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gallivm/nir: Don't do uniform-and-broadcast access on inactive invocations.

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In a fragment shader or inside of control flow, invocation 0 might be
inactive, and so our use-first-invocation-and-broadcast optimizations
would be invalid, and the loop logic of an emit_read_invocation would
defeat the point of these optimized paths.

For load_kernel_input, I didn't guard the uniform path with the check
because some CL tests that are currently passing are doing the
load_kernel_input under (presumably) uniform control flow.  Instead, I
dropped in a once warning for the next person to be debugging CL.

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14999>
This commit is contained in:
Emma Anholt 2022-02-11 09:12:10 -08:00 • committed by Marge Bot
parent 04cdd41fdc
commit 9ab4ecb1ae
1 changed files with 26 additions and 1 deletions
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27
src/gallium/auxiliary/gallivm/lp_bld_nir_soa.c
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@ -70,6 +70,27 @@ mask_vec(struct lp_build_nir_context *bld_base)
exec_mask->exec_mask, "");
}
static bool
invocation_0_must_be_active(struct lp_build_nir_context *bld_base)
{
struct lp_build_nir_soa_context * bld = (struct lp_build_nir_soa_context *)bld_base;
/* Fragment shaders may dispatch with invocation 0 inactive. All other
* stages have invocation 0 active at the top. (See
* lp_build_tgsi_params.mask setup in draw_llvm.c and lp_state_*.c)
*/
if (bld_base->shader->info.stage == MESA_SHADER_FRAGMENT)
return false;
/* If we're in some control flow right now, then invocation 0 may be
* disabled.
*/
if (bld->exec_mask.has_mask)
return false;
return true;
}
static LLVMValueRef
emit_fetch_64bit(
struct lp_build_nir_context * bld_base,
@ -740,6 +761,10 @@ static void emit_load_kernel_arg(struct lp_build_nir_context *bld_base,
LLVMTypeRef ptr_type = LLVMPointerType(bld_broad->elem_type, 0);
kernel_args_ptr = LLVMBuildBitCast(builder, kernel_args_ptr, ptr_type, "");
if (!invocation_0_must_be_active(bld_base)) {
mesa_logw_once("Treating load_kernel_arg in control flow as uniform, results may be incorrect.");
}
if (offset_is_uniform) {
offset = LLVMBuildExtractElement(builder, offset, lp_build_const_int32(gallivm, 0), "");
@ -998,7 +1023,7 @@ static void emit_load_ubo(struct lp_build_nir_context *bld_base,
LLVMTypeRef ptr_type = LLVMPointerType(bld_broad->elem_type, 0);
consts_ptr = LLVMBuildBitCast(builder, consts_ptr, ptr_type, "");
if (offset_is_uniform) {
if (offset_is_uniform && invocation_0_must_be_active(bld_base)) {
offset = LLVMBuildExtractElement(builder, offset, lp_build_const_int32(gallivm, 0), "");
for (unsigned c = 0; c < nc; c++) {