/*
 * Copyright 2009 Nicolai Haehnle.
 * SPDX-License-Identifier: MIT
 */

#include "radeon_program_pair.h"

#include "radeon_compiler.h"
#include "radeon_compiler_util.h"

#include "util/compiler.h"

/**
 * Finally rewrite ADD, MOV, MUL as the appropriate native instruction
 * and reverse the order of arguments for CMP.
 */
static void
final_rewrite(struct rc_sub_instruction *inst)
{
   struct rc_src_register tmp;

   switch (inst->Opcode) {
   case RC_OPCODE_ADD:
      inst->SrcReg[2] = inst->SrcReg[1];
      inst->SrcReg[1].File = RC_FILE_NONE;
      inst->SrcReg[1].Swizzle = RC_SWIZZLE_1111;
      inst->SrcReg[1].Negate = RC_MASK_NONE;
      inst->Opcode = RC_OPCODE_MAD;
      break;
   case RC_OPCODE_CMP:
      tmp = inst->SrcReg[2];
      inst->SrcReg[2] = inst->SrcReg[0];
      inst->SrcReg[0] = tmp;
      break;
   case RC_OPCODE_MOV:
      inst->SrcReg[1] = inst->SrcReg[0];
      inst->Opcode = RC_OPCODE_MAX;
      break;
   case RC_OPCODE_MUL:
      inst->SrcReg[2].File = RC_FILE_NONE;
      inst->SrcReg[2].Swizzle = RC_SWIZZLE_0000;
      inst->Opcode = RC_OPCODE_MAD;
      break;
   default:
      /* nothing to do */
      break;
   }
}

/**
 * ALU operations usually enable the output modifier, which in turn standardizes
 * NaN values and flushes denormal results to zero. A MOV instruction which
 * preserves the source bits is implemented by setting US_OMOD_DISABLED
 * for the instruction and using the MAX(src, src) instruction.
 * The output modifier cannot be disabled for a saturated MOV (MOV with clamping enabled).
 * RC_OMOD_DISABLE is only available on R5xx and is only valid with MIN/MAX/CMP/CND.
 */
static unsigned
translate_omod(struct r300_fragment_program_compiler *c, struct rc_sub_instruction *inst)
{
   if (c->Base.is_r500 && inst->Omod == RC_OMOD_MUL_1 && !inst->SaturateMode &&
       (inst->Opcode == RC_OPCODE_MAX || inst->Opcode == RC_OPCODE_MIN ||
        inst->Opcode == RC_OPCODE_CMP || inst->Opcode == RC_OPCODE_CND))
      return RC_OMOD_DISABLE;
   return inst->Omod;
}

/**
 * Classify an instruction according to which ALUs etc. it needs
 */
static void
classify_instruction(struct rc_sub_instruction *inst, int *needrgb, int *needalpha,
                     int *istranscendent)
{
   *needrgb = (inst->DstReg.WriteMask & RC_MASK_XYZ) ? 1 : 0;
   *needalpha = (inst->DstReg.WriteMask & RC_MASK_W) ? 1 : 0;
   *istranscendent = 0;

   if (inst->WriteALUResult == RC_ALURESULT_X)
      *needrgb = 1;
   else if (inst->WriteALUResult == RC_ALURESULT_W)
      *needalpha = 1;

   switch (inst->Opcode) {
   case RC_OPCODE_ADD:
   case RC_OPCODE_CMP:
   case RC_OPCODE_CND:
   case RC_OPCODE_DDX:
   case RC_OPCODE_DDY:
   case RC_OPCODE_FRC:
   case RC_OPCODE_MAD:
   case RC_OPCODE_MAX:
   case RC_OPCODE_MIN:
   case RC_OPCODE_MOV:
   case RC_OPCODE_MUL: break;
   case RC_OPCODE_COS:
   case RC_OPCODE_EX2:
   case RC_OPCODE_LG2:
   case RC_OPCODE_RCP:
   case RC_OPCODE_RSQ:
   case RC_OPCODE_SIN:
      *istranscendent = 1;
      *needalpha = 1;
      break;
   case RC_OPCODE_DP4: *needalpha = 1; FALLTHROUGH;
   case RC_OPCODE_DP3: *needrgb = 1; break;
   default: break;
   }
}

static void
src_uses(struct rc_src_register src, unsigned int *rgb, unsigned int *alpha)
{
   int j;
   for (j = 0; j < 4; ++j) {
      unsigned int swz = GET_SWZ(src.Swizzle, j);
      if (swz < 3)
         *rgb = 1;
      else if (swz < 4)
         *alpha = 1;
   }
}

