llvmpipe: Bootstrap type conversions.

1 files changed, 190 insertions, 0 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_bld_conv.c b/src/gallium/drivers/llvmpipe/lp_bld_conv.c
new file mode 100644
index 00000000000..aea1ac25268
--- /dev/null
+++ b/src/gallium/drivers/llvmpipe/lp_bld_conv.c
@@ -0,0 +1,190 @@
+/**************************************************************************
+ *
+ * Copyright 2009 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
+ * Helper
+ *
+ * LLVM IR doesn't support all basic arithmetic operations we care about (most
+ * notably min/max and saturated operations), and it is often necessary to
+ * resort machine-specific intrinsics directly. The functions here hide all
+ * these implementation details from the other modules.
+ *
+ * We also do simple expressions simplification here. Reasons are:
+ * - it is very easy given we have all necessary information readily available
+ * - LLVM optimization passes fail to simplify several vector expressions
+ * - We often know value constraints which the optimization passes have no way
+ *   of knowing, such as when source arguments are known to be in [0, 1] range.
+ *
+ * @author Jose Fonseca <[email protected]>
+ */
+
+
+#include "util/u_debug.h"
+
+#include "lp_bld_type.h"
+#include "lp_bld_const.h"
+#include "lp_bld_intr.h"
+#include "lp_bld_conv.h"
+
+
+static LLVMValueRef
+lp_build_trunc(LLVMBuilderRef builder,
+               union lp_type src_type,
+               union lp_type dst_type,
+               LLVMValueRef *src, unsigned num_srcs)
+{
+   LLVMValueRef tmp[LP_MAX_VECTOR_LENGTH];
+   unsigned i;
+
+   /* Register width must remain constant */
+   assert(src_type.width * src_type.length == dst_type.width * dst_type.length);
+
+   /* We must not loose or gain channels. Only precision */
+   assert(src_type.length * num_srcs == dst_type.length);
+
+   for(i = 0; i < num_srcs; ++i)
+      tmp[i] = src[i];
+
+   while(src_type.width > dst_type.width) {
+      LLVMTypeRef tmp_vec_type = lp_build_vec_type(src_type);
+      union lp_type new_type = src_type;
+      LLVMTypeRef new_vec_type;
+
+      new_type.width /= 2;
+      new_type.length *= 2;
+      new_vec_type = lp_build_vec_type(new_type);
+
+      for(i = 0; i < num_srcs/2; ++i) {
+         LLVMValueRef lo = tmp[2*i + 0];
+         LLVMValueRef hi = tmp[2*i + 1];
+         LLVMValueRef packed = NULL;
+
+         if(src_type.width == 32) {
+            /* FIXME: we only have a packed signed intrinsic */
+            packed = lp_build_intrinsic_binary(builder, "llvm.x86.sse2.packssdw.128", tmp_vec_type, lo, hi);
+         }
+         else if(src_type.width == 16) {
+            if(dst_type.sign)
+               packed = lp_build_intrinsic_binary(builder, "llvm.x86.sse2.packsswb.128", tmp_vec_type, lo, hi);
+            else
+               packed = lp_build_intrinsic_binary(builder, "llvm.x86.sse2.packuswb.128", tmp_vec_type, lo, hi);
+         }
+         else
+            assert(0);
+
+         tmp[i] = LLVMBuildBitCast(builder, packed, new_vec_type, "");
+      }
+
+      src_type = new_type;
+
+      num_srcs /= 2;
+   }
+
+   assert(num_srcs == 1);
+
+   return tmp[0];
+}
+
+
+/**
+ * Convert between two SIMD types.
+ *
+ * Converting between SIMD types of different element width poses a problem:
+ * SIMD registers have a fixed number of bits, so different element widths
+ * imply different vector lengths. Therefore we must multiplex the multiple
+ * incoming sources into a single destination vector, or demux a single incoming
+ * vector into multiple vectors.
+ */
+void
+lp_build_conv(LLVMBuilderRef builder,
+              union lp_type src_type,
+              union lp_type dst_type,
+              LLVMValueRef *src, unsigned num_srcs,
+              LLVMValueRef *dst, unsigned num_dsts)
+{
+   unsigned i;
+
+   /* Register width must remain constant */
+   assert(src_type.width * src_type.length == dst_type.width * dst_type.length);
+
+   /* We must not loose or gain channels. Only precision */
+   assert(src_type.length * num_srcs == dst_type.length * num_dsts);
+
+   if(!src_type.norm && dst_type.norm) {
+      /* FIXME: clamp */
+   }
+
+   if(src_type.floating && !dst_type.floating) {
+      double dscale;
+      LLVMTypeRef tmp;
+
+      /* Rescale */
+      dscale = lp_const_scale(dst_type);
+      if (dscale != 1.0) {
+         LLVMValueRef scale = lp_build_const_uni(src_type, dscale);
+         for(i = 0; i < num_srcs; ++i)
+            src[i] = LLVMBuildMul(builder, src[i], scale, "");
+      }
+
+      /* Use an equally sized integer for intermediate computations */
+      src_type.floating = FALSE;
+      tmp = lp_build_vec_type(src_type);
+      for(i = 0; i < num_srcs; ++i) {
+#if 0
+         if(dst_type.sign)
+            src[i] = LLVMBuildFPToSI(builder, src[i], tmp, "");
+         else
+            src[i] = LLVMBuildFPToUI(builder, src[i], tmp, "");
+#else
+        /* FIXME: there is no SSE counterpart for LLVMBuildFPToUI */
+         src[i] = LLVMBuildFPToSI(builder, src[i], tmp, "");
+#endif
+      }
+   }
+   else {
+      unsigned src_shift = lp_const_shift(src_type);
+      unsigned dst_shift = lp_const_shift(dst_type);
+
+      if(src_shift > dst_shift) {
+         LLVMValueRef shift = lp_build_int_const_uni(src_type, src_shift - dst_shift);
+         for(i = 0; i < num_srcs; ++i)
+            if(dst_type.sign)
+               src[i] = LLVMBuildAShr(builder, src[i], shift, "");
+            else
+               src[i] = LLVMBuildLShr(builder, src[i], shift, "");
+      }
+   }
+
+   if(src_type.width > dst_type.width) {
+      assert(num_dsts == 1);
+      dst[0] = lp_build_trunc(builder, src_type, dst_type, src, num_srcs);
+   }
+   else
+      assert(0);
+}