nir: Fix OpAtomicCounterIDecrement for uniform atomic counters

From the SPIR-V 1.0 specification, section 3.32.18, "Atomic
Instructions":

   "OpAtomicIDecrement:
    <skip>
    The instruction's result is the Original Value."

However, we were implementing it, for uniform atomic counters, as a
pre-decrement operation, as was the one available from GLSL.

Renamed the former nir intrinsic 'atomic_counter_dec*' to
'atomic_counter_pre_dec*' for clarification purposes, as it implements
a pre-decrement operation as specified for GLSL. From GLSL 4.50 spec,
section 8.10, "Atomic Counter Functions":

   "uint atomicCounterDecrement (atomic_uint c)

    Atomically
    1. decrements the counter for c, and
    2. returns the value resulting from the decrement operation.

    These two steps are done atomically with respect to the atomic
    counter functions in this table."

Added a new nir intrinsic 'atomic_counter_post_dec*' which implements
a post-decrement operation as required by SPIR-V.

v2: (Timothy Arceri)
   * Add extra spec quotes on commit message
   * Use "post" instead "pos" to avoid confusion with "position"

Signed-off-by: Antia Puentes <apuentes@igalia.com>
Signed-off-by: Alejandro Piñeiro <apinheiro@igalia.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>

diff --git a/src/compiler/glsl/gl_nir_lower_atomics.c b/src/compiler/glsl/gl_nir_lower_atomics.c
index 293730966fdca584b6fbac11e8b4fd11308d2a1d..36e273c45d2c50bcc9b4a49301ff9d3de6a8591a 100644 (file)
--- a/src/compiler/glsl/gl_nir_lower_atomics.c
+++ b/src/compiler/glsl/gl_nir_lower_atomics.c
@@ -53,8 +53,12 @@ lower_deref_instr(nir_builder *b, nir_intrinsic_instr *instr,
       op = nir_intrinsic_atomic_counter_inc;
       break;
 
-   case nir_intrinsic_atomic_counter_dec_deref:
-      op = nir_intrinsic_atomic_counter_dec;
+   case nir_intrinsic_atomic_counter_pre_dec_deref:
+      op = nir_intrinsic_atomic_counter_pre_dec;
+      break;
+
+   case nir_intrinsic_atomic_counter_post_dec_deref:
+      op = nir_intrinsic_atomic_counter_post_dec;
       break;
 
    case nir_intrinsic_atomic_counter_add_deref:

diff --git a/src/compiler/glsl/glsl_to_nir.cpp b/src/compiler/glsl/glsl_to_nir.cpp
index d3a3fb9b085e6ef128b6a4d13f527c742475b6c2..2d76c7e6cfec656c74f0b97913bd51f087aed018 100644 (file)
--- a/src/compiler/glsl/glsl_to_nir.cpp
+++ b/src/compiler/glsl/glsl_to_nir.cpp
@@ -630,7 +630,7 @@ nir_visitor::visit(ir_call *ir)
          op = nir_intrinsic_atomic_counter_inc_deref;
          break;
       case ir_intrinsic_atomic_counter_predecrement:
-         op = nir_intrinsic_atomic_counter_dec_deref;
+         op = nir_intrinsic_atomic_counter_pre_dec_deref;
          break;
       case ir_intrinsic_atomic_counter_add:
          op = nir_intrinsic_atomic_counter_add_deref;
@@ -831,7 +831,7 @@ nir_visitor::visit(ir_call *ir)
       switch (op) {
       case nir_intrinsic_atomic_counter_read_deref:
       case nir_intrinsic_atomic_counter_inc_deref:
-      case nir_intrinsic_atomic_counter_dec_deref:
+      case nir_intrinsic_atomic_counter_pre_dec_deref:
       case nir_intrinsic_atomic_counter_add_deref:
       case nir_intrinsic_atomic_counter_min_deref:
       case nir_intrinsic_atomic_counter_max_deref:

diff --git a/src/compiler/nir/nir_intrinsics.py b/src/compiler/nir/nir_intrinsics.py
index 44a5b76beb6d6e73623bc4a83183549b24466659..919aa609f8afc3db09d08beea794ecf9a4fe8298 100644 (file)
--- a/src/compiler/nir/nir_intrinsics.py
+++ b/src/compiler/nir/nir_intrinsics.py
@@ -270,7 +270,8 @@ def atomic3(name):
     intrinsic(name, src_comp=[1, 1, 1], dest_comp=1, indices=[BASE])
 
 atomic("atomic_counter_inc")
-atomic("atomic_counter_dec")
+atomic("atomic_counter_pre_dec")
+atomic("atomic_counter_post_dec")
 atomic("atomic_counter_read", flags=[CAN_ELIMINATE])
 atomic2("atomic_counter_add")
 atomic2("atomic_counter_min")

diff --git a/src/compiler/nir/nir_lower_atomics_to_ssbo.c b/src/compiler/nir/nir_lower_atomics_to_ssbo.c
index 934ae81d750595af5b9427b44e7b2f9801d8c6d7..6ebd3632288f67acf01bb9ebe90a99864965d59a 100644 (file)
--- a/src/compiler/nir/nir_lower_atomics_to_ssbo.c
+++ b/src/compiler/nir/nir_lower_atomics_to_ssbo.c
@@ -71,7 +71,8 @@ lower_instr(nir_intrinsic_instr *instr, unsigned ssbo_offset, nir_builder *b)
       return true;
    case nir_intrinsic_atomic_counter_inc:
    case nir_intrinsic_atomic_counter_add:
-   case nir_intrinsic_atomic_counter_dec:
+   case nir_intrinsic_atomic_counter_pre_dec:
+   case nir_intrinsic_atomic_counter_post_dec:
       /* inc and dec get remapped to add: */
       op = nir_intrinsic_ssbo_atomic_add;
       break;
@@ -119,7 +120,8 @@ lower_instr(nir_intrinsic_instr *instr, unsigned ssbo_offset, nir_builder *b)
       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
       new_instr->src[2] = nir_src_for_ssa(temp);
       break;
-   case nir_intrinsic_atomic_counter_dec:
+   case nir_intrinsic_atomic_counter_pre_dec:
+   case nir_intrinsic_atomic_counter_post_dec:
       /* remapped to ssbo_atomic_add: { buffer_idx, offset, -1 } */
       /* NOTE semantic difference so we adjust the return value below */
       temp = nir_imm_int(b, -1);
@@ -148,7 +150,7 @@ lower_instr(nir_intrinsic_instr *instr, unsigned ssbo_offset, nir_builder *b)
    nir_instr_insert_before(&instr->instr, &new_instr->instr);
    nir_instr_remove(&instr->instr);
 
-   if (instr->intrinsic == nir_intrinsic_atomic_counter_dec) {
+   if (instr->intrinsic == nir_intrinsic_atomic_counter_pre_dec) {
       b->cursor = nir_after_instr(&new_instr->instr);
       nir_ssa_def *result = nir_iadd(b, &new_instr->dest.ssa, temp);
       nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(result));

diff --git a/src/compiler/spirv/spirv_to_nir.c b/src/compiler/spirv/spirv_to_nir.c
index 9d2f57cef94e803a884db4324d7d9c698cd348f0..fb4211193fba1e8140a6988f7db1869964ea7f3a 100644 (file)
--- a/src/compiler/spirv/spirv_to_nir.c
+++ b/src/compiler/spirv/spirv_to_nir.c
@@ -2519,7 +2519,7 @@ get_uniform_nir_atomic_op(struct vtn_builder *b, SpvOp opcode)
    OP(AtomicExchange,         exchange)
    OP(AtomicCompareExchange,  comp_swap)
    OP(AtomicIIncrement,       inc_deref)
-   OP(AtomicIDecrement,       dec_deref)
+   OP(AtomicIDecrement,       post_dec_deref)
    OP(AtomicIAdd,             add_deref)
    OP(AtomicISub,             add_deref)
    OP(AtomicUMin,             min_deref)