src/mesa/shader/slang/slang_link.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  7.3
   4  *
   5  * Copyright (C) 2008  Brian Paul   All Rights Reserved.
   6  * Copyright (C) 2009  VMware, Inc.  All Rights Reserved.
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included
  16  * in all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  21  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  22  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  23  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  24  */
  25
  26 /**
  27  * \file slang_link.c
  28  * GLSL linker
  29  * \author Brian Paul
  30  */
  31
  32 #include "main/imports.h"
  33 #include "main/context.h"
  34 #include "main/hash.h"
  35 #include "main/macros.h"
  36 #include "shader/program.h"
  37 #include "shader/prog_instruction.h"
  38 #include "shader/prog_parameter.h"
  39 #include "shader/prog_print.h"
  40 #include "shader/prog_statevars.h"
  41 #include "shader/prog_uniform.h"
  42 #include "shader/shader_api.h"
  43 #include "slang_builtin.h"
  44 #include "slang_link.h"
  45
  46
  47 /** cast wrapper */
  48 static struct gl_vertex_program *
  49 vertex_program(struct gl_program *prog)
  50 {
  51    assert(prog->Target == GL_VERTEX_PROGRAM_ARB);
  52    return (struct gl_vertex_program *) prog;
  53 }
  54
  55
  56 /** cast wrapper */
  57 static struct gl_fragment_program *
  58 fragment_program(struct gl_program *prog)
  59 {
  60    assert(prog->Target == GL_FRAGMENT_PROGRAM_ARB);
  61    return (struct gl_fragment_program *) prog;
  62 }
  63
  64
  65 /**
  66  * Record a linking error.
  67  */
  68 static void
  69 link_error(struct gl_shader_program *shProg, const char *msg)
  70 {
  71    if (shProg->InfoLog) {
  72       _mesa_free(shProg->InfoLog);
  73    }
  74    shProg->InfoLog = _mesa_strdup(msg);
  75    shProg->LinkStatus = GL_FALSE;
  76 }
  77
  78
  79
  80 /**
  81  * Check if the given bit is either set or clear in both bitfields.
  82  */
  83 static GLboolean
  84 bits_agree(GLbitfield flags1, GLbitfield flags2, GLbitfield bit)
  85 {
  86    return (flags1 & bit) == (flags2 & bit);
  87 }
  88
  89
  90 /**
  91  * Linking varying vars involves rearranging varying vars so that the
  92  * vertex program's output varyings matches the order of the fragment
  93  * program's input varyings.
  94  * We'll then rewrite instructions to replace PROGRAM_VARYING with either
  95  * PROGRAM_INPUT or PROGRAM_OUTPUT depending on whether it's a vertex or
  96  * fragment shader.
  97  * This is also where we set program Input/OutputFlags to indicate
  98  * which inputs are centroid-sampled, invariant, etc.
  99  */
 100 static GLboolean
 101 link_varying_vars(GLcontext *ctx,
 102                   struct gl_shader_program *shProg, struct gl_program *prog)
 103 {
 104    GLuint *map, i, firstVarying, newFile;
 105    GLbitfield *inOutFlags;
 106
 107    map = (GLuint *) malloc(prog->Varying->NumParameters * sizeof(GLuint));
 108    if (!map)
 109       return GL_FALSE;
 110
 111    /* Varying variables are treated like other vertex program outputs
 112     * (and like other fragment program inputs).  The position of the
 113     * first varying differs for vertex/fragment programs...
 114     * Also, replace File=PROGRAM_VARYING with File=PROGRAM_INPUT/OUTPUT.
