diff options
Diffstat (limited to 'src/mesa/program/prog_optimize.c')
| -rw-r--r-- | src/mesa/program/prog_optimize.c | 1041 |
1 files changed, 1041 insertions, 0 deletions
diff --git a/src/mesa/program/prog_optimize.c b/src/mesa/program/prog_optimize.c new file mode 100644 index 00000000000..bd120b8643c --- /dev/null +++ b/src/mesa/program/prog_optimize.c @@ -0,0 +1,1041 @@ +/* + * Mesa 3-D graphics library + * Version: 7.5 + * + * Copyright (C) 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, sublicense, + * 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 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 NONINFRINGEMENT. IN NO EVENT SHALL + * VMWARE 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. + */ + + + +#include "main/glheader.h" +#include "main/context.h" +#include "main/macros.h" +#include "program.h" +#include "prog_instruction.h" +#include "prog_optimize.h" +#include "prog_print.h" + + +#define MAX_LOOP_NESTING 50 + + +static GLboolean dbg = GL_FALSE; + +/* Returns the mask of channels read from the given srcreg in this instruction. + */ +static GLuint +get_src_arg_mask(const struct prog_instruction *inst, int arg) +{ + int writemask = inst->DstReg.WriteMask; + + if (inst->CondUpdate) + writemask = WRITEMASK_XYZW; + + switch (inst->Opcode) { + case OPCODE_MOV: + case OPCODE_ABS: + case OPCODE_ADD: + case OPCODE_MUL: + case OPCODE_SUB: + return writemask; + case OPCODE_RCP: + case OPCODE_SIN: + case OPCODE_COS: + case OPCODE_RSQ: + case OPCODE_POW: + case OPCODE_EX2: + return WRITEMASK_X; + case OPCODE_DP2: + return WRITEMASK_XY; + case OPCODE_DP3: + case OPCODE_XPD: + return WRITEMASK_XYZ; + default: + return WRITEMASK_XYZW; + } +} + +/** + * In 'prog' remove instruction[i] if removeFlags[i] == TRUE. + * \return number of instructions removed + */ +static GLuint +remove_instructions(struct gl_program *prog, const GLboolean *removeFlags) +{ + GLint i, removeEnd = 0, removeCount = 0; + GLuint totalRemoved = 0; + + /* go backward */ + for (i = prog->NumInstructions - 1; i >= 0; i--) { + if (removeFlags[i]) { + totalRemoved++; + if (removeCount == 0) { + /* begin a run of instructions to remove */ + removeEnd = i; + removeCount = 1; + } + else { + /* extend the run of instructions to remove */ + removeCount++; + } + } + else { + /* don't remove this instruction, but check if the preceeding + * instructions are to be removed. + */ + if (removeCount > 0) { + GLint removeStart = removeEnd - removeCount + 1; + _mesa_delete_instructions(prog, removeStart, removeCount); + removeStart = removeCount = 0; /* reset removal info */ + } + } + } + /* Finish removing if the first instruction was to be removed. */ + if (removeCount > 0) { + GLint removeStart = removeEnd - removeCount + 1; + _mesa_delete_instructions(prog, removeStart, removeCount); + } + return totalRemoved; +} + + +/** + * Remap register indexes according to map. + * \param prog the program to search/replace + * \param file the type of register file to search/replace + * \param map maps old register indexes to new indexes + */ +static void +replace_regs(struct gl_program *prog, gl_register_file file, const GLint map[]) +{ + GLuint i; + + for (i = 0; i < prog->NumInstructions; i++) { + struct prog_instruction *inst = prog->Instructions + i; + const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode); + GLuint j; + for (j = 0; j < numSrc; j++) { + if (inst->SrcReg[j].File == file) { + GLuint index = inst->SrcReg[j].Index; + ASSERT(map[index] >= 0); + inst->SrcReg[j].Index = map[index]; + } + } + if (inst->DstReg.File == file) { + const GLuint index = inst->DstReg.Index; + ASSERT(map[index] >= 0); + inst->DstReg.Index = map[index]; + } + } +} + + +/** + * Consolidate temporary registers to use low numbers. For example, if the + * shader only uses temps 4, 5, 8, replace them with 0, 1, 2. + */ +static void +_mesa_consolidate_registers(struct gl_program *prog) +{ + GLboolean tempUsed[MAX_PROGRAM_TEMPS]; + GLint tempMap[MAX_PROGRAM_TEMPS]; + GLuint tempMax = 0, i; + + if (dbg) { + printf("Optimize: Begin register consolidation\n"); + } + + memset(tempUsed, 0, sizeof(tempUsed)); + + for (i = 0; i < MAX_PROGRAM_TEMPS; i++) { + tempMap[i] = -1; + } + + /* set tempUsed[i] if temporary [i] is referenced */ + for (i = 0; i < prog->NumInstructions; i++) { + const struct prog_instruction *inst = prog->Instructions + i; + const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode); + GLuint j; + for (j = 0; j < numSrc; j++) { + if (inst->SrcReg[j].File == PROGRAM_TEMPORARY) { + const GLuint index = inst->SrcReg[j].Index; + ASSERT(index < MAX_PROGRAM_TEMPS); + tempUsed[index] = GL_TRUE; + tempMax = MAX2(tempMax, index); + break; + } + } + if (inst->DstReg.File == PROGRAM_TEMPORARY) { + const GLuint index = inst->DstReg.Index; + ASSERT(index < MAX_PROGRAM_TEMPS); + tempUsed[index] = GL_TRUE; + tempMax = MAX2(tempMax, index); + } + } + + /* allocate a new index for each temp that's used */ + { + GLuint freeTemp = 0; + for (i = 0; i <= tempMax; i++) { + if (tempUsed[i]) { + tempMap[i] = freeTemp++; + /*printf("replace %u with %u\n", i, tempMap[i]);*/ + } + } + if (freeTemp == tempMax + 1) { + /* no consolidation possible */ + return; + } + if (dbg) { + printf("Replace regs 0..%u with 0..%u\n", tempMax, freeTemp-1); + } + } + + replace_regs(prog, PROGRAM_TEMPORARY, tempMap); + + if (dbg) { + printf("Optimize: End register consolidation\n"); + } +} + + +/** + * Remove dead instructions from the given program. + * This is very primitive for now. Basically look for temp registers + * that are written to but never read. Remove any instructions that + * write to such registers. Be careful with condition code setters. + */ +static void +_mesa_remove_dead_code(struct gl_program *prog) +{ + GLboolean tempRead[MAX_PROGRAM_TEMPS][4]; + GLboolean *removeInst; /* per-instruction removal flag */ + GLuint i, rem = 0, comp; + + memset(tempRead, 0, sizeof(tempRead)); + + if (dbg) { + printf("Optimize: Begin dead code removal\n"); + /*_mesa_print_program(prog);*/ + } + + removeInst = (GLboolean *) + calloc(1, prog->NumInstructions * sizeof(GLboolean)); + + /* Determine which temps are read and written */ + for (i = 0; i < prog->NumInstructions; i++) { + const struct prog_instruction *inst = prog->Instructions + i; + const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode); + GLuint j; + + /* check src regs */ + for (j = 0; j < numSrc; j++) { + if (inst->SrcReg[j].File == PROGRAM_TEMPORARY) { + const GLuint index = inst->SrcReg[j].Index; + GLuint read_mask; + ASSERT(index < MAX_PROGRAM_TEMPS); + read_mask = get_src_arg_mask(inst, j); + + if (inst->SrcReg[j].RelAddr) { + if (dbg) + printf("abort remove dead code (indirect temp)\n"); + goto done; + } + + for (comp = 0; comp < 4; comp++) { + GLuint swz = (inst->SrcReg[j].Swizzle >> (3 * comp)) & 0x7; + + if ((read_mask & (1 << comp)) == 0) + continue; + + switch (swz) { + case SWIZZLE_X: + tempRead[index][0] = GL_TRUE; + break; + case SWIZZLE_Y: + tempRead[index][1] = GL_TRUE; + break; + case SWIZZLE_Z: + tempRead[index][2] = GL_TRUE; + break; + case SWIZZLE_W: + tempRead[index][3] = GL_TRUE; + break; + } + } + } + } + + /* check dst reg */ + if (inst->DstReg.File == PROGRAM_TEMPORARY) { + const GLuint index = inst->DstReg.Index; + ASSERT(index < MAX_PROGRAM_TEMPS); + + if (inst->DstReg.RelAddr) { + if (dbg) + printf("abort