Externals: rslc with gl_Layer in a pixel stage

The vendored rslc takes gl_Layer in a pixel stage, so the stereoscopic
pixel shaders, which read the layer the geometry stage chose, compile
for Vulkan and Direct3D.

Externals/libretro-common/gfx/shaders/rslc_dxbc.c

@@ -1329,7 +1329,7 @@ static bool dx_interface(struct dx_emit *e)
    const struct rslc_prog *pr = &e->c->prog;
    bool frag = e->c->stage == RSLC_STAGE_FRAGMENT;
    struct dx_packer pk;
-   uint32_t i, pass;
+   uint32_t i, layer, pass;
 
    if (e->c->stage == RSLC_STAGE_COMPUTE)
       return true;
@@ -1375,6 +1375,44 @@ static bool dx_interface(struct dx_emit *e)
          return false;
       dv->has_home = true;
    }
+   /* a pixel stage reading gl_Layer: the position, then the layer, where
+    * the geometry stage writes them, the position declared even when
+    * unread */
+   layer = 0;
+   for (i = 1; frag && i < pr->nvars; i++)
+   {
+      const struct rslc_var *v = pr->vars[i];
+      if (v->global && v->storage == RSLC_ST_BUILTIN && e->used[i]
+            && v->builtin == RSLC_BI_LAYER)
+         layer = i;
+   }
+   if (layer)
+   {
+      uint32_t reg;
+      uint8_t comp;
+      for (i = 1; i < pr->nvars; i++)
+      {
+         const struct rslc_var *v = pr->vars[i];
+         if (v->global && v->storage == RSLC_ST_BUILTIN && e->used[i]
+               && v->builtin == RSLC_BI_FRAGCOORD)
+            break;
+      }
+      if (!dx_pack(e, &pk, 4, 1, DX_GROUP_ALONE, &reg, &comp)
+            || !dx_sig_add(e, true, "SV_Position", 0, reg, 0, DX_SV_POSITION, DX_CT_FLOAT, 4,
+               DX_INTERP_NOPERSPECTIVE))
+         return false;
+      if (i < pr->nvars)
+      {
+         e->vars[i].home     = dx_place_of(DXO_INPUT, reg);
+         e->vars[i].has_home = true;
+      }
+      if (!dx_pack(e, &pk, 1, 1, DX_GROUP_ALONE, &reg, &comp)
+            || !dx_sig_add(e, true, "SV_RenderTargetArrayIndex", 0, reg, 0, DX_SV_RTINDEX,
+               DX_CT_UINT, 1, DX_INTERP_CONSTANT))
+         return false;
+      e->vars[layer].home     = dx_place_of(DXO_INPUT, reg);
+      e->vars[layer].has_home = true;
+   }
    for (i = 1; i < pr->nvars; i++)
    {
       const struct rslc_var *v = pr->vars[i];
@@ -1386,6 +1424,8 @@ static bool dx_interface(struct dx_emit *e)
       uint8_t comp;
       if (!v->global || v->storage != RSLC_ST_BUILTIN || !e->used[i])
          continue;
+      if (layer && (v->builtin == RSLC_BI_FRAGCOORD || v->builtin == RSLC_BI_LAYER))
+         continue;
       switch (v->builtin)
       {
          case RSLC_BI_FRAGCOORD:     name = "SV_Position"; sv = DX_SV_POSITION; n = 4; break;
@@ -1486,7 +1526,7 @@ static bool dx_interface(struct dx_emit *e)
       struct dx_var *dv = &e->vars[i];
       uint32_t n, reg;
       uint8_t comp;
-      if (!v->global || v->storage != RSLC_ST_BUILTIN || !e->used[i])
+      if (!v->global || v->storage != RSLC_ST_BUILTIN || !e->used[i] || v->dir != RSLC_DIR_OUT)
          continue;
       if (pass != (v->builtin == RSLC_BI_POSITION ? 0u : v->builtin == RSLC_BI_LAYER ? 1u : 2u))
          continue;
@@ -4693,8 +4733,8 @@ static bool dx_decls(struct dx_emit *e)
       }
       if (frag)
       {
-         op = s->sv ? (s->sv == DX_SV_POSITION ? DX_DCL_INPUT_PS_SIV : DX_DCL_INPUT_PS_SGV)
-            : DX_DCL_INPUT_PS;
+         op = s->sv ? (s->sv == DX_SV_POSITION || s->sv == DX_SV_RTINDEX ? DX_DCL_INPUT_PS_SIV
+               : DX_DCL_INPUT_PS_SGV) : DX_DCL_INPUT_PS;
          if (op != DX_DCL_INPUT_PS_SGV)
             fl = (uint32_t)s->interp << 11;
       }