 115     */
 116    if (prog->Target == GL_VERTEX_PROGRAM_ARB) {
 117       firstVarying = VERT_RESULT_VAR0;
 118       newFile = PROGRAM_OUTPUT;
 119       inOutFlags = prog->OutputFlags;
 120    }
 121    else {
 122       assert(prog->Target == GL_FRAGMENT_PROGRAM_ARB);
 123       firstVarying = FRAG_ATTRIB_VAR0;
 124       newFile = PROGRAM_INPUT;
 125       inOutFlags = prog->InputFlags;
 126    }
 127
 128    for (i = 0; i < prog->Varying->NumParameters; i++) {
 129       /* see if this varying is in the linked varying list */
 130       const struct gl_program_parameter *var = prog->Varying->Parameters + i;
 131       GLint j = _mesa_lookup_parameter_index(shProg->Varying, -1, var->Name);
 132       if (j >= 0) {
 133          /* varying is already in list, do some error checking */
 134          const struct gl_program_parameter *v =
 135             &shProg->Varying->Parameters[j];
 136          if (var->Size != v->Size) {
 137             link_error(shProg, "mismatched varying variable types");
 138             return GL_FALSE;
 139          }
 140          if (!bits_agree(var->Flags, v->Flags, PROG_PARAM_BIT_CENTROID)) {
 141             char msg[100];
 142             _mesa_snprintf(msg, sizeof(msg),
 143                            "centroid modifier mismatch for '%s'", var->Name);
 144             link_error(shProg, msg);
 145             return GL_FALSE;
 146          }
 147          if (!bits_agree(var->Flags, v->Flags, PROG_PARAM_BIT_INVARIANT)) {
 148             char msg[100];
 149             _mesa_snprintf(msg, sizeof(msg),
 150                            "invariant modifier mismatch for '%s'", var->Name);
 151             link_error(shProg, msg);
 152             return GL_FALSE;
 153          }
 154       }
 155       else {
 156          /* not already in linked list */
 157          j = _mesa_add_varying(shProg->Varying, var->Name, var->Size,
 158                                var->Flags);
 159       }
 160
 161       if (shProg->Varying->NumParameters > ctx->Const.MaxVarying) {
 162          link_error(shProg, "Too many varying variables");
 163          return GL_FALSE;
 164       }
 165
 166       /* Map varying[i] to varying[j].
 167        * Note: the loop here takes care of arrays or large (sz>4) vars.
 168        */
 169       {
 170          GLint sz = var->Size;
 171          while (sz > 0) {
 172             inOutFlags[firstVarying + j] = var->Flags;
 173             /*printf("Link varying from %d to %d\n", i, j);*/
 174             map[i++] = j++;
 175             sz -= 4;
 176          }
 177          i--; /* go back one */
 178       }
 179    }
 180
 181
 182    /* OK, now scan the program/shader instructions looking for varying vars,
 183     * replacing the old index with the new index.
 184     */
 185    for (i = 0; i < prog->NumInstructions; i++) {
 186       struct prog_instruction *inst = prog->Instructions + i;
 187       GLuint j;
 188
 189       if (inst->DstReg.File == PROGRAM_VARYING) {
 190          inst->DstReg.File = newFile;
 191          inst->DstReg.Index = map[ inst->DstReg.Index ] + firstVarying;
 192       }
 193
 194       for (j = 0; j < 3; j++) {
 195          if (inst->SrcReg[j].File == PROGRAM_VARYING) {
 196             inst->SrcReg[j].File = newFile;
 197             inst->SrcReg[j].Index = map[ inst->SrcReg[j].Index ] + firstVarying;
 198          }
 199       }
 200    }
 201
 202    free(map);
 203
 204    /* these will get recomputed before linking is completed */
 205    prog->InputsRead = 0x0;
 206    prog->OutputsWritten = 0x0;
 207
 208    return GL_TRUE;
 209 }
 210
 211
 212 /**
 213  * Build the shProg->Uniforms list.
 214  * This is basically a list/index of all uniforms found in either/both of
 215  * the vertex and fragment shaders.
 216  *
 217  * About uniforms:
 218  * Each uniform has two indexes, one that points into the vertex
 219  * program's parameter array and another that points into the fragment
 220  * program's parameter array.  When the user changes a uniform's value
 221  * we have to change the value in the vertex and/or fragment program's
 222  * parameter array.
 223  *
 224  * This function will be called twice to set up the two uniform->parameter
 225  * mappings.
 226  *
 227  * If a uniform is only present in the vertex program OR fragment program
 228  * then the fragment/vertex parameter index, respectively, will be -1.
 229  */
 230 static GLboolean
 231 link_uniform_vars(GLcontext *ctx,
 232                   struct gl_shader_program *shProg,
 233                   struct gl_program *prog,
 234                   GLuint *numSamplers)
 235 {
 236    GLuint samplerMap[200]; /* max number of samplers declared, not used */
 237    GLuint i;
 238
 239    for (i = 0; i < prog->Parameters->NumParameters; i++) {
 240       const struct gl_program_parameter *p = prog->Parameters->Parameters + i;
 241
 242       /*
 243        * XXX FIX NEEDED HERE
 244        * We should also be adding a uniform if p->Type == PROGRAM_STATE_VAR.
