amd/common: unify cube map coordinate handling between radeonsi and radv

Code is taken from a combination of radv (for the more basic functions,
to avoid gallivm dependencies) and radeonsi (for the new and improved
derivative calculations).

v2: add 0.5 offset to tex coords only after derivative calculation

v3:
- really only touch the first three coordinates
- rebase on the removal of the 1.5 --> 0.5 offset change

Reviewed-by: Bas Nieuwenhuizen <[email protected]> (v2)
Reviewed-by: Marek Olšák <[email protected]>

1 files changed, 364 insertions, 0 deletions

diff --git a/src/amd/common/ac_llvm_util.c b/src/amd/common/ac_llvm_util.c
index a8408dd79e6..770e3bd13c1 100644
--- a/src/amd/common/ac_llvm_util.c
+++ b/src/amd/common/ac_llvm_util.c
@@ -32,6 +32,9 @@
 #include <assert.h>
 #include <stdio.h>
 
+#include "util/bitscan.h"
+#include "util/macros.h"
+
 static void ac_init_llvm_target()
 {
 #if HAVE_LLVM < 0x0307
@@ -140,3 +143,364 @@ LLVMTargetMachineRef ac_create_target_machine(enum radeon_family family)
 
 	return tm;
 }
+
+/* Initialize module-independent parts of the context.
+ *
+ * The caller is responsible for initializing ctx::module and ctx::builder.
+ */
+void
+ac_llvm_context_init(struct ac_llvm_context *ctx, LLVMContextRef context)
+{
+	LLVMValueRef args[1];
+
+	ctx->context = context;
+	ctx->module = NULL;
+	ctx->builder = NULL;
+
+	ctx->i32 = LLVMIntTypeInContext(ctx->context, 32);
+	ctx->f32 = LLVMFloatTypeInContext(ctx->context);
+
+	ctx->fpmath_md_kind = LLVMGetMDKindIDInContext(ctx->context, "fpmath", 6);
+
+	args[0] = LLVMConstReal(ctx->f32, 2.5);
+	ctx->fpmath_md_2p5_ulp = LLVMMDNodeInContext(ctx->context, args, 1);
+}
+
+#if HAVE_LLVM < 0x0400
+static LLVMAttribute ac_attr_to_llvm_attr(enum ac_func_attr attr)
+{
+   switch (attr) {
+   case AC_FUNC_ATTR_ALWAYSINLINE: return LLVMAlwaysInlineAttribute;
+   case AC_FUNC_ATTR_BYVAL: return LLVMByValAttribute;
+   case AC_FUNC_ATTR_INREG: return LLVMInRegAttribute;
+   case AC_FUNC_ATTR_NOALIAS: return LLVMNoAliasAttribute;
+   case AC_FUNC_ATTR_NOUNWIND: return LLVMNoUnwindAttribute;
+   case AC_FUNC_ATTR_READNONE: return LLVMReadNoneAttribute;
+   case AC_FUNC_ATTR_READONLY: return LLVMReadOnlyAttribute;
+   default:
+	   fprintf(stderr, "Unhandled function attribute: %x\n", attr);
+	   return 0;
+   }
+}
+
+#else
+
+static const char *attr_to_str(enum ac_func_attr attr)
+{
+   switch (attr) {
+   case AC_FUNC_ATTR_ALWAYSINLINE: return "alwaysinline";
+   case AC_FUNC_ATTR_BYVAL: return "byval";
+   case AC_FUNC_ATTR_INREG: return "inreg";
+   case AC_FUNC_ATTR_NOALIAS: return "noalias";
+   case AC_FUNC_ATTR_NOUNWIND: return "nounwind";
+   case AC_FUNC_ATTR_READNONE: return "readnone";
+   case AC_FUNC_ATTR_READONLY: return "readonly";
+   default:
+	   fprintf(stderr, "Unhandled function attribute: %x\n", attr);
+	   return 0;
+   }
+}
+
+#endif
+
+void
+ac_add_function_attr(LLVMValueRef function,
+                     int attr_idx,
+                     enum ac_func_attr attr)
+{
+
+#if HAVE_LLVM < 0x0400
+   LLVMAttribute llvm_attr = ac_attr_to_llvm_attr(attr);
+   if (attr_idx == -1) {
+      LLVMAddFunctionAttr(function, llvm_attr);
+   } else {