remove dead code (indirect temp)\n"); + goto done; + } + + if (inst->CondUpdate) { + /* If we're writing to this register and setting condition + * codes we cannot remove the instruction. Prevent removal + * by setting the 'read' flag. + */ + tempRead[index][0] = GL_TRUE; + tempRead[index][1] = GL_TRUE; + tempRead[index][2] = GL_TRUE; + tempRead[index][3] = GL_TRUE; + } + } + } + + /* find instructions that write to dead registers, flag for removal */ + for (i = 0; i < prog->NumInstructions; i++) { + struct prog_instruction *inst = prog->Instructions + i; + const GLuint numDst = _mesa_num_inst_dst_regs(inst->Opcode); + + if (numDst != 0 && inst->DstReg.File == PROGRAM_TEMPORARY) { + GLint chan, index = inst->DstReg.Index; + + for (chan = 0; chan < 4; chan++) { + if (!tempRead[index][chan] && + inst->DstReg.WriteMask & (1 << chan)) { + if (dbg) { + printf("Remove writemask on %u.%c\n", i, + chan == 3 ? 'w' : 'x' + chan); + } + inst->DstReg.WriteMask &= ~(1 << chan); + rem++; + } + } + + if (inst->DstReg.WriteMask == 0) { + /* If we cleared all writes, the instruction can be removed. */ + if (dbg) + printf("Remove instruction %u: \n", i); + removeInst[i] = GL_TRUE; + } + } + } + + /* now remove the instructions which aren't needed */ + rem = remove_instructions(prog, removeInst); + + if (dbg) { + printf("Optimize: End dead code removal.\n"); + printf(" %u channel writes removed\n", rem); + printf(" %u instructions removed\n", rem); + /*_mesa_print_program(prog);*/ + } + +done: + free(removeInst); +} + + +enum temp_use +{ + READ, + WRITE, + FLOW, + END +}; + +/** + * Scan forward in program from 'start' for the next occurance of TEMP[index]. + * Return READ, WRITE, FLOW or END to indicate the next usage or an indicator + * that we can't look further. + */ +static enum temp_use +find_next_temp_use(const struct gl_program *prog, GLuint start, GLuint index) +{ + GLuint i; + + for (i = start; i < prog->NumInstructions; i++) { + const struct prog_instruction *inst = prog->Instructions + i; + switch (inst->Opcode) { + case OPCODE_BGNLOOP: + case OPCODE_ENDLOOP: + case OPCODE_BGNSUB: + case OPCODE_ENDSUB: + return FLOW; + default: + { + const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode); + GLuint j; + for (j = 0; j < numSrc; j++) { + if (inst->SrcReg[j].File == PROGRAM_TEMPORARY && + inst->SrcReg[j].Index == index) + return READ; + } + if (inst->DstReg.File == PROGRAM_TEMPORARY && + inst->DstReg.Index == index) + return WRITE; + } + } + } + + return END; +} + +static GLboolean _mesa_is_flow_control_opcode(enum prog_opcode opcode) +{ + switch (opcode) { + case OPCODE_BGNLOOP: + case OPCODE_BGNSUB: + case OPCODE_BRA: + case OPCODE_CAL: + case OPCODE_CONT: + case OPCODE_IF: + case OPCODE_ELSE: + case OPCODE_END: + case OPCODE_ENDIF: + case OPCODE_ENDLOOP: + case OPCODE_ENDSUB: + case OPCODE_RET: + return GL_TRUE; + default: + return GL_FALSE; + } +} + +/** + * Try to remove use of extraneous MOV instructions, to free them up for dead + * code removal. + */ +static void +_mesa_remove_extra_move_use(struct gl_program *prog) +{ + GLuint i, j; + + if (dbg) { + printf("Optimize: Begin remove extra move use\n"); + _mesa_print_program(prog); + } + + /* + * Look for sequences such as this: + * MOV tmpX, arg0; + * ... + * FOO tmpY, tmpX, arg1; + * and convert into: + * MOV tmpX, arg0; + * ... + * FOO tmpY, arg0, arg1; + */ + + for (i = 0; i + 1 < prog->NumInstructions; i++) { + const struct prog_instruction *mov = prog->Instructions + i; + + if (mov->Opcode != OPCODE_MOV || + mov->DstReg.File != PROGRAM_TEMPORARY || + mov->DstReg.RelAddr || + mov->DstReg.CondMask != COND_TR || + mov->SaturateMode != SATURATE_OFF || + mov->SrcReg[0].RelAddr) + continue; + + /* Walk through remaining instructions until the or src reg gets + * rewritten or we get into some flow-control, eliminating the use of + * this MOV. + */ + for (j = i + 1; j < prog->NumInstructions; j++) { + struct prog_instruction *inst2 = prog->Instructions + j; + GLuint arg; + + if (_mesa_is_flow_control_opcode(inst2->Opcode)) + break; + + /* First rewrite this instruction's args if appropriate. */ + for (arg = 0; arg < _mesa_num_inst_src_regs(inst2->Opcode); arg++) { + int comp; + int read_mask = get_src_arg_mask(inst2, arg); + + if (inst2->SrcReg[arg].File != mov->DstReg.File || + inst2->SrcReg[arg].Index != mov->DstReg.Index || + inst2->SrcReg[arg].RelAddr || + inst2->SrcReg[arg].Abs) + continue; + + /* Check that all the sources for this arg of inst2 come from inst1 + * or constants. + */ + for (comp = 0; comp < 4; comp++) { + int src_swz = GET_SWZ(inst2->SrcReg[arg].Swizzle, comp); + + /* If the MOV didn't write that channel, can't use it. */ + if ((read_mask & (1 << comp)) && + src_swz <= SWIZZLE_W && + (mov->DstReg.WriteMask & (1 << src_swz)) == 0) + break; + } + if (comp != 4) + continue; + + /* Adjust the swizzles of inst2 to point at MOV's source */ + for (comp = 0; comp < 4; comp++) { + int inst2_swz = GET_SWZ(inst2->SrcReg[arg].Swizzle, comp); + + if (inst2_swz <= SWIZZLE_W) { + GLuint s = GET_SWZ(mov->SrcReg[0].Swizzle, inst2_swz); + inst2->SrcReg[arg].Swizzle &= ~(7 << (3 * comp)); + inst2->SrcReg[arg].Swizzle |= s << (3 * comp); + inst2->SrcReg[arg].Negate ^= (((mov->SrcReg[0].Negate >> + inst2_swz) & 0x1) << comp); + } + } + inst2->SrcReg[arg].File = mov->SrcReg[0].File; + inst2->SrcReg[arg].Index = mov->SrcReg[0].Index; + } + + /* If this instruction overwrote part of the move, our time is up. */ + if ((inst2->DstReg.File == mov->DstReg.File && + (inst2->DstReg.RelAddr || + inst2->DstReg.Index == mov->DstReg.Index)) || + (inst2->DstReg.File == mov->SrcReg[0].File && + (inst2->DstReg.RelAddr || + inst2->DstReg.Index == mov->SrcReg[0].Index))) + break; + } + } + + if (dbg) { + printf("Optimize: End remove extra move use.\n"); + /*_mesa_print_program(prog);*/ + } +} + +/** + * Try to remove extraneous MOV instructions from the given program. + */ +static void +_mesa_remove_extra_moves(struct gl_program *prog) +{ + GLboolean *removeInst; /* per-instruction removal flag */ + GLuint i, rem, loopNesting = 0, subroutineNesting = 0; + + if (dbg) { + printf("Optimize: Begin remove extra moves\n"); + _mesa_print_program(prog); + } + + removeInst = (GLboolean *) + calloc(1, prog->NumInstructions * sizeof(GLboolean)); + + /* + * Look for sequences such as this: + * FOO tmpX, arg0, arg1; + * MOV tmpY, tmpX; + * and convert into: + * FOO tmpY, arg0, arg1; + */ + + for (i = 0; i < prog->NumInstructions; i++) { + const struct prog_instruction *inst = prog->Instructions + i; + + switch (inst->Opcode) { + case OPCODE_BGNLOOP: + loopNesting++; + break; + case OPCODE_ENDLOOP: + loopNesting--; + break; + case OPCODE_BGNSUB: + subroutineNesting++; + break; + case OPCODE_ENDSUB: + subroutineNesting--; + break; + case OPCODE_MOV: + if (i > 0 && + loopNesting == 0 && + subroutineNesting == 0 && + inst->SrcReg[0].File == PROGRAM_TEMPORARY && + inst->SrcReg[0].Swizzle == SWIZZLE_XYZW) { + /* see if this MOV can be removed */ + const GLuint tempIndex = inst->SrcReg[0].Index; + struct prog_instruction *prevInst; + GLuint prevI; + + /* get pointer to previous instruction */ + prevI = i - 1; + while (prevI > 0 && removeInst[prevI]) + prevI--; + prevInst = prog->Instructions + prevI; + + if (prevInst->DstReg.File == PROGRAM_TEMPORARY && + prevInst->DstReg.Index == tempIndex && + prevInst->DstReg.WriteMask == WRITEMASK_XYZW) { + + enum temp_use next_use = + find_next_temp_use(prog, i + 1, tempIndex); + + if (next_use == WRITE || next_use == END) { + /* OK, we can safely remove this MOV instruction. + * Transform: + * prevI: FOO tempIndex, x, y; + * i: MOV z, tempIndex; + * Into: + * prevI: FOO z, x, y; + */ + + /* patch up prev inst */ + prevInst->DstReg.File = inst->DstReg.File; + prevInst->DstReg.Index = inst->DstReg.Index; + + /* flag this instruction for removal */ + removeInst[i] = GL_TRUE; + + if (dbg) { + printf("Remove MOV at %u\n", i); + printf("new prev inst %u: ", prevI); + _mesa_print_instruction(prevInst); + } + } + } + } + break; + default: + ; /* nothing */ + } + } + + /* now remove the instructions which aren't needed */ + rem = remove_instructions(prog, removeInst); + + free(removeInst); + + if (dbg) { + printf("Optimize: End remove extra moves. %u instructions removed\n", rem); + /*_mesa_print_program(prog);*/ + } +} + + +/** A live register interval */ +struct interval +{ + GLuint Reg; /** The temporary register index */ + GLuint Start, End; /** Start/end instruction numbers */ +}; + + +/** A list of register intervals */ +struct interval_list +{ + GLuint Num; + struct interval Intervals[MAX_PROGRAM_TEMPS]; +}; + + +static void +append_interval(struct interval_list *list, const struct interval *inv) +{ + list->Intervals[list->Num++] = *inv; +} + + +/** Insert interval inv into list, sorted by interval end */ +static void +insert_interval_by_end(struct interval_list *list, const struct interval *inv) +{ + /* XXX we could do a binary search insertion here since list is sorted */ + GLint i = list->Num - 1; + while (i >= 0 && list->Intervals[i].End > inv->End) { + list->Intervals[i + 1] = list->Intervals[i]; + i--; + } + list->Intervals[i + 1] = *inv; + list->Num++; + +#ifdef DEBUG + { + GLuint i; + for (i = 0; i + 1 < list->Num; i++) { + ASSERT(list->Intervals[i].End <= list->Intervals[i + 1].End); + } + } +#endif +} + + +/** Remove the given interval from the interval list */ +static void +remove_interval(struct interval_list *list, const struct interval *inv) +{ + /* XXX we could binary search since list is sorted */ + GLuint k; + for (k = 0; k < list->Num; k++) { + if (list->Intervals[k].Reg == inv->Reg) { + /* found, remove it */ + ASSERT(list->Intervals[k].Start == inv->Start); + ASSERT(list->Intervals[k].End == inv->End); + while (k < list->Num - 1) { + list->Intervals[k] = list->Intervals[k + 1]; + k++; + } + list->Num--; + return; + } + } +} + + +/** called by qsort() */ +static int +compare_start(const void *a, const void *b) +{ + const struct interval *ia = (const struct interval *) a; + const struct interval *ib = (const struct interval *) b; + if (ia->Start < ib->Start) + return -1; + else if (ia->Start > ib->Start) + return +1; + else + return 0; +} + +/** sort the interval list according to interval starts */ +static void +sort_interval_list_by_start(struct interval_list *list) +{ + qsort(list->Intervals, list->Num, sizeof(struct interval), compare_start); +#ifdef DEBUG + { + GLuint i; + for (i = 0; i + 1 < list->Num; i++) { + ASSERT(list->Intervals[i].Start <= list->Intervals[i + 1].Start); + } + } +#endif +} + +struct loop_info +{ + GLuint Start, End; /**< Start, end instructions of loop */ +}; + +/** + * Update the intermediate interval info for register 'index' and + * instruction 'ic'. + */ +static void +update_interval(GLint intBegin[], GLint intEnd[], + struct loop_info *loopStack, GLuint loopStackDepth, + GLuint index, GLuint ic) +{ + int i; + + /* If the register is used in a loop, extend its lifetime through the end + * of the outermost loop that doesn't contain its definition. + */ + for (i = 0; i < loopStackDepth; i++) { + if (intBegin[index] < loopStack[i].Start) { + ic = loopStack[i].End; + break; + } + } + + ASSERT(index < MAX_PROGRAM_TEMPS); + if (intBegin[index] == -1) { + ASSERT(intEnd[index] == -1); + intBegin[index] = intEnd[index] = ic; + } + else { + intEnd[index] = ic; + } +} + + +/** + * Find first/last instruction that references each temporary register. + */ +GLboolean +_mesa_find_temp_intervals(const struct prog_instruction *instructions, + GLuint numInstructions, + GLint intBegin[MAX_PROGRAM_TEMPS], + GLint intEnd[MAX_PROGRAM_TEMPS]) +{ + struct loop_info loopStack[MAX_LOOP_NESTING]; + GLuint loopStackDepth = 0; + GLuint i; + + for (i = 0; i < MAX_PROGRAM_TEMPS; i++){ + intBegin[i] = intEnd[i] = -1; + } + + /* Scan instructions looking for temporary registers */ + for (i = 0; i < numInstructions; i++) { + const struct prog_instruction *inst = instructions + i; + if (inst->Opcode == OPCODE_BGNLOOP) { + loopStack[loopStackDepth].Start = i; + loopStack[loopStackDepth].End = inst->BranchTarget; + loopStackDepth++; + } + else if (inst->Opcode == OPCODE_ENDLOOP) { + loopStackDepth--; + } + else if (inst->Opcode == OPCODE_CAL) { + return GL_FALSE; + } + else { + const GLuint numSrc = 3;/*_mesa_num_inst_src_regs(inst->Opcode);*/ + GLuint j; + for (j = 0; j < numSrc; j++) { + if (inst->SrcReg[j].File == PROGRAM_TEMPORARY) { + const GLuint index = inst->SrcReg[j].Index; + if (inst->SrcReg[j].RelAddr) + return GL_FALSE; + update_interval(intBegin, intEnd, loopStack, loopStackDepth, + index, i); + } + } + if (inst->DstReg.File == PROGRAM_TEMPORARY) { + const GLuint index = inst->DstReg.Index; + if (inst->DstReg.RelAddr) + return GL_FALSE; + update_interval(intBegin, intEnd, loopStack, loopStackDepth, + index, i); + } + } + } + + return GL_TRUE; +} + + +/** + * Find the live intervals for each temporary register in the program. + * For register R, the interval [A,B] indicates that R is referenced + * from instruction A through instruction B. + * Special consideration is needed for loops and subroutines. + * \return GL_TRUE if success, GL_FALSE if we cannot proceed for some reason + */ +static GLboolean +find_live_intervals(struct gl_program *prog, + struct interval_list *liveIntervals) +{ + GLint intBegin[MAX_PROGRAM_TEMPS], intEnd[MAX_PROGRAM_TEMPS]; + GLuint i; + + /* + * Note: we'll return GL_FALSE below if we find relative indexing + * into the TEMP register file. We can't handle that yet. + * We also give up on subroutines for now. + */ + + if (dbg) { + printf("Optimize: Begin find intervals\n"); + } + + /* build intermediate arrays */ + if (!_mesa_find_temp_intervals(prog->Instructions, prog->NumInstructions, + intBegin, intEnd)) + return GL_FALSE; + + /* Build live intervals list from intermediate arrays */ + liveIntervals->Num = 0; + for (i = 0; i < MAX_PROGRAM_TEMPS; i++) { + if (intBegin[i] >= 0) { + struct interval inv; + inv.Reg = i; + inv.Start = intBegin[i]; + inv.End = intEnd[i]; + append_interval(liveIntervals, &inv); + } + } + + /* Sort the list according to interval starts */ + sort_interval_list_by_start(liveIntervals); + + if (dbg) { + /* print interval info */ + for (i = 0; i < liveIntervals->Num; i++) { + const struct interval *inv = liveIntervals->Intervals + i; + printf("Reg[%d] live [%d, %d]:", + inv->Reg, inv->Start, inv->End); + if (1) { + GLuint j; + for (j = 0; j < inv->Start; j++) + printf(" "); + for (j = inv->Start; j <= inv->End; j++) + printf("x"); + } + printf("\n"); + } + } + + return GL_TRUE; +} + + +/** Scan the array of used register flags to find free entry */ +static GLint +alloc_register(GLboolean usedRegs[MAX_PROGRAM_TEMPS]) +{ + GLuint k; + for (k = 0; k < MAX_PROGRAM_TEMPS; k++) { + if (!usedRegs[k]) { + usedRegs[k] = GL_TRUE; + return k; + } + } + return -1; +} + + +/** + * This function implements "Linear Scan Register Allocation" to reduce + * the number of temporary registers used by the program. + * + * We compute the "live interval" for all temporary registers then + * examine the overlap of the intervals to allocate new registers. + * Basically, if two intervals do not overlap, they can use the same register. + */ +static void +_mesa_reallocate_registers(struct gl_program *prog) +{ + struct interval_list liveIntervals; + GLint registerMap[MAX_PROGRAM_TEMPS]; + GLboolean usedRegs[MAX_PROGRAM_TEMPS]; + GLuint i; + GLint maxTemp = -1; + + if (dbg) { + printf("Optimize: Begin live-interval register reallocation\n"); + _mesa_print_program(prog); + } + + for (i = 0; i < MAX_PROGRAM_TEMPS; i++){ + registerMap[i] = -1; + usedRegs[i] = GL_FALSE; + } + + if (!find_live_intervals(prog, &liveIntervals)) { + if (dbg) + printf("Aborting register reallocation\n"); + return; + } + + { + struct interval_list activeIntervals; + activeIntervals.Num = 0; + + /* loop over live intervals, allocating a new register for each */ + for (i = 0; i < liveIntervals.Num; i++) { + const struct interval *live = liveIntervals.Intervals + i; + + if (dbg) + printf("Consider register %u\n", live->Reg); + + /* Expire old intervals. Intervals which have ended with respect + * to the live interval can have their remapped registers freed. + */ + { + GLint j; + for (j = 0; j < (GLint) activeIntervals.Num; j++) { + const struct interval *inv = activeIntervals.Intervals + j; + if (inv->End >= live->Start) { + /* Stop now. Since the activeInterval list is sorted + * we know we don't have to go further. + */ + break; + } + else { + /* Interval 'inv' has expired */ + const GLint regNew = registerMap[inv->Reg]; + ASSERT(regNew >= 0); + + if (dbg) + printf(" expire interval for reg %u\n", inv->Reg); + + /* remove interval j from active list */ + remove_interval(&activeIntervals, inv); + j--; /* counter-act j++ in for-loop above */ + + /* return register regNew to the free pool */ + if (dbg) + printf(" free reg %d\n", regNew); + ASSERT(usedRegs[regNew] == GL_TRUE); + usedRegs[regNew] = GL_FALSE; + } + } + } + + /* find a free register for this live interval */ + { + const GLint k = alloc_register(usedRegs); + if (k < 0) { + /* out of registers, give up */ + return; + } + registerMap[live->Reg] = k; + maxTemp = MAX2(maxTemp, k); + if (dbg) + printf(" remap register %u -> %d\n", live->Reg, k); + } + + /* Insert this live interval into the active list which is sorted + * by increasing end points. + */ + insert_interval_by_end(&activeIntervals, live); + } + } + + if (maxTemp + 1 < (GLint) liveIntervals.Num) { + /* OK, we've reduced the number of registers needed. + * Scan the program and replace all the old temporary register + * indexes with the new indexes. + */ + replace_regs(prog, PROGRAM_TEMPORARY, registerMap); + + prog->NumTemporaries = maxTemp + 1; + } + + if (dbg) { + printf("Optimize: End live-interval register reallocation\n"); + printf("Num temp regs before: %u after: %u\n", + liveIntervals.Num, maxTemp + 1); + _mesa_print_program(prog); + } +} + + +/** + * Apply optimizations to the given program to eliminate unnecessary + * instructions, temp regs, etc. + */ +void +_mesa_optimize_program(GLcontext *ctx, struct gl_program *program) +{ + _mesa_remove_extra_move_use(program); + + if (1) + _mesa_remove_dead_code(program); + + if (0) /* not tested much yet */ + _mesa_remove_extra_moves(program); + + if (0) + _mesa_consolidate_registers(program); + else + _mesa_reallocate_registers(program); +} |