 245        * For example, modelview matrix, light pos, etc.
 246        * Also, we need to update the state-var name-generator code to
 247        * generate GLSL-style names, like "gl_LightSource[0].position".
 248        * Furthermore, we'll need to fix the state-var's size/datatype info.
 249        */
 250
 251       if ((p->Type == PROGRAM_UNIFORM || p->Type == PROGRAM_SAMPLER)
 252           && p->Used) {
 253          /* add this uniform, indexing into the target's Parameters list */
 254          struct gl_uniform *uniform =
 255             _mesa_append_uniform(shProg->Uniforms, p->Name, prog->Target, i);
 256          if (uniform)
 257             uniform->Initialized = p->Initialized;
 258       }
 259
 260       /* The samplerMap[] table we build here is used to remap/re-index
 261        * sampler references by TEX instructions.
 262        */
 263       if (p->Type == PROGRAM_SAMPLER && p->Used) {
 264          /* Allocate a new sampler index */
 265          GLuint oldSampNum = (GLuint) prog->Parameters->ParameterValues[i][0];
 266          GLuint newSampNum = *numSamplers;
 267          if (newSampNum >= ctx->Const.MaxTextureImageUnits) {
 268             char s[100];
 269             _mesa_sprintf(s, "Too many texture samplers (%u, max is %u)",
 270                           newSampNum, ctx->Const.MaxTextureImageUnits);
 271             link_error(shProg, s);
 272             return GL_FALSE;
 273          }
 274          /* save old->new mapping in the table */
 275          if (oldSampNum < Elements(samplerMap))
 276             samplerMap[oldSampNum] = newSampNum;
 277          /* update parameter's sampler index */
 278          prog->Parameters->ParameterValues[i][0] = (GLfloat) newSampNum;
 279          (*numSamplers)++;
 280       }
 281    }
 282
 283    /* OK, now scan the program/shader instructions looking for texture
 284     * instructions using sampler vars.  Replace old sampler indexes with
 285     * new ones.
 286     */
 287    prog->SamplersUsed = 0x0;
 288    for (i = 0; i < prog->NumInstructions; i++) {
 289       struct prog_instruction *inst = prog->Instructions + i;
 290       if (_mesa_is_tex_instruction(inst->Opcode)) {
 291          /* here, inst->TexSrcUnit is really the sampler unit */
 292          const GLint oldSampNum = inst->TexSrcUnit;
 293
 294 #if 0
 295          printf("====== remap sampler from %d to %d\n",
 296                 inst->TexSrcUnit, samplerMap[ inst->TexSrcUnit ]);
 297 #endif
 298
 299          if (oldSampNum < Elements(samplerMap)) {
 300             const GLuint newSampNum = samplerMap[oldSampNum];
 301             inst->TexSrcUnit = newSampNum;
 302             prog->SamplerTargets[newSampNum] = inst->TexSrcTarget;
 303             prog->SamplersUsed |= (1 << newSampNum);
 304             if (inst->TexShadow) {
 305                prog->ShadowSamplers |= (1 << newSampNum);
 306             }
 307          }
 308       }
 309    }
 310
 311    return GL_TRUE;
 312 }
 313
 314
 315 /**
 316  * Resolve binding of generic vertex attributes.
 317  * For example, if the vertex shader declared "attribute vec4 foobar" we'll
 318  * allocate a generic vertex attribute for "foobar" and plug that value into
 319  * the vertex program instructions.
 320  * But if the user called glBindAttributeLocation(), those bindings will
 321  * have priority.
 322  */
 323 static GLboolean
 324 _slang_resolve_attributes(struct gl_shader_program *shProg,
 325                           const struct gl_program *origProg,
 326                           struct gl_program *linkedProg)
 327 {
 328    GLint attribMap[MAX_VERTEX_GENERIC_ATTRIBS];
 329    GLuint i, j;
 330    GLbitfield usedAttributes; /* generics only, not legacy attributes */
 331    GLbitfield inputsRead = 0x0;
 332
 333    assert(origProg != linkedProg);
 334    assert(origProg->Target == GL_VERTEX_PROGRAM_ARB);
 335    assert(linkedProg->Target == GL_VERTEX_PROGRAM_ARB);
 336
 337    if (!shProg->Attributes)
 338       shProg->Attributes = _mesa_new_parameter_list();
 339
 340    if (linkedProg->Attributes) {
 341       _mesa_free_parameter_list(linkedProg->Attributes);
 342    }
 343    linkedProg->Attributes = _mesa_new_parameter_list();
 344
 345
 346    /* Build a bitmask indicating which attribute indexes have been
 347     * explicitly bound by the user with glBindAttributeLocation().