+      LLVMAddAttribute(LLVMGetParam(function, attr_idx - 1), llvm_attr);
+   }
+#else
+   LLVMContextRef context = LLVMGetModuleContext(LLVMGetGlobalParent(function));
+   const char *attr_name = attr_to_str(attr);
+   unsigned kind_id = LLVMGetEnumAttributeKindForName(attr_name,
+                                                      strlen(attr_name));
+   LLVMAttributeRef llvm_attr = LLVMCreateEnumAttribute(context, kind_id, 0);
+   LLVMAddAttributeAtIndex(function, attr_idx, llvm_attr);
+#endif
+}
+
+LLVMValueRef
+ac_emit_llvm_intrinsic(struct ac_llvm_context *ctx, const char *name,
+		       LLVMTypeRef return_type, LLVMValueRef *params,
+		       unsigned param_count, unsigned attrib_mask)
+{
+	LLVMValueRef function;
+
+	function = LLVMGetNamedFunction(ctx->module, name);
+	if (!function) {
+		LLVMTypeRef param_types[32], function_type;
+		unsigned i;
+
+		assert(param_count <= 32);
+
+		for (i = 0; i < param_count; ++i) {
+			assert(params[i]);
+			param_types[i] = LLVMTypeOf(params[i]);
+		}
+		function_type =
+		    LLVMFunctionType(return_type, param_types, param_count, 0);
+		function = LLVMAddFunction(ctx->module, name, function_type);
+
+		LLVMSetFunctionCallConv(function, LLVMCCallConv);
+		LLVMSetLinkage(function, LLVMExternalLinkage);
+
+		attrib_mask |= AC_FUNC_ATTR_NOUNWIND;
+		while (attrib_mask) {
+			enum ac_func_attr attr = 1u << u_bit_scan(&attrib_mask);
+			ac_add_function_attr(function, -1, attr);
+		}
+	}
+	return LLVMBuildCall(ctx->builder, function, params, param_count, "");
+}
+
+LLVMValueRef
+ac_build_gather_values_extended(struct ac_llvm_context *ctx,
+				LLVMValueRef *values,
+				unsigned value_count,
+				unsigned value_stride,
+				bool load)
+{
+	LLVMBuilderRef builder = ctx->builder;
+	LLVMValueRef vec;
+	unsigned i;
+
+
+	if (value_count == 1) {
+		if (load)
+			return LLVMBuildLoad(builder, values[0], "");
+		return values[0];
+	} else if (!value_count)
+		unreachable("value_count is 0");
+
+	for (i = 0; i < value_count; i++) {
+		LLVMValueRef value = values[i * value_stride];
+		if (load)
+			value = LLVMBuildLoad(builder, value, "");
+
+		if (!i)
+			vec = LLVMGetUndef( LLVMVectorType(LLVMTypeOf(value), value_count));
+		LLVMValueRef index = LLVMConstInt(ctx->i32, i, false);
+		vec = LLVMBuildInsertElement(builder, vec, value, index, "");
+	}
+	return vec;
+}
+
+LLVMValueRef
+ac_build_gather_values(struct ac_llvm_context *ctx,
+		       LLVMValueRef *values,
+		       unsigned value_count)
+{
+	return ac_build_gather_values_extended(ctx, values, value_count, 1, false);
+}
+
+LLVMValueRef
+ac_emit_fdiv(struct ac_llvm_context *ctx,
+	     LLVMValueRef num,
+	     LLVMValueRef den)
+{
+	LLVMValueRef ret = LLVMBuildFDiv(ctx->builder, num, den, "");
+
+	if (!LLVMIsConstant(ret))
+		LLVMSetMetadata(ret, ctx->fpmath_md_kind, ctx->fpmath_md_2p5_ulp);
+	return ret;
+}
+
+/* Coordinates for cube map selection. sc, tc, and ma are as in Table 8.27
+ * of the OpenGL 4.5 (Compatibility Profile) specification, except ma is
+ * already multiplied by two. id is the cube face number.
+ */
+struct cube_selection_coords {
+	LLVMValueRef stc[2];
+	LLVMValueRef ma;
+	LLVMValueRef id;
+};
+
+static void
