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author | Kristian Høgsberg Kristensen <krh@bitplanet.net> | 2015-11-04 14:58:54 -0800 |
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committer | Kristian Høgsberg Kristensen <krh@bitplanet.net> | 2015-11-10 12:02:46 -0800 |
commit | 96b22fb080894ba1840af2372f28a46cc0f40c76 (patch) | |
tree | 197f2454ecfd1778eeea2d81146682ff35fce01e /src/glsl/ast_function.cpp | |
parent | 60dd5287ff8dbbbe0dbe76bdff6d13c7a5ea9ef0 (diff) | |
download | external_mesa3d-96b22fb080894ba1840af2372f28a46cc0f40c76.zip external_mesa3d-96b22fb080894ba1840af2372f28a46cc0f40c76.tar.gz external_mesa3d-96b22fb080894ba1840af2372f28a46cc0f40c76.tar.bz2 |
glsl: Use array deref for access to vector components
We've assumed that we could lower per-component vector access from
vec[i] = scalar
to
vec = ir_triop_vector_insert(vec, scalar, i)
but with SSBOs (and compute shader SLM and tesselation outputs) this is
no longer valid. If a vector is "externally visible", multiple threads
can write independent components simultaneously. With lowering to
ir_triop_vector_insert, each thread read the entire vector, changes one
component, then writes out the entire vector. This is racy.
Instead of generating a ir_binop_vector_extract when we see v[i], we
generate ir_dereference_array. We then add a lowering pass to lower the
ir_dereference_array to ir_binop_vector_extract for rvalues and for to
vector_insert for lvalues in a separate lowering pass.
The resulting IR is the same as before, but we now have a window between
ast->ir conversion and the lowering pass where v[i] appears in the IR as
an array deref. This lets us run lowering passes that lower the vector
access to I/O (eg for SSBO load/store) before we lower the per-component
access to full vector writes.
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Signed-off-by: Kristian Høgsberg Kristensen <krh@bitplanet.net>
Diffstat (limited to 'src/glsl/ast_function.cpp')
-rw-r--r-- | src/glsl/ast_function.cpp | 24 |
1 files changed, 6 insertions, 18 deletions
diff --git a/src/glsl/ast_function.cpp b/src/glsl/ast_function.cpp index e4e4a3f..5584470 100644 --- a/src/glsl/ast_function.cpp +++ b/src/glsl/ast_function.cpp @@ -256,18 +256,10 @@ verify_parameter_modes(_mesa_glsl_parse_state *state, actual->variable_referenced()->name); return false; } else if (!actual->is_lvalue()) { - /* Even though ir_binop_vector_extract is not an l-value, let it - * slop through. generate_call will handle it correctly. - */ - ir_expression *const expr = ((ir_rvalue *) actual)->as_expression(); - if (expr == NULL - || expr->operation != ir_binop_vector_extract - || !expr->operands[0]->is_lvalue()) { - _mesa_glsl_error(&loc, state, - "function parameter '%s %s' is not an lvalue", - mode, formal->name); - return false; - } + _mesa_glsl_error(&loc, state, + "function parameter '%s %s' is not an lvalue", + mode, formal->name); + return false; } } @@ -376,12 +368,8 @@ fix_parameter(void *mem_ctx, ir_rvalue *actual, const glsl_type *formal_type, ir_rvalue *lhs = actual; if (expr != NULL && expr->operation == ir_binop_vector_extract) { - rhs = new(mem_ctx) ir_expression(ir_triop_vector_insert, - expr->operands[0]->type, - expr->operands[0]->clone(mem_ctx, NULL), - rhs, - expr->operands[1]->clone(mem_ctx, NULL)); - lhs = expr->operands[0]->clone(mem_ctx, NULL); + lhs == new(mem_ctx) ir_dereference_array(expr->operands[0]->clone(mem_ctx, NULL), + expr->operands[1]->clone(mem_ctx, NULL)); } ir_assignment *const assignment_2 = new(mem_ctx) ir_assignment(lhs, rhs); |