 348     */
 349    usedAttributes = 0x0;
 350    for (i = 0; i < shProg->Attributes->NumParameters; i++) {
 351       GLint attr = shProg->Attributes->Parameters[i].StateIndexes[0];
 352       usedAttributes |= (1 << attr);
 353    }
 354
 355    /* If gl_Vertex is used, that actually counts against the limit
 356     * on generic vertex attributes.  This avoids the ambiguity of
 357     * whether glVertexAttrib4fv(0, v) sets legacy attribute 0 (vert pos)
 358     * or generic attribute[0].  If gl_Vertex is used, we want the former.
 359     */
 360    if (origProg->InputsRead & VERT_BIT_POS) {
 361       usedAttributes |= 0x1;
 362    }
 363
 364    /* initialize the generic attribute map entries to -1 */
 365    for (i = 0; i < MAX_VERTEX_GENERIC_ATTRIBS; i++) {
 366       attribMap[i] = -1;
 367    }
 368
 369    /*
 370     * Scan program for generic attribute references
 371     */
 372    for (i = 0; i < linkedProg->NumInstructions; i++) {
 373       struct prog_instruction *inst = linkedProg->Instructions + i;
 374       for (j = 0; j < 3; j++) {
 375          if (inst->SrcReg[j].File == PROGRAM_INPUT) {
 376             inputsRead |= (1 << inst->SrcReg[j].Index);
 377          }
 378
 379          if (inst->SrcReg[j].File == PROGRAM_INPUT &&
 380              inst->SrcReg[j].Index >= VERT_ATTRIB_GENERIC0) {
 381             /*
 382              * OK, we've found a generic vertex attribute reference.
 383              */
 384             const GLint k = inst->SrcReg[j].Index - VERT_ATTRIB_GENERIC0;
 385
 386             GLint attr = attribMap[k];
 387
 388             if (attr < 0) {
 389                /* Need to figure out attribute mapping now.
 390                 */
 391                const char *name = origProg->Attributes->Parameters[k].Name;
 392                const GLint size = origProg->Attributes->Parameters[k].Size;
 393                const GLenum type =origProg->Attributes->Parameters[k].DataType;
 394                GLint index;
 395
 396                /* See if there's a user-defined attribute binding for
 397                 * this name.
 398                 */
 399                index = _mesa_lookup_parameter_index(shProg->Attributes,
 400                                                     -1, name);
 401                if (index >= 0) {
 402                   /* Found a user-defined binding */
 403                   attr = shProg->Attributes->Parameters[index].StateIndexes[0];
 404                }
 405                else {
 406                   /* No user-defined binding, choose our own attribute number.
 407                    * Start at 1 since generic attribute 0 always aliases
 408                    * glVertex/position.
 409                    */
 410                   for (attr = 0; attr < MAX_VERTEX_GENERIC_ATTRIBS; attr++) {
 411                      if (((1 << attr) & usedAttributes) == 0)
 412                         break;
 413                   }
 414                   if (attr == MAX_VERTEX_GENERIC_ATTRIBS) {
 415                      link_error(shProg, "Too many vertex attributes");
 416                      return GL_FALSE;
 417                   }
 418
 419                   /* mark this attribute as used */
 420                   usedAttributes |= (1 << attr);
 421                }
 422
 423                attribMap[k] = attr;
 424
 425                /* Save the final name->attrib binding so it can be queried
 426                 * with glGetAttributeLocation().
 427                 */
 428                _mesa_add_attribute(linkedProg->Attributes, name,
 429                                    size, type, attr);
 430             }
 431
 432             assert(attr >= 0);
 433
 434             /* update the instruction's src reg */
 435             inst->SrcReg[j].Index = VERT_ATTRIB_GENERIC0 + attr;
 436          }
 437       }
 438    }
 439
 440    /* Handle pre-defined attributes here (gl_Vertex, gl_Normal, etc).
 441     * When the user queries the active attributes we need to include both
 442     * the user-defined attributes and the built-in ones.
