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glsl: Retire ldexp lowering in favor of the nir lowering flag.

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Compilers need to set the nir flag anyway for vulkan, so just pass ldexp
through to NIR and let that handle it.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22083>
This commit is contained in:
Emma Anholt
2023-03-22 13:20:03 -07:00
committed by Marge Bot
parent 675f4ff596
commit 2a33ea95d6
33 changed files with 12 additions and 210 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/compiler/glsl/ir_optimization.h
+1 -1
View File
@@ -59,7 +59,7 @@ bool do_tree_grafting(exec_list *instructions);
bool do_vec_index_to_cond_assign(exec_list *instructions);
bool lower_discard(exec_list *instructions);
void lower_discard_flow(exec_list *instructions);
bool lower_instructions(exec_list *instructions, bool have_ldexp,
bool lower_instructions(exec_list *instructions,
bool have_dfrexp, bool have_dround,
bool have_gpu_shader5);
bool lower_clip_cull_distance(struct gl_shader_program *prog,
src/compiler/glsl/lower_instructions.cpp
+1 -175
View File
@@ -30,13 +30,8 @@
* rather than in each driver backend.
*
* Currently supported transformations:
* - LDEXP_TO_ARITH
* - DOPS_TO_DFRAC
*
* LDEXP_TO_ARITH:
* -------------
* Converts ir_binop_ldexp to arithmetic and bit operations for float sources.
*
* DFREXP_DLDEXP_TO_ARITH:
* ---------------
* Converts ir_binop_ldexp, ir_unop_frexp_sig, and ir_unop_frexp_exp to
@@ -57,7 +52,6 @@
#include <math.h>
/* Operations for lower_instructions() */
#define LDEXP_TO_ARITH 0x80
#define DOPS_TO_DFRAC 0x800
#define DFREXP_DLDEXP_TO_ARITH 0x1000
#define FIND_LSB_TO_FLOAT_CAST 0x20000
@@ -80,7 +74,6 @@ public:
private:
unsigned lower; /** Bitfield of which operations to lower */
void ldexp_to_arith(ir_expression *);
void dldexp_to_arith(ir_expression *);
void dfrexp_sig_to_arith(ir_expression *);
void dfrexp_exp_to_arith(ir_expression *);
@@ -111,11 +104,10 @@ private:
#define lowering(x) (this->lower & x)
bool
lower_instructions(exec_list *instructions, bool have_ldexp, bool have_dfrexp,
lower_instructions(exec_list *instructions, bool have_dfrexp,
bool have_dround, bool have_gpu_shader5)
{
unsigned what_to_lower =
(have_ldexp ? 0 : LDEXP_TO_ARITH) |
(have_dfrexp ? 0 : DFREXP_DLDEXP_TO_ARITH) |
(have_dround ? 0 : DOPS_TO_DFRAC) |
/* Assume that if ARB_gpu_shader5 is not supported then all of the
@@ -132,170 +124,6 @@ lower_instructions(exec_list *instructions, bool have_ldexp, bool have_dfrexp,
return v.progress;
}
void
lower_instructions_visitor::ldexp_to_arith(ir_expression *ir)
{
/* Translates
* ir_binop_ldexp x exp
* into
*
* extracted_biased_exp = rshift(bitcast_f2i(abs(x)), exp_shift);
* resulting_biased_exp = min(extracted_biased_exp + exp, 255);
*
* if (extracted_biased_exp >= 255)
* return x; // +/-inf, NaN
*
* sign_mantissa = bitcast_f2u(x) & sign_mantissa_mask;
*
* if (min(resulting_biased_exp, extracted_biased_exp) < 1)
* resulting_biased_exp = 0;
* if (resulting_biased_exp >= 255 ||
* min(resulting_biased_exp, extracted_biased_exp) < 1) {
* sign_mantissa &= sign_mask;
* }
*
* return bitcast_u2f(sign_mantissa |
* lshift(i2u(resulting_biased_exp), exp_shift));
*
* which we can't actually implement as such, since the GLSL IR doesn't
* have vectorized if-statements. We actually implement it without branches
* using conditional-select:
*
* extracted_biased_exp = rshift(bitcast_f2i(abs(x)), exp_shift);
* resulting_biased_exp = min(extracted_biased_exp + exp, 255);
*
* sign_mantissa = bitcast_f2u(x) & sign_mantissa_mask;
*
* flush_to_zero = lequal(min(resulting_biased_exp, extracted_biased_exp), 0);
* resulting_biased_exp = csel(flush_to_zero, 0, resulting_biased_exp)
* zero_mantissa = logic_or(flush_to_zero,
* gequal(resulting_biased_exp, 255));
* sign_mantissa = csel(zero_mantissa, sign_mantissa & sign_mask, sign_mantissa);
*
* result = sign_mantissa |
* lshift(i2u(resulting_biased_exp), exp_shift));
*
* return csel(extracted_biased_exp >= 255, x, bitcast_u2f(result));
*
* The definition of ldexp in the GLSL spec says:
*
* "If this product is too large to be represented in the
* floating-point type, the result is undefined."
*
* However, the definition of ldexp in the GLSL ES spec does not contain
* this sentence, so we do need to handle overflow correctly.
*
* There is additional language limiting the defined range of exp, but this
* is merely to allow implementations that store 2^exp in a temporary
* variable.