+build_cube_intrinsic(struct ac_llvm_context *ctx,
+		     LLVMValueRef in[3],
+		     struct cube_selection_coords *out)
+{
+	LLVMBuilderRef builder = ctx->builder;
+
+	if (HAVE_LLVM >= 0x0309) {
+		LLVMTypeRef f32 = ctx->f32;
+
+		out->stc[1] = ac_emit_llvm_intrinsic(ctx, "llvm.amdgcn.cubetc",
+					f32, in, 3, AC_FUNC_ATTR_READNONE);
+		out->stc[0] = ac_emit_llvm_intrinsic(ctx, "llvm.amdgcn.cubesc",
+					f32, in, 3, AC_FUNC_ATTR_READNONE);
+		out->ma = ac_emit_llvm_intrinsic(ctx, "llvm.amdgcn.cubema",
+					f32, in, 3, AC_FUNC_ATTR_READNONE);
+		out->id = ac_emit_llvm_intrinsic(ctx, "llvm.amdgcn.cubeid",
+					f32, in, 3, AC_FUNC_ATTR_READNONE);
+	} else {
+		LLVMValueRef c[4] = {
+			in[0],
+			in[1],
+			in[2],
+			LLVMGetUndef(LLVMTypeOf(in[0]))
+		};
+		LLVMValueRef vec = ac_build_gather_values(ctx, c, 4);
+
+		LLVMValueRef tmp =
+			ac_emit_llvm_intrinsic(ctx, "llvm.AMDGPU.cube",
+					  LLVMTypeOf(vec), &vec, 1,
+					  AC_FUNC_ATTR_READNONE);
+
+		out->stc[1] = LLVMBuildExtractElement(builder, tmp,
+				LLVMConstInt(ctx->i32, 0, 0), "");
+		out->stc[0] = LLVMBuildExtractElement(builder, tmp,
+				LLVMConstInt(ctx->i32, 1, 0), "");
+		out->ma = LLVMBuildExtractElement(builder, tmp,
+				LLVMConstInt(ctx->i32, 2, 0), "");
+		out->id = LLVMBuildExtractElement(builder, tmp,
+				LLVMConstInt(ctx->i32, 3, 0), "");
+	}
+}
+
+/**
+ * Build a manual selection sequence for cube face sc/tc coordinates and
+ * major axis vector (multiplied by 2 for consistency) for the given
+ * vec3 \p coords, for the face implied by \p selcoords.
+ *
+ * For the major axis, we always adjust the sign to be in the direction of
+ * selcoords.ma; i.e., a positive out_ma means that coords is pointed towards
+ * the selcoords major axis.
+ */
+static void build_cube_select(LLVMBuilderRef builder,
+			      const struct cube_selection_coords *selcoords,
+			      const LLVMValueRef *coords,
+			      LLVMValueRef *out_st,
+			      LLVMValueRef *out_ma)
+{
+	LLVMTypeRef f32 = LLVMTypeOf(coords[0]);
+	LLVMValueRef is_ma_positive;
+	LLVMValueRef sgn_ma;
+	LLVMValueRef is_ma_z, is_not_ma_z;
+	LLVMValueRef is_ma_y;
+	LLVMValueRef is_ma_x;
+	LLVMValueRef sgn;
+	LLVMValueRef tmp;
+
+	is_ma_positive = LLVMBuildFCmp(builder, LLVMRealUGE,
+		selcoords->ma, LLVMConstReal(f32, 0.0), "");
+	sgn_ma = LLVMBuildSelect(builder, is_ma_positive,
+		LLVMConstReal(f32, 1.0), LLVMConstReal(f32, -1.0), "");
+
+	is_ma_z = LLVMBuildFCmp(builder, LLVMRealUGE, selcoords->id, LLVMConstReal(f32, 4.0), "");
+	is_not_ma_z = LLVMBuildNot(builder, is_ma_z, "");
+	is_ma_y = LLVMBuildAnd(builder, is_not_ma_z,
+		LLVMBuildFCmp(builder, LLVMRealUGE, selcoords->id, LLVMConstReal(f32, 2.0), ""), "");
+	is_ma_x = LLVMBuildAnd(builder, is_not_ma_z, LLVMBuildNot(builder, is_ma_y, ""), "");
+
+	/* Select sc */
+	tmp = LLVMBuildSelect(builder, is_ma_z, coords[2], coords[0], "");
+	sgn = LLVMBuildSelect(builder, is_ma_y, LLVMConstReal(f32, 1.0),
+		LLVMBuildSelect(builder, is_ma_x, sgn_ma,
+			LLVMBuildFNeg(builder, sgn_ma, ""), ""), "");
+	out_st[0] = LLVMBuildFMul(builder, tmp, sgn, "");
+
+	/* Select tc */
+	tmp = LLVMBuildSelect(builder, is_ma_y, coords[2], coords[1], "");