 443     */
 444    for (i = VERT_ATTRIB_POS; i < VERT_ATTRIB_GENERIC0; i++) {
 445       if (inputsRead & (1 << i)) {
 446          _mesa_add_attribute(linkedProg->Attributes,
 447                              _slang_vert_attrib_name(i),
 448                              4, /* size in floats */
 449                              _slang_vert_attrib_type(i),
 450                              -1 /* attrib/input */);
 451       }
 452    }
 453
 454    return GL_TRUE;
 455 }
 456
 457
 458 /**
 459  * Scan program instructions to update the program's NumTemporaries field.
 460  * Note: this implemenation relies on the code generator allocating
 461  * temps in increasing order (0, 1, 2, ... ).
 462  */
 463 static void
 464 _slang_count_temporaries(struct gl_program *prog)
 465 {
 466    GLuint i, j;
 467    GLint maxIndex = -1;
 468
 469    for (i = 0; i < prog->NumInstructions; i++) {
 470       const struct prog_instruction *inst = prog->Instructions + i;
 471       const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode);
 472       for (j = 0; j < numSrc; j++) {
 473          if (inst->SrcReg[j].File == PROGRAM_TEMPORARY) {
 474             if (maxIndex < inst->SrcReg[j].Index)
 475                maxIndex = inst->SrcReg[j].Index;
 476          }
 477          if (inst->DstReg.File == PROGRAM_TEMPORARY) {
 478             if (maxIndex < (GLint) inst->DstReg.Index)
 479                maxIndex = inst->DstReg.Index;
 480          }
 481       }
 482    }
 483
 484    prog->NumTemporaries = (GLuint) (maxIndex + 1);
 485 }
 486
 487
 488 /**
 489  * Scan program instructions to update the program's InputsRead and
 490  * OutputsWritten fields.
 491  */
 492 static void
 493 _slang_update_inputs_outputs(struct gl_program *prog)
 494 {
 495    GLuint i, j;
 496    GLuint maxAddrReg = 0;
 497
 498    prog->InputsRead = 0x0;
 499    prog->OutputsWritten = 0x0;
 500
 501    for (i = 0; i < prog->NumInstructions; i++) {
 502       const struct prog_instruction *inst = prog->Instructions + i;
 503       const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode);
 504       for (j = 0; j < numSrc; j++) {
 505          if (inst->SrcReg[j].File == PROGRAM_INPUT) {
 506             prog->InputsRead |= 1 << inst->SrcReg[j].Index;
 507          }
 508          else if (inst->SrcReg[j].File == PROGRAM_ADDRESS) {
 509             maxAddrReg = MAX2(maxAddrReg, (GLuint) (inst->SrcReg[j].Index + 1));
 510          }
 511       }
 512
 513       if (inst->DstReg.File == PROGRAM_OUTPUT) {
 514          prog->OutputsWritten |= 1 << inst->DstReg.Index;
 515          if (inst->DstReg.RelAddr) {
 516             /* If the output attribute is indexed with relative addressing
 517              * we know that it must be a varying or texcoord such as
 518              * gl_TexCoord[i] = v;  In this case, mark all the texcoords
 519              * or varying outputs as being written.  It's not an error if
 520              * a vertex shader writes varying vars that aren't used by the
 521              * fragment shader.  But it is an error for a fragment shader
 522              * to use varyings that are not written by the vertex shader.
 523              */
 524             if (prog->Target == GL_VERTEX_PROGRAM_ARB) {
 525                if (inst->DstReg.Index == VERT_RESULT_TEX0) {
 526                   /* mark all texcoord outputs as written */
 527                   const GLbitfield mask =
 528                      ((1 << MAX_TEXTURE_COORD_UNITS) - 1) << VERT_RESULT_TEX0;
 529                   prog->OutputsWritten |= mask;
 530                }
 531                else if (inst->DstReg.Index == VERT_RESULT_VAR0) {
 532                   /* mark all generic varying outputs as written */
 533                   const GLbitfield mask =
 534                      ((1 << MAX_VARYING) - 1) << VERT_RESULT_VAR0;
 535                   prog->OutputsWritten |= mask;
 536                }
 537             }
 538          }
 539       }
 540       else if (inst->DstReg.File == PROGRAM_ADDRESS) {
 541          maxAddrReg = MAX2(maxAddrReg, inst->DstReg.Index + 1);
 542       }
 543    }
 544    prog->NumAddressRegs = maxAddrReg;
 545 }
 546
 547
 548
 549
 550
 551 /**
 552  * Return a new shader whose source code is the concatenation of
 553  * all the shader sources of the given type.