/**
 * Fill the given ALU instruction's opcodes and source operands into the given pair,
 * if possible.
 */
static void
set_pair_instruction(struct r300_fragment_program_compiler *c, struct rc_pair_instruction *pair,
                     struct rc_sub_instruction *inst)
{
   int needrgb, needalpha, istranscendent;
   const struct rc_opcode_info *opcode;
   int i;

   memset(pair, 0, sizeof(struct rc_pair_instruction));

   classify_instruction(inst, &needrgb, &needalpha, &istranscendent);

   if (needrgb) {
      if (istranscendent)
         pair->RGB.Opcode = RC_OPCODE_REPL_ALPHA;
      else
         pair->RGB.Opcode = inst->Opcode;
      if (inst->SaturateMode == RC_SATURATE_ZERO_ONE)
         pair->RGB.Saturate = 1;
   }
   if (needalpha) {
      pair->Alpha.Opcode = inst->Opcode;
      if (inst->SaturateMode == RC_SATURATE_ZERO_ONE)
         pair->Alpha.Saturate = 1;
   }

   opcode = rc_get_opcode_info(inst->Opcode);

   /* Presubtract handling:
    * We need to make sure that the values used by the presubtract
    * operation end up in src0 or src1. */
   if (inst->PreSub.Opcode != RC_PRESUB_NONE) {
      /* rc_pair_alloc_source() will fill in data for
       * pair->{RGB,ALPHA}.Src[RC_PAIR_PRESUB_SRC] */
      int j;
      for (j = 0; j < 3; j++) {
         int src_regs;
         if (inst->SrcReg[j].File != RC_FILE_PRESUB)
            continue;

         src_regs = rc_presubtract_src_reg_count(inst->PreSub.Opcode);
         for (i = 0; i < src_regs; i++) {
            unsigned int rgb = 0;
            unsigned int alpha = 0;
            src_uses(inst->SrcReg[j], &rgb, &alpha);
            if (rgb) {
               pair->RGB.Src[i].File = inst->PreSub.SrcReg[i].File;
               pair->RGB.Src[i].Index = inst->PreSub.SrcReg[i].Index;
               pair->RGB.Src[i].Used = 1;
            }
            if (alpha) {
               pair->Alpha.Src[i].File = inst->PreSub.SrcReg[i].File;
               pair->Alpha.Src[i].Index = inst->PreSub.SrcReg[i].Index;
               pair->Alpha.Src[i].Used = 1;
            }
         }
      }
   }

   for (i = 0; i < opcode->NumSrcRegs; ++i) {
      int source;
      if (needrgb && !istranscendent) {
         unsigned int srcrgb = 0;
         unsigned int srcalpha = 0;
         unsigned int srcmask = 0;
         int j;
         /* We don't care about the alpha channel here.  We only
          * want the part of the swizzle that writes to rgb,
          * since we are creating an rgb instruction. */
         for (j = 0; j < 3; ++j) {
            unsigned int swz = GET_SWZ(inst->SrcReg[i].Swizzle, j);

            if (swz < RC_SWIZZLE_W)
               srcrgb = 1;
            else if (swz == RC_SWIZZLE_W)
               srcalpha = 1;

            /* We check for ZERO here as well because otherwise the zero
             * sign (which doesn't matter and we already ignore it previously
             * when checking for valid swizzle) could mess up the final negate sign.
             * Example problematic pattern where this would be produced is:
             *   CONST[1] FLT32 {   0.0000,     0.0000,    -4.0000,     0.0000}
             *   ADD temp[0].xyz, const[0].xyz_, -const[1].z00_;
             *
             * after inline literals would become:
             *   ADD temp[0].xyz, const[0].xyz_, 4.000000 (0x48).w-0-0-_;
             *
             * and after pair translate:
             *   src0.xyz = const[0], src0.w = 4.000000 (0x48)
             *   MAD temp[0].xyz, src0.xyz, src0.111, src0.w00
             *
             * Without the zero check there would be -src0.w00.
             */
            if (swz < RC_SWIZZLE_UNUSED && swz != RC_SWIZZLE_ZERO)
               srcmask |= 1 << j;
         }
         source = rc_pair_alloc_source(pair, srcrgb, srcalpha, inst->SrcReg[i].File,
                                       inst->SrcReg[i].Index);
         if (source < 0) {
            rc_error(&c->Base, "Failed to translate rgb instruction");
            return;
         }
         pair->RGB.Arg[i].Source = source;
         pair->RGB.Arg[i].Swizzle = rc_init_swizzle(inst->SrcReg[i].Swizzle, 3);
         pair->RGB.Arg[i].Abs = inst->SrcReg[i].Abs;
         pair->RGB.Arg[i].Negate =
            !!(srcmask & inst->SrcReg[i].Negate & (RC_MASK_X | RC_MASK_Y | RC_MASK_Z));
      }
      if (needalpha) {
         unsigned int srcrgb = 0;
         unsigned int srcalpha = 0;
         unsigned int swz;
         if (istranscendent) {
            swz = rc_get_scalar_src_swz(inst->SrcReg[i].Swizzle);
         } else {
            swz = GET_SWZ(inst->SrcReg[i].Swizzle, 3);
         }