Externals/libretro-common/gfx/shaders/rslc_emit.c

@@ -5062,6 +5062,7 @@ static void pr_hlsl_semantic(struct rslc_pr *p, const struct rslc_var *v, bool i
          case RSLC_BI_FRONTFACING:   pr_s(p, "SV_IsFrontFace"); return;
          case RSLC_BI_SAMPLEID:      pr_s(p, "SV_SampleIndex"); return;
 #ifdef RSLC_EXTENDED
+         case RSLC_BI_LAYER:         pr_s(p, "SV_RenderTargetArrayIndex"); return;
          case RSLC_BI_GLOBALINVOCATIONID:   pr_s(p, "SV_DispatchThreadID"); return;
          case RSLC_BI_LOCALINVOCATIONID:    pr_s(p, "SV_GroupThreadID"); return;
          case RSLC_BI_WORKGROUPID:          pr_s(p, "SV_GroupID"); return;
@@ -5173,6 +5174,7 @@ static bool pr_hlsl_builtin_in(const struct rslc_var *v, bool *in_struct)
       case RSLC_BI_FRONTFACING:
       case RSLC_BI_SAMPLEID:
 #ifdef RSLC_EXTENDED
+      case RSLC_BI_LAYER:
       case RSLC_BI_GLOBALINVOCATIONID:
       case RSLC_BI_LOCALINVOCATIONID:
       case RSLC_BI_WORKGROUPID:
@@ -6417,6 +6419,7 @@ static bool pr_msl(struct rslc_pr *p, struct rslc_result *result)
          case RSLC_BI_INSTANCEINDEX: attr = "uint gl_InstanceIndex_in [[instance_id]]"; break;
          case RSLC_BI_SAMPLEID:      attr = "uint gl_SampleID_in [[sample_id]]"; break;
 #ifdef RSLC_EXTENDED
+         case RSLC_BI_LAYER:         attr = "uint gl_Layer_in [[render_target_array_index]]"; break;
          case RSLC_BI_GLOBALINVOCATIONID:
             attr = "uint3 gl_GlobalInvocationID [[thread_position_in_grid]]"; break;
          case RSLC_BI_LOCALINVOCATIONID:

Externals/libretro-common/gfx/shaders/rslc_front.c

@@ -3492,7 +3492,8 @@ static bool rslc_p_is_lvalue(struct rslc_parser *p, uint32_t e)
          if (v->storage == RSLC_ST_BUILTIN)
             return v->builtin == RSLC_BI_POSITION || v->builtin == RSLC_BI_FRAGDEPTH
                || v->builtin == RSLC_BI_POINTSIZE || v->builtin == RSLC_BI_CLIPDISTANCE
-               || v->builtin == RSLC_BI_CULLDISTANCE || v->builtin == RSLC_BI_LAYER;
+               || v->builtin == RSLC_BI_CULLDISTANCE
+               || (v->builtin == RSLC_BI_LAYER && v->dir == RSLC_DIR_OUT);
          return true;
       }
       case RSLC_OP_MEMBER:
@@ -6210,7 +6211,8 @@ static bool rslc_p_run(struct rslc_ctx *c)
 #ifdef RSLC_EXTENDED
       if (!rslc_p_builtin_var(p, "gl_SampleID", p->t_int, RSLC_BI_SAMPLEID, RSLC_DIR_IN)
             || !rslc_p_builtin_var(p, "gl_HelperInvocation", p->t_bool,
-                  RSLC_BI_HELPERINVOCATION, RSLC_DIR_IN))
+                  RSLC_BI_HELPERINVOCATION, RSLC_DIR_IN)
+            || !rslc_p_builtin_var(p, "gl_Layer", p->t_int, RSLC_BI_LAYER, RSLC_DIR_IN))
          return false;
 #endif
    }
@@ -6435,7 +6437,8 @@ struct rslc_builder *rslc_b_begin(const struct rslc_opts *opts, enum rslc_stage
          || !rslc_p_builtin_var(p, "gl_FrontFacing", p->t_bool, RSLC_BI_FRONTFACING, RSLC_DIR_IN))
       return b;
 #ifdef RSLC_EXTENDED
-   else if (!rslc_p_builtin_var(p, "gl_SampleID", p->t_int, RSLC_BI_SAMPLEID, RSLC_DIR_IN))
+   else if (!rslc_p_builtin_var(p, "gl_SampleID", p->t_int, RSLC_BI_SAMPLEID, RSLC_DIR_IN)
+         || !rslc_p_builtin_var(p, "gl_Layer", p->t_int, RSLC_BI_LAYER, RSLC_DIR_IN))
       return b;
 #endif
    return b;