 554  */
 555 static struct gl_shader *
 556 concat_shaders(struct gl_shader_program *shProg, GLenum shaderType)
 557 {
 558    struct gl_shader *newShader;
 559    const struct gl_shader *firstShader = NULL;
 560    GLuint shaderLengths[100];
 561    GLchar *source;
 562    GLuint totalLen = 0, len = 0;
 563    GLuint i;
 564
 565    /* compute total size of new shader source code */
 566    for (i = 0; i < shProg->NumShaders; i++) {
 567       const struct gl_shader *shader = shProg->Shaders[i];
 568       if (shader->Type == shaderType) {
 569          shaderLengths[i] = _mesa_strlen(shader->Source);
 570          totalLen += shaderLengths[i];
 571          if (!firstShader)
 572             firstShader = shader;
 573       }
 574    }
 575
 576    if (totalLen == 0)
 577       return NULL;
 578
 579    source = (GLchar *) _mesa_malloc(totalLen + 1);
 580    if (!source)
 581       return NULL;
 582
 583    /* concatenate shaders */
 584    for (i = 0; i < shProg->NumShaders; i++) {
 585       const struct gl_shader *shader = shProg->Shaders[i];
 586       if (shader->Type == shaderType) {
 587          _mesa_memcpy(source + len, shader->Source, shaderLengths[i]);
 588          len += shaderLengths[i];
 589       }
 590    }
 591    source[len] = '\0';
 592    /*
 593    _mesa_printf("---NEW CONCATENATED SHADER---:\n%s\n------------\n", source);
 594    */
 595
 596    newShader = CALLOC_STRUCT(gl_shader);
 597    newShader->Type = shaderType;
 598    newShader->Source = source;
 599    newShader->Pragmas = firstShader->Pragmas;
 600
 601    return newShader;
 602 }
 603
 604
 605 /**
 606  * Search the shader program's list of shaders to find the one that
 607  * defines main().
 608  * This will involve shader concatenation and recompilation if needed.
 609  */
 610 static struct gl_shader *
 611 get_main_shader(GLcontext *ctx,
 612                 struct gl_shader_program *shProg, GLenum type)
 613 {
 614    struct gl_shader *shader = NULL;
 615    GLuint i;
 616
 617    /*
 618     * Look for a shader that defines main() and has no unresolved references.
 619     */
 620    for (i = 0; i < shProg->NumShaders; i++) {
 621       shader = shProg->Shaders[i];
 622       if (shader->Type == type &&
 623           shader->Main &&
 624           !shader->UnresolvedRefs) {
 625          /* All set! */
 626          return shader;
 627       }
 628    }
 629
 630    /*
 631     * There must have been unresolved references during the original
 632     * compilation.  Try concatenating all the shaders of the given type
 633     * and recompile that.
 634     */
 635    shader = concat_shaders(shProg, type);
 636
 637    if (shader) {
 638       _slang_compile(ctx, shader);
 639
 640       /* Finally, check if recompiling failed */
 641       if (!shader->CompileStatus ||
 642           !shader->Main ||
 643           shader->UnresolvedRefs) {
 644          link_error(shProg, "Unresolved symbols");
 645          return NULL;
 646       }
 647    }
 648
 649    return shader;
 650 }
 651
 652
 653 /**
 654  * Shader linker.  Currently:
 655  *
 656  * 1. The last attached vertex shader and fragment shader are linked.
 657  * 2. Varying vars in the two shaders are combined so their locations
 658  *    agree between the vertex and fragment stages.  They're treated as
 659  *    vertex program output attribs and as fragment program input attribs.
 660  * 3. The vertex and fragment programs are cloned and modified to update
 661  *    src/dst register references so they use the new, linked varying
 662  *    storage locations.
