src_type, shift), "");
+
+ /* Fill in the empty lower bits for added precision? */
+#if 0
+ {
+ LLVMValueRef msb;
+ msb = LLVMBuildLShr(builder, res, lp_build_int_const_uni(src_type, dst_width - 1), "");
+ msb = LLVMBuildShl(builder, msb, lp_build_int_const_uni(src_type, shift), "");
+ msb = LLVMBuildSub(builder, msb, lp_build_int_const_uni(src_type, 1), "");
+ res = LLVMBuildOr(builder, res, msb, "");
+ }
+#elif 0
+ while(shift > 0) {
+ res = LLVMBuildOr(builder, res, LLVMBuildLShr(builder, res, lp_build_int_const_uni(src_type, n), ""), "");
+ shift -= n;
+ n *= 2;
+ }
+#endif
+ }
+
+ return res;
+}
+
+
/**
* Build shuffle vectors that match PUNPCKLxx and PUNPCKHxx instructions.
*/
@@ -259,28 +333,39 @@ lp_build_conv(LLVMBuilderRef builder,
/* Nothing to do */
}
else if(tmp_type.floating) {
- double dst_scale = lp_const_scale(dst_type);
- LLVMTypeRef tmp_vec_type;
-
- if (dst_scale != 1.0) {
- LLVMValueRef scale = lp_build_const_uni(tmp_type, dst_scale);
- for(i = 0; i < num_tmps; ++i)
- tmp[i] = LLVMBuildMul(builder, tmp[i], scale, "");
+ if(!dst_type.fixed && !dst_type.sign && dst_type.norm) {
+ for(i = 0; i < num_tmps; ++i) {
+ tmp[i] = lp_build_clamped_float_to_unsigned_norm(builder,
+ tmp_type,
+ dst_type.width,
+ tmp[i]);
+ }
+ tmp_type.floating = FALSE;
}
+ else {
+ double dst_scale = lp_const_scale(dst_type);
+ LLVMTypeRef tmp_vec_type;
+
+ if (dst_scale != 1.0) {
+ LLVMValueRef scale = lp_build_const_uni(tmp_type, dst_scale);
+ for(i = 0; i < num_tmps; ++i)
+ tmp[i] = LLVMBuildMul(builder, tmp[i], scale, "");
+ }
- /* Use an equally sized integer for intermediate computations */
- tmp_type.floating = FALSE;
- tmp_vec_type = lp_build_vec_type(tmp_type);
- for(i = 0; i < num_tmps; ++i) {
+ /* Use an equally sized integer for intermediate computations */
+ tmp_type.floating = FALSE;
+ tmp_vec_type = lp_build_vec_type(tmp_type);
+ for(i = 0; i < num_tmps; ++i) {
#if 0
- if(dst_type.sign)
- tmp[i] = LLVMBuildFPToSI(builder, tmp[i], tmp_vec_type, "");
- else
- tmp[i] = LLVMBuildFPToUI(builder, tmp[i], tmp_vec_type, "");
+ if(dst_type.sign)
+ tmp[i] = LLVMBuildFPToSI(builder, tmp[i], tmp_vec_type, "");
+ else
+ tmp[i] = LLVMBuildFPToUI(builder, tmp[i], tmp_vec_type, "");
#else
- /* FIXME: there is no SSE counterpart for LLVMBuildFPToUI */
- tmp[i] = LLVMBuildFPToSI(builder, tmp[i], tmp_vec_type, "");
+ /* FIXME: there is no SSE counterpart for LLVMBuildFPToUI */
+ tmp[i] = LLVMBuildFPToSI(builder, tmp[i], tmp_vec_type, "");
#endif
+ }
}
}
else {
diff --git a/src/gallium/drivers/llvmpipe/lp_bld_conv.h b/src/gallium/drivers/llvmpipe/lp_bld_conv.h
index 0ccd476..b1e3da7 100644
--- a/src/gallium/drivers/llvmpipe/lp_bld_conv.h
+++ b/src/gallium/drivers/llvmpipe/lp_bld_conv.h
@@ -43,6 +43,13 @@
union lp_type type;
+LLVMValueRef
+lp_build_clamped_float_to_unsigned_norm(LLVMBuilderRef builder,
+ union lp_type src_type,
+ unsigned dst_width,
+ LLVMValueRef src);
+
+
void
lp_build_conv(LLVMBuilderRef builder,
union lp_type src_type,
diff --git a/src/gallium/drivers/llvmpipe/lp_test.h b/src/gallium/drivers/llvmpipe/lp_test.h
index c51399f..69aaae2 100644
--- a/src/gallium/drivers/llvmpipe/lp_test.h
+++ b/src/gallium/drivers/llvmpipe/lp_test.h
@@ -114,6 +114,10 @@ random_vec(union lp_type type, void *dst);
boolean
+compare_vec_with_eps(union lp_type type, const void *res, const void *ref, double eps);
+
+
+boolean
compare_vec(union lp_type type, const void *res, const void *ref);
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