         if (swz < 3)
            srcrgb = 1;
         else if (swz < 4)
            srcalpha = 1;
         source = rc_pair_alloc_source(pair, srcrgb, srcalpha, inst->SrcReg[i].File,
                                       inst->SrcReg[i].Index);
         if (source < 0) {
            rc_error(&c->Base, "Failed to translate alpha instruction");
            return;
         }
         pair->Alpha.Arg[i].Source = source;
         pair->Alpha.Arg[i].Swizzle = rc_init_swizzle(swz, 1);
         pair->Alpha.Arg[i].Abs = inst->SrcReg[i].Abs;

         if (istranscendent) {
            pair->Alpha.Arg[i].Negate = !!(inst->SrcReg[i].Negate & inst->DstReg.WriteMask);
         } else {
            pair->Alpha.Arg[i].Negate = !!(inst->SrcReg[i].Negate & RC_MASK_W);
         }
      }
   }

   /* Destination handling */
   if (inst->DstReg.File == RC_FILE_OUTPUT) {
      if (inst->DstReg.Index == c->OutputDepth) {
         pair->Alpha.DepthWriteMask |= GET_BIT(inst->DstReg.WriteMask, 3);
      } else {
         for (i = 0; i < 4; i++) {
            if (inst->DstReg.Index == c->OutputColor[i]) {
               pair->RGB.Target = i;
               pair->Alpha.Target = i;
               pair->RGB.OutputWriteMask |= inst->DstReg.WriteMask & RC_MASK_XYZ;
               pair->Alpha.OutputWriteMask |= GET_BIT(inst->DstReg.WriteMask, 3);
               break;
            }
         }
      }
   } else {
      if (needrgb) {
         pair->RGB.DestIndex = inst->DstReg.Index;
         pair->RGB.WriteMask |= inst->DstReg.WriteMask & RC_MASK_XYZ;
      }

      if (needalpha) {
         pair->Alpha.WriteMask |= (GET_BIT(inst->DstReg.WriteMask, 3) << 3);
         if (pair->Alpha.WriteMask) {
            pair->Alpha.DestIndex = inst->DstReg.Index;
         }
      }
   }

   if (needrgb) {
      pair->RGB.Omod = translate_omod(c, inst);
   }
   if (needalpha) {
      pair->Alpha.Omod = translate_omod(c, inst);
   }

   if (inst->WriteALUResult) {
      pair->WriteALUResult = inst->WriteALUResult;
      pair->ALUResultCompare = inst->ALUResultCompare;
   }
}

static void
check_opcode_support(struct r300_fragment_program_compiler *c, struct rc_sub_instruction *inst)
{
   const struct rc_opcode_info *opcode = rc_get_opcode_info(inst->Opcode);

   if (opcode->HasDstReg) {
      if (inst->SaturateMode == RC_SATURATE_MINUS_PLUS_ONE) {
         rc_error(&c->Base, "Fragment program does not support signed Saturate");
         return;
      }
   }

   for (unsigned i = 0; i < opcode->NumSrcRegs; i++) {
      if (inst->SrcReg[i].RelAddr) {
         rc_error(&c->Base, "Fragment program does not support relative addressing "
                            " of source operands.");
         return;
      }
   }
}

/**
 * Translate all ALU instructions into corresponding pair instructions,
 * performing no other changes.
 */
void
rc_pair_translate(struct radeon_compiler *cc, void *user)
{
   struct r300_fragment_program_compiler *c = (struct r300_fragment_program_compiler *)cc;

   for (struct rc_instruction *inst = c->Base.Program.Instructions.Next;
        inst != &c->Base.Program.Instructions; inst = inst->Next) {
      const struct rc_opcode_info *opcode;
      struct rc_sub_instruction copy;

      if (inst->Type != RC_INSTRUCTION_NORMAL)
         continue;

      opcode = rc_get_opcode_info(inst->U.I.Opcode);

      if (opcode->HasTexture || opcode->IsFlowControl || opcode->Opcode == RC_OPCODE_KIL)
         continue;

      copy = inst->U.I;

      check_opcode_support(c, &copy);

      final_rewrite(&copy);
      inst->Type = RC_INSTRUCTION_PAIR;
      set_pair_instruction(c, &inst->U.P, &copy);
   }
}