Externals/libretro-common/gfx/shaders/rslc_ir.c

@@ -1230,6 +1230,7 @@ struct spv_emit
    bool                 need_groupnonuniformarith;
    bool                 need_sampledbuffer;
    bool                 need_samplerateshading;
+   bool                 need_geometry;   /* a pixel stage reading gl_Layer */
    bool                 need_clipdistance;
    bool                 writes_fragdepth;   /* the entry point declares DepthReplacing */
    bool                 need_culldistance;
@@ -4699,8 +4700,12 @@ static bool spv_builtin_var(struct spv_emit *e, const struct rslc_var *v)
       return false;
    if (!spv_decorate1(e, id, SPV_DEC_BUILTIN, bi) || !spv_w(e, &e->entry_iface, id))
       return false;
-   /* an integer fragment input is flat, a builtin too */
-   if (v->builtin == RSLC_BI_SAMPLEID && !spv_decorate(e, id, SPV_DEC_FLAT))
+   /* an integer fragment input is flat, a builtin too; a pixel stage
+    * reading the layer needs the geometry capability */
+   if (v->builtin == RSLC_BI_LAYER && sc == SPV_SC_INPUT)
+      e->need_geometry = true;
+   if ((v->builtin == RSLC_BI_SAMPLEID || (v->builtin == RSLC_BI_LAYER && sc == SPV_SC_INPUT))
+         && !spv_decorate(e, id, SPV_DEC_FLAT))
       return false;
    if ((v->precision == RSLC_PREC_LOW || v->precision == RSLC_PREC_MEDIUM)
          && !spv_decorate(e, id, SPV_DEC_RELAXEDPRECISION))
@@ -5070,7 +5075,7 @@ static bool rslc_emit_spirv(struct rslc_ctx *c, struct rslc_result *result)
    /* header-ish sections */
    if (!spv_inst1(e, SPV_SEC_CAPS, SpvOpCapability, SPV_CAP_SHADER))
       return false;
-   if (c->stage == RSLC_STAGE_GEOMETRY
+   if ((c->stage == RSLC_STAGE_GEOMETRY || e->need_geometry)
          && !spv_inst1(e, SPV_SEC_CAPS, SpvOpCapability, SPV_CAP_GEOMETRY))
       return false;
    if (e->need_sampledbuffer && !spv_inst1(e, SPV_SEC_CAPS, SpvOpCapability, SPV_CAP_SAMPLEDBUFFER))

Externals/libretro-common/gfx/shaders/rslc_share.h

@@ -395,7 +395,7 @@ struct rslc_var
 #define RSLC_BI_CLIPDISTANCE 9   /* RSLC_EXTENDED */
 #define RSLC_BI_CULLDISTANCE 10  /* RSLC_EXTENDED */
 #define RSLC_BI_INVOCATIONID 11  /* RSLC_EXTENDED, geometry */
-#define RSLC_BI_LAYER        12  /* RSLC_EXTENDED, geometry */
+#define RSLC_BI_LAYER        12  /* RSLC_EXTENDED, geometry out, fragment in */
 #define RSLC_BI_GLOBALINVOCATIONID 13   /* RSLC_EXTENDED, compute */
 #define RSLC_BI_LOCALINVOCATIONID  14
 #define RSLC_BI_WORKGROUPID        15
@@ -425,9 +425,10 @@ struct rslc_var
  * the least maxClipDistances Vulkan guarantees. */
 #define RSLC_MAX_CLIP 8
 
-/* The integer builtins HLSL and MSL hand over as uint. */
+/* The integer builtins HLSL and MSL hand over as uint (gl_Layer: a
+ * pixel stage's, the only stage those printers take it in). */
 #define RSLC_BI_IS_UINT_IN(b) ((b) == RSLC_BI_VERTEXINDEX || (b) == RSLC_BI_INSTANCEINDEX \
-      || (b) == RSLC_BI_SAMPLEID)
+      || (b) == RSLC_BI_SAMPLEID || (b) == RSLC_BI_LAYER)
 
 /* A uniform block or push-constant block. */
 struct rslc_blockdecl