ac/nir: Only clamp shadow reference on radeonsi.

Vulkan CTS does not expect the value to be clamped (at least for D32),
and it makes a differences even though depth is in [0,1], due
to strict inequalities.

I couldn't find anything in the Vulkan spec about this, but the test
seemed to be copied from GL tests and the GL spec only specifies
clamping for fixed point formats. Hence I expect radeonsi to run into
this at some point as well, but given that they still have a usecase
with the Z16->Z32 promotion, I'll leave that for someone else to clean
up.

This at least fixes radv dEQP-VK.texture.shadow.* on VI.

Fixes: 0f9e32519bb 'ac/nir: clamp shadow texture comparison value on VI'
Reviewed-by: Dave Airlie <airlied@redhat.com>

diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
index 5e5a46a21f473f88a4ed15969315096b43593365..2ddc748b5beec6c0bd24ce04f52eaf886ed12d89 100644 (file)
--- a/src/amd/common/ac_nir_to_llvm.c
+++ b/src/amd/common/ac_nir_to_llvm.c
@@ -4652,14 +4652,14 @@ static void visit_tex(struct ac_nir_context *ctx, nir_tex_instr *instr)
                LLVMValueRef z = ac_to_float(&ctx->ac,
                                             llvm_extract_elem(&ctx->ac, comparator, 0));
 
-               /* TC-compatible HTILE promotes Z16 and Z24 to Z32_FLOAT,
+               /* TC-compatible HTILE on radeonsi promotes Z16 and Z24 to Z32_FLOAT,
                 * so the depth comparison value isn't clamped for Z16 and
                 * Z24 anymore. Do it manually here.
                 *
                 * It's unnecessary if the original texture format was
                 * Z32_FLOAT, but we don't know that here.
                 */
-               if (ctx->ac.chip_class == VI)
+               if (ctx->ac.chip_class == VI && ctx->abi->clamp_shadow_reference)
                        z = ac_build_clamp(&ctx->ac, z);
 
                address[count++] = z;
@@ -6600,6 +6600,7 @@ LLVMModuleRef ac_translate_nir_to_llvm(LLVMTargetMachineRef tm,
        ctx.abi.emit_outputs = handle_shader_outputs_post;
        ctx.abi.load_ssbo = radv_load_ssbo;
        ctx.abi.load_sampler_desc = radv_get_sampler_desc;
+       ctx.abi.clamp_shadow_reference = false;
 
        if (shader_count >= 2)
                ac_init_exec_full_mask(&ctx.ac);

diff --git a/src/amd/common/ac_nir_to_llvm.h b/src/amd/common/ac_nir_to_llvm.h
index 9579aeeefef4abab15b05c736d6dee4919f652b9..1d9ec8ce8b01da597a995885724be8228670688f 100644 (file)
--- a/src/amd/common/ac_nir_to_llvm.h
+++ b/src/amd/common/ac_nir_to_llvm.h
@@ -80,6 +80,7 @@ struct ac_nir_compiler_options {
        struct ac_shader_variant_key key;
        bool unsafe_math;
        bool supports_spill;
+       bool clamp_shadow_reference;
        enum radeon_family family;
        enum chip_class chip_class;
 };

diff --git a/src/amd/common/ac_shader_abi.h b/src/amd/common/ac_shader_abi.h
index 5f296be0c1f07c88d574dec257926a2514a27c12..14517d5570042769cca4010ca174f79cbc92f0df 100644 (file)
--- a/src/amd/common/ac_shader_abi.h
+++ b/src/amd/common/ac_shader_abi.h
@@ -88,6 +88,10 @@ struct ac_shader_abi {
                                          LLVMValueRef index,
                                          enum ac_descriptor_type desc_type,
                                          bool image, bool write);
+
+       /* Whether to clamp the shadow reference value to [0,1]on VI. Radeonsi currently
+        * uses it due to promoting D16 to D32, but radv needs it off. */
+       bool clamp_shadow_reference;
 };
 
 #endif /* AC_SHADER_ABI_H */

diff --git a/src/gallium/drivers/radeonsi/si_shader_nir.c b/src/gallium/drivers/radeonsi/si_shader_nir.c
index a2d175364f833c403b23707042534c3c50883e69..e186661caf3b0054ba5e4941e26ed3e698fa4090 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_shader_nir.c
+++ b/src/gallium/drivers/radeonsi/si_shader_nir.c
@@ -498,6 +498,7 @@ bool si_nir_build_llvm(struct si_shader_context *ctx, struct nir_shader *nir)
 
        ctx->abi.inputs = &ctx->inputs[0];
        ctx->abi.load_sampler_desc = si_nir_load_sampler_desc;
+       ctx->abi.clamp_shadow_reference = true;
 
        ctx->num_samplers = util_last_bit(info->samplers_declared);
        ctx->num_images = util_last_bit(info->images_declared);