+	sgn = LLVMBuildSelect(builder, is_ma_y, LLVMBuildFNeg(builder, sgn_ma, ""),
+		LLVMConstReal(f32, -1.0), "");
+	out_st[1] = LLVMBuildFMul(builder, tmp, sgn, "");
+
+	/* Select ma */
+	tmp = LLVMBuildSelect(builder, is_ma_z, coords[2],
+		LLVMBuildSelect(builder, is_ma_y, coords[1], coords[0], ""), "");
+	sgn = LLVMBuildSelect(builder, is_ma_positive,
+		LLVMConstReal(f32, 2.0), LLVMConstReal(f32, -2.0), "");
+	*out_ma = LLVMBuildFMul(builder, tmp, sgn, "");
+}
+
+void
+ac_prepare_cube_coords(struct ac_llvm_context *ctx,
+		       bool is_deriv, bool is_array,
+		       LLVMValueRef *coords_arg,
+		       LLVMValueRef *derivs_arg)
+{
+
+	LLVMBuilderRef builder = ctx->builder;
+	struct cube_selection_coords selcoords;
+	LLVMValueRef coords[3];
+	LLVMValueRef invma;
+
+	build_cube_intrinsic(ctx, coords_arg, &selcoords);
+
+	invma = ac_emit_llvm_intrinsic(ctx, "llvm.fabs.f32",
+			ctx->f32, &selcoords.ma, 1, AC_FUNC_ATTR_READNONE);
+	invma = ac_emit_fdiv(ctx, LLVMConstReal(ctx->f32, 1.0), invma);
+
+	for (int i = 0; i < 2; ++i)
+		coords[i] = LLVMBuildFMul(builder, selcoords.stc[i], invma, "");
+
+	coords[2] = selcoords.id;
+
+	if (is_deriv && derivs_arg) {
+		LLVMValueRef derivs[4];
+		int axis;
+
+		/* Convert cube derivatives to 2D derivatives. */
+		for (axis = 0; axis < 2; axis++) {
+			LLVMValueRef deriv_st[2];
+			LLVMValueRef deriv_ma;
+
+			/* Transform the derivative alongside the texture
+			 * coordinate. Mathematically, the correct formula is
+			 * as follows. Assume we're projecting onto the +Z face
+			 * and denote by dx/dh the derivative of the (original)
+			 * X texture coordinate with respect to horizontal
+			 * window coordinates. The projection onto the +Z face
+			 * plane is:
+			 *
+			 *   f(x,z) = x/z
+			 *
+			 * Then df/dh = df/dx * dx/dh + df/dz * dz/dh
+			 *            = 1/z * dx/dh - x/z * 1/z * dz/dh.
+			 *
+			 * This motivatives the implementation below.
+			 *
+			 * Whether this actually gives the expected results for
+			 * apps that might feed in derivatives obtained via
+			 * finite differences is anyone's guess. The OpenGL spec
+			 * seems awfully quiet about how textureGrad for cube
+			 * maps should be handled.
+			 */
+			build_cube_select(builder, &selcoords, &derivs_arg[axis * 3],
+					  deriv_st, &deriv_ma);
+
+			deriv_ma = LLVMBuildFMul(builder, deriv_ma, invma, "");
+
+			for (int i = 0; i < 2; ++i)
+				derivs[axis * 2 + i] =
+					LLVMBuildFSub(builder,
+						LLVMBuildFMul(builder, deriv_st[i], invma, ""),
+						LLVMBuildFMul(builder, deriv_ma, coords[i], ""), "");
+		}
+
+		memcpy(derivs_arg, derivs, sizeof(derivs));
+	}
+
+	/* Shift the texture coordinate. This must be applied after the
+	 * derivative calculation.
+	 */
+	for (int i = 0; i < 2; ++i)
+		coords[i] = LLVMBuildFAdd(builder, coords[i], LLVMConstReal(ctx->f32, 1.5), "");
+
+	if (is_array) {
+		/* for cube arrays coord.z = coord.w(array_index) * 8 + face */
+		/* coords_arg.w component - array_index for cube arrays */
+		LLVMValueRef tmp = LLVMBuildFMul(ctx->builder, coords_arg[3], LLVMConstReal(ctx->f32, 8.0), "");
+		coords[2] = LLVMBuildFAdd(ctx->builder, tmp, coords[2], "");
+	}
+
+	memcpy(coords_arg, coords, sizeof(coords));
+}