Revert "glsl: Move ForceGLSLAbsSqrt handling to glsl-to-nir."

This reverts commit 46bf687882.

We wont be removing this lowering file and having this workaround in
glsl_to_nir() creates a dependency on the const values that we could
otherwise avoid, so lets just move this back. Dropping the consts
will be useful in a follow up series that aims to drop all the glsl
ir function inlining code by converting builtin functions to nir.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32239>

src/compiler/glsl/glsl_parser_extras.cpp

@@ -2260,7 +2260,8 @@ opt_shader_and_create_symbol_table(const struct gl_constants *consts,
                           consts->GLSLHasHalfFloatPacking);
    do_mat_op_to_vec(shader->ir);
 
-   lower_instructions(shader->ir, exts->ARB_gpu_shader5);
+   lower_instructions(shader->ir, consts->ForceGLSLAbsSqrt,
+                      exts->ARB_gpu_shader5);
 
    do_vec_index_to_cond_assign(shader->ir);
 

src/compiler/glsl/glsl_to_nir.cpp

@@ -149,8 +149,6 @@ private:
 
    void adjust_sparse_variable(nir_deref_instr *var_deref, const glsl_type *type,
                                nir_def *dest);
-
-   const struct gl_constants *consts;
 };
 
 /*
@@ -204,7 +202,6 @@ glsl_to_nir(const struct gl_constants *consts,
 nir_visitor::nir_visitor(const struct gl_constants *consts, nir_shader *shader,
                          const uint8_t *src_blake3)
 {
-   this->consts = consts;
    this->shader = shader;
    this->is_global = true;
    this->var_table = _mesa_pointer_hash_table_create(NULL);
@@ -2076,19 +2073,8 @@ nir_visitor::visit(ir_expression *ir)
                                        : nir_isign(&b, srcs[0]);
       break;
    case ir_unop_rcp:  result = nir_frcp(&b, srcs[0]);  break;
-
-   case ir_unop_rsq:
-      if (consts->ForceGLSLAbsSqrt)
-         srcs[0] = nir_fabs(&b, srcs[0]);
-      result = nir_frsq(&b, srcs[0]);
-      break;
-
-   case ir_unop_sqrt:
-      if (consts->ForceGLSLAbsSqrt)
-         srcs[0] = nir_fabs(&b, srcs[0]);
-      result = nir_fsqrt(&b, srcs[0]);
-      break;
-
+   case ir_unop_rsq:  result = nir_frsq(&b, srcs[0]);  break;
+   case ir_unop_sqrt: result = nir_fsqrt(&b, srcs[0]); break;
    case ir_unop_exp:  result = nir_fexp2(&b, nir_fmul_imm(&b, srcs[0], M_LOG2E)); break;
    case ir_unop_log:  result = nir_fmul_imm(&b, nir_flog2(&b, srcs[0]), 1.0 / M_LOG2E); break;
    case ir_unop_exp2: result = nir_fexp2(&b, srcs[0]); break;

src/compiler/glsl/ir_optimization.h

@@ -53,7 +53,7 @@ bool do_minmax_prune(exec_list *instructions);
 bool do_tree_grafting(exec_list *instructions);
 bool do_vec_index_to_cond_assign(exec_list *instructions);
 bool lower_instructions(exec_list *instructions,
-                        bool have_gpu_shader5);
+                        bool force_abs_sqrt, bool have_gpu_shader5);
 bool lower_packing_builtins(exec_list *instructions,
                             bool has_shading_language_packing,
                             bool has_gpu_shader5,

src/compiler/glsl/lower_instructions.cpp

@@ -43,6 +43,7 @@
 #define FIND_LSB_TO_FLOAT_CAST    0x20000
 #define FIND_MSB_TO_FLOAT_CAST    0x40000
 #define IMUL_HIGH_TO_MUL          0x80000
+#define SQRT_TO_ABS_SQRT          0x200000
 
 using namespace ir_builder;
 
@@ -65,6 +66,7 @@ private:
    void find_lsb_to_float_cast(ir_expression *ir);
    void find_msb_to_float_cast(ir_expression *ir);
    void imul_high_to_mul(ir_expression *ir);
+   void sqrt_to_abs_sqrt(ir_expression *ir);
 
    ir_expression *_carry(operand a, operand b);
 
@@ -82,9 +84,11 @@ private:
 #define lowering(x) (this->lower & x)
 
 bool
-lower_instructions(exec_list *instructions,bool have_gpu_shader5)
+lower_instructions(exec_list *instructions, bool force_abs_sqrt,
+                   bool have_gpu_shader5)
 {
    unsigned what_to_lower =
+      (force_abs_sqrt ? SQRT_TO_ABS_SQRT : 0) |
       /* Assume that if ARB_gpu_shader5 is not supported then all of the
        * extended integer functions need lowering.  It may be necessary to add
        * some caps for individual instructions.
@@ -489,6 +493,13 @@ lower_instructions_visitor::imul_high_to_mul(ir_expression *ir)
    }
 }
 
+void
+lower_instructions_visitor::sqrt_to_abs_sqrt(ir_expression *ir)
+{
+   ir->operands[0] = new(ir) ir_expression(ir_unop_abs, ir->operands[0]);
+   this->progress = true;
+}
+
 ir_visitor_status
 lower_instructions_visitor::visit_leave(ir_expression *ir)
 {
@@ -517,6 +528,12 @@ lower_instructions_visitor::visit_leave(ir_expression *ir)
          imul_high_to_mul(ir);
       break;
 
+   case ir_unop_rsq:
+   case ir_unop_sqrt:
+      if (lowering(SQRT_TO_ABS_SQRT))
+         sqrt_to_abs_sqrt(ir);
+      break;
+
    default:
       return visit_continue;
    }

src/compiler/glsl/test_optpass.cpp

@@ -87,7 +87,7 @@ do_optimization(struct exec_list *ir, const char *optimization,
       return do_vec_index_to_cond_assign(ir);
    } else if (sscanf(optimization, "lower_instructions ( %d ) ",
                      &int_0) == 1) {
-      return lower_instructions(ir, false);
+      return lower_instructions(ir, false, false);
    } else {
       printf("Unrecognized optimization %s\n", optimization);
       exit(EXIT_FAILURE);