*/
const unsigned vec_elem = ir->type->vector_elements;
/* Types */
const glsl_type *ivec = glsl_type::get_instance(GLSL_TYPE_INT, vec_elem, 1);
const glsl_type *uvec = glsl_type::get_instance(GLSL_TYPE_UINT, vec_elem, 1);
const glsl_type *bvec = glsl_type::get_instance(GLSL_TYPE_BOOL, vec_elem, 1);
/* Temporary variables */
ir_variable *x = new(ir) ir_variable(ir->type, "x", ir_var_temporary);
ir_variable *exp = new(ir) ir_variable(ivec, "exp", ir_var_temporary);
ir_variable *result = new(ir) ir_variable(uvec, "result", ir_var_temporary);
ir_variable *extracted_biased_exp =
new(ir) ir_variable(ivec, "extracted_biased_exp", ir_var_temporary);
ir_variable *resulting_biased_exp =
new(ir) ir_variable(ivec, "resulting_biased_exp", ir_var_temporary);
ir_variable *sign_mantissa =
new(ir) ir_variable(uvec, "sign_mantissa", ir_var_temporary);
ir_variable *flush_to_zero =
new(ir) ir_variable(bvec, "flush_to_zero", ir_var_temporary);
ir_variable *zero_mantissa =
new(ir) ir_variable(bvec, "zero_mantissa", ir_var_temporary);
ir_instruction &i = *base_ir;
/* Copy <x> and <exp> arguments. */
i.insert_before(x);
i.insert_before(assign(x, ir->operands[0]));
i.insert_before(exp);
i.insert_before(assign(exp, ir->operands[1]));
/* Extract the biased exponent from <x>. */
i.insert_before(extracted_biased_exp);
i.insert_before(assign(extracted_biased_exp,
rshift(bitcast_f2i(abs(x)),
new(ir) ir_constant(23, vec_elem))));
/* The definition of ldexp in the GLSL 4.60 spec says:
*
* "If exp is greater than +128 (single-precision) or +1024
* (double-precision), the value returned is undefined. If exp is less
* than -126 (single-precision) or -1022 (double-precision), the value
* returned may be flushed to zero."
*
* So we do not have to guard against the possibility of addition overflow,
* which could happen when exp is close to INT_MAX. Addition underflow
* cannot happen (the worst case is 0 + (-INT_MAX)).
*/
i.insert_before(resulting_biased_exp);
i.insert_before(assign(resulting_biased_exp,
min2(add(extracted_biased_exp, exp),
new(ir) ir_constant(255, vec_elem))));
i.insert_before(sign_mantissa);
i.insert_before(assign(sign_mantissa,
bit_and(bitcast_f2u(x),
new(ir) ir_constant(0x807fffffu, vec_elem))));
/* We flush to zero if the original or resulting biased exponent is 0,
* indicating a +/-0.0 or subnormal input or output.
*
* The mantissa is set to 0 if the resulting biased exponent is 255, since
* an overflow should produce a +/-inf result.
*
* Note that NaN inputs are handled separately.
*/
i.insert_before(flush_to_zero);
i.insert_before(assign(flush_to_zero,
lequal(min2(resulting_biased_exp,
extracted_biased_exp),
ir_constant::zero(ir, ivec))));
i.insert_before(assign(resulting_biased_exp,
csel(flush_to_zero,
ir_constant::zero(ir, ivec),
resulting_biased_exp)));
i.insert_before(zero_mantissa);
i.insert_before(assign(zero_mantissa,
logic_or(flush_to_zero,
equal(resulting_biased_exp,
new(ir) ir_constant(255, vec_elem)))));
i.insert_before(assign(sign_mantissa,
csel(zero_mantissa,
bit_and(sign_mantissa,
new(ir) ir_constant(0x80000000u, vec_elem)),
sign_mantissa)));
i.insert_before(result);
i.insert_before(assign(result,
bitfield_insert(sign_mantissa,
i2u(resulting_biased_exp),
new(ir) ir_constant(23u, vec_elem),
new(ir) ir_constant(8u, vec_elem))));
ir->operation = ir_triop_csel;
ir->init_num_operands();
ir->operands[0] = gequal(extracted_biased_exp,
new(ir) ir_constant(255, vec_elem));
ir->operands[1] = new(ir) ir_dereference_variable(x);
ir->operands[2] = bitcast_u2f(result);
this->progress = true;
}
void
lower_instructions_visitor::dldexp_to_arith(ir_expression *ir)
{
@@ -1100,8 +928,6 @@ lower_instructions_visitor::visit_leave(ir_expression *ir)
break;
case ir_binop_ldexp:
if (lowering(LDEXP_TO_ARITH) && ir->type->is_float())
ldexp_to_arith(ir);
if (lowering(DFREXP_DLDEXP_TO_ARITH) && ir->type->is_double())
dldexp_to_arith(ir);
break;
src/compiler/glsl/test_optpass.cpp
+1 -1
View File
@@ -93,7 +93,7 @@ do_optimization(struct exec_list *ir, const char *optimization,
return lower_discard(ir);
} else if (sscanf(optimization, "lower_instructions ( %d ) ",
&int_0) == 1) {
return lower_instructions(ir, false, false, false, false);
return lower_instructions(ir, false, false, false);
} else {
printf("Unrecognized optimization %s\n", optimization);
exit(EXIT_FAILURE);