gallium+glsl: Remove EmitNoSat/PIPE_CAP_VERTEX_SHADER_SATURATE

The drivers not setting it were:

- nv30, which gets lowering using NIR's lower_fsat flag.
- r300, which gets lowering using NIR's lower_fsat flag.
- a2xx, which has was getting it optimized back to fsat anyway.

This drops the check for the cap from gallium nine.  While nine does have
a non-nir path, I think it's safe to assume that if you have SM3
texturing, you can do fsat.

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16823>

src/compiler/glsl/ir_optimization.h

@@ -42,7 +42,6 @@ struct gl_shader_program;
 #define LDEXP_TO_ARITH     0x80
 #define CARRY_TO_ARITH     0x100
 #define BORROW_TO_ARITH    0x200
-#define SAT_TO_CLAMP       0x400
 #define DOPS_TO_DFRAC      0x800
 #define DFREXP_DLDEXP_TO_ARITH    0x1000
 #define BIT_COUNT_TO_MATH         0x02000

src/compiler/glsl/lower_instructions.cpp

@@ -38,7 +38,6 @@
  * - LDEXP_TO_ARITH
  * - CARRY_TO_ARITH
  * - BORROW_TO_ARITH
- * - SAT_TO_CLAMP
  * - DOPS_TO_DFRAC
  *
  * SUB_TO_ADD_NEG:
@@ -97,10 +96,6 @@
  * ----------------
  * Converts ir_borrow into (x < y).
  *
- * SAT_TO_CLAMP:
- * -------------
- * Converts ir_unop_saturate into min(max(x, 0.0), 1.0)
- *
  * DOPS_TO_DFRAC:
  * --------------
  * Converts double trunc, ceil, floor, round to fract
@@ -142,7 +137,6 @@ private:
    void dfrexp_exp_to_arith(ir_expression *);
    void carry_to_arith(ir_expression *);
    void borrow_to_arith(ir_expression *);
-   void sat_to_clamp(ir_expression *);
    void double_dot_to_fma(ir_expression *);
    void double_lrp(ir_expression *);
    void dceil_to_dfrac(ir_expression *);
@@ -754,26 +748,6 @@ lower_instructions_visitor::borrow_to_arith(ir_expression *ir)
    this->progress = true;
 }
 
-void
-lower_instructions_visitor::sat_to_clamp(ir_expression *ir)
-{
-   /* Translates
-    *   ir_unop_saturate x
-    * into
-    *   ir_binop_min (ir_binop_max(x, 0.0), 1.0)
-    */
-
-   ir->operation = ir_binop_min;
-   ir->init_num_operands();
-
-   ir_constant *zero = _imm_fp(ir, ir->operands[0]->type, 0.0);
-   ir->operands[0] = new(ir) ir_expression(ir_binop_max, ir->operands[0]->type,
-                                           ir->operands[0], zero);
-   ir->operands[1] = _imm_fp(ir, ir->operands[0]->type, 1.0);
-
-   this->progress = true;
-}
-
 void
 lower_instructions_visitor::double_dot_to_fma(ir_expression *ir)
 {
@@ -1677,11 +1651,6 @@ lower_instructions_visitor::visit_leave(ir_expression *ir)
          borrow_to_arith(ir);
       break;
 
-   case ir_unop_saturate:
-      if (lowering(SAT_TO_CLAMP))
-         sat_to_clamp(ir);
-      break;
-
    case ir_unop_trunc:
       if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
          dtrunc_to_dfrac(ir);

src/compiler/glsl/opt_algebraic.cpp

@@ -860,7 +860,7 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
 
    case ir_binop_min:
    case ir_binop_max:
-      if (!ir->type->is_float() || options->EmitNoSat)
+      if (!ir->type->is_float())
          break;
 
       /* Replace min(max) operations and its commutative combinations with