 663  */
 664 void
 665 _slang_link(GLcontext *ctx,
 666             GLhandleARB programObj,
 667             struct gl_shader_program *shProg)
 668 {
 669    const struct gl_vertex_program *vertProg = NULL;
 670    const struct gl_fragment_program *fragProg = NULL;
 671    GLuint numSamplers = 0;
 672    GLuint i;
 673
 674    _mesa_clear_shader_program_data(ctx, shProg);
 675
 676    /* Initialize LinkStatus to "success".  Will be cleared if error. */
 677    shProg->LinkStatus = GL_TRUE;
 678
 679    /* check that all programs compiled successfully */
 680    for (i = 0; i < shProg->NumShaders; i++) {
 681       if (!shProg->Shaders[i]->CompileStatus) {
 682          link_error(shProg, "linking with uncompiled shader\n");
 683          return;
 684       }
 685    }
 686
 687    shProg->Uniforms = _mesa_new_uniform_list();
 688    shProg->Varying = _mesa_new_parameter_list();
 689
 690    /*
 691     * Find the vertex and fragment shaders which define main()
 692     */
 693    {
 694       struct gl_shader *vertShader, *fragShader;
 695       vertShader = get_main_shader(ctx, shProg, GL_VERTEX_SHADER);
 696       fragShader = get_main_shader(ctx, shProg, GL_FRAGMENT_SHADER);
 697       if (vertShader)
 698          vertProg = vertex_program(vertShader->Program);
 699       if (fragShader)
 700          fragProg = fragment_program(fragShader->Program);
 701       if (!shProg->LinkStatus)
 702          return;
 703    }
 704
 705 #if FEATURE_es2_glsl
 706    /* must have both a vertex and fragment program for ES2 */
 707    if (!vertProg) {
 708       link_error(shProg, "missing vertex shader\n");
 709       return;
 710    }
 711    if (!fragProg) {
 712       link_error(shProg, "missing fragment shader\n");
 713       return;
 714    }
 715 #endif
 716
 717    /*
 718     * Make copies of the vertex/fragment programs now since we'll be
 719     * changing src/dst registers after merging the uniforms and varying vars.
 720     */
 721    _mesa_reference_vertprog(ctx, &shProg->VertexProgram, NULL);
 722    if (vertProg) {
 723       struct gl_vertex_program *linked_vprog =
 724          vertex_program(_mesa_clone_program(ctx, &vertProg->Base));
 725       shProg->VertexProgram = linked_vprog; /* refcount OK */
 726       /* vertex program ID not significant; just set Id for debugging purposes */
 727       shProg->VertexProgram->Base.Id = shProg->Name;
 728       ASSERT(shProg->VertexProgram->Base.RefCount == 1);
 729    }
 730
 731    _mesa_reference_fragprog(ctx, &shProg->FragmentProgram, NULL);
 732    if (fragProg) {
 733       struct gl_fragment_program *linked_fprog =
 734          fragment_program(_mesa_clone_program(ctx, &fragProg->Base));
 735       shProg->FragmentProgram = linked_fprog; /* refcount OK */
 736       /* vertex program ID not significant; just set Id for debugging purposes */
 737       shProg->FragmentProgram->Base.Id = shProg->Name;
 738       ASSERT(shProg->FragmentProgram->Base.RefCount == 1);
 739    }
 740
 741    /* link varying vars */
 742    if (shProg->VertexProgram) {
 743       if (!link_varying_vars(ctx, shProg, &shProg->VertexProgram->Base))
 744          return;
 745    }
 746    if (shProg->FragmentProgram) {
 747       if (!link_varying_vars(ctx, shProg, &shProg->FragmentProgram->Base))
 748          return;
 749    }
 750
 751    /* link uniform vars */
 752    if (shProg->VertexProgram) {
 753       if (!link_uniform_vars(ctx, shProg, &shProg->VertexProgram->Base,
 754                              &numSamplers)) {
 755          return;
 756       }
 757    }
 758    if (shProg->FragmentProgram) {
 759       if (!link_uniform_vars(ctx, shProg, &shProg->FragmentProgram->Base,
 760                              &numSamplers)) {
 761          return;
 762       }
 763    }
 764
 765    /*_mesa_print_uniforms(shProg->Uniforms);*/
 766
 767    if (shProg->VertexProgram) {
 768       if (!_slang_resolve_attributes(shProg, &vertProg->Base,
 769                                      &shProg->VertexProgram->Base)) {
 770          return;
 771       }
 772    }
 773
 774    if (shProg->VertexProgram) {
 775       _slang_update_inputs_outputs(&shProg->VertexProgram->Base);
 776       _slang_count_temporaries(&shProg->VertexProgram->Base);
 777       if (!(shProg->VertexProgram->Base.OutputsWritten & (1 << VERT_RESULT_HPOS))) {
 778          /* the vertex program did not compute a vertex position */
 779          link_error(shProg,
 780                     "gl_Position was not written by vertex shader\n");
 781          return;
 782       }
 783    }
 784    if (shProg->FragmentProgram) {
 785       _slang_count_temporaries(&shProg->FragmentProgram->Base);
 786       _slang_update_inputs_outputs(&shProg->FragmentProgram->Base);
 787    }
 788
 789    /* Check that all the varying vars needed by the fragment shader are
 790     * actually produced by the vertex shader.
 791     */
 792    if (shProg->FragmentProgram) {
 793       const GLbitfield varyingRead
 794          = shProg->FragmentProgram->Base.InputsRead >> FRAG_ATTRIB_VAR0;
 795       const GLbitfield varyingWritten = shProg->VertexProgram ?
 796          shProg->VertexProgram->Base.OutputsWritten >> VERT_RESULT_VAR0 : 0x0;
 797       if ((varyingRead & varyingWritten) != varyingRead) {
 798          link_error(shProg,
 799           "Fragment program using varying vars not written by vertex shader\n");
 800          return;
 801       }
 802    }
 803
 804    /* check that gl_FragColor and gl_FragData are not both written to */
 805    if (shProg->FragmentProgram) {
 806       GLbitfield outputsWritten = shProg->FragmentProgram->Base.OutputsWritten;
 807       if ((outputsWritten & ((1 << FRAG_RESULT_COLOR))) &&
 808           (outputsWritten >= (1 << FRAG_RESULT_DATA0))) {
 809          link_error(shProg, "Fragment program cannot write both gl_FragColor"
 810                     " and gl_FragData[].\n");
 811          return;
 812       }
 813    }
 814
 815
 816    if (fragProg && shProg->FragmentProgram) {
 817       /* Compute initial program's TexturesUsed info */
 818       _mesa_update_shader_textures_used(&shProg->FragmentProgram->Base);
 819
 820       /* notify driver that a new fragment program has been compiled/linked */
 821       ctx->Driver.ProgramStringNotify(ctx, GL_FRAGMENT_PROGRAM_ARB,
 822                                       &shProg->FragmentProgram->Base);
 823       if (ctx->Shader.Flags & GLSL_DUMP) {
 824          _mesa_printf("Mesa pre-link fragment program:\n");
 825          _mesa_print_program(&fragProg->Base);
 826          _mesa_print_program_parameters(ctx, &fragProg->Base);
 827
 828          _mesa_printf("Mesa post-link fragment program:\n");
 829          _mesa_print_program(&shProg->FragmentProgram->Base);
 830          _mesa_print_program_parameters(ctx, &shProg->FragmentProgram->Base);
 831       }
 832    }
 833
 834    if (vertProg && shProg->VertexProgram) {
 835       /* Compute initial program's TexturesUsed info */
 836       _mesa_update_shader_textures_used(&shProg->VertexProgram->Base);
 837
 838       /* notify driver that a new vertex program has been compiled/linked */
 839       ctx->Driver.ProgramStringNotify(ctx, GL_VERTEX_PROGRAM_ARB,
 840                                       &shProg->VertexProgram->Base);
 841       if (ctx->Shader.Flags & GLSL_DUMP) {
 842          _mesa_printf("Mesa pre-link vertex program:\n");
 843          _mesa_print_program(&vertProg->Base);
 844          _mesa_print_program_parameters(ctx, &vertProg->Base);
 845
 846          _mesa_printf("Mesa post-link vertex program:\n");
 847          _mesa_print_program(&shProg->VertexProgram->Base);
 848          _mesa_print_program_parameters(ctx, &shProg->VertexProgram->Base);
 849       }
 850    }
 851
 852    /* Debug: */
 853    if (0) {
 854       if (shProg->VertexProgram)
 855          _mesa_postprocess_program(ctx, &shProg->VertexProgram->Base);
 856       if (shProg->FragmentProgram)
 857          _mesa_postprocess_program(ctx, &shProg->FragmentProgram->Base);
 858    }
 859
 860    if (ctx->Shader.Flags & GLSL_DUMP) {
 861       _mesa_printf("Varying vars:\n");
 862       _mesa_print_parameter_list(shProg->Varying);
 863       if (shProg->InfoLog) {
 864          _mesa_printf("Info Log: %s\n", shProg->InfoLog);
 865       }
 866    }
 867
 868    shProg->LinkStatus = (shProg->VertexProgram || shProg->FragmentProgram);
 869 }
 870