ac/nir: port Z compare value clamping from radeonsi

This fixes some dEQP tests.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
index 7294b293ca247951418e266138c686c78fafd03b..b4b4e423a8ddfd2c9d384446e614a11df5d76acc 100644 (file)
--- a/src/amd/common/ac_nir_to_llvm.c
+++ b/src/amd/common/ac_nir_to_llvm.c
@@ -4019,8 +4019,10 @@ static void visit_tex(struct ac_nir_context *ctx, nir_tex_instr *instr)
                case nir_tex_src_projector:
                        break;
                case nir_tex_src_comparator:
-                       if (instr->is_shadow)
+                       if (instr->is_shadow) {
                                args.compare = get_src(ctx, instr->src[i].src);
+                               args.compare = ac_to_float(&ctx->ac, args.compare);
+                       }
                        break;
                case nir_tex_src_offset:
                        args.offset = get_src(ctx, instr->src[i].src);
@@ -4104,19 +4106,33 @@ static void visit_tex(struct ac_nir_context *ctx, nir_tex_instr *instr)
                args.offset = pack;
        }
 
-       /* 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 for GFX8-9; GFX10 has an explicitly
-        * clamped 32-bit float format.
+       /* Section 8.23.1 (Depth Texture Comparison Mode) of the
+        * OpenGL 4.5 spec says:
+        *
+        *    "If the texture’s internal format indicates a fixed-point
+        *     depth texture, then D_t and D_ref are clamped to the
+        *     range [0, 1]; otherwise no clamping is performed."
         *
-        * It's unnecessary if the original texture format was
-        * Z32_FLOAT, but we don't know that here.
+        * TC-compatible HTILE promotes Z16 and Z24 to Z32_FLOAT,
+        * so the depth comparison value isn't clamped for Z16 and
+        * Z24 anymore. Do it manually here for GFX8-9; GFX10 has
+        * an explicitly clamped 32-bit float format.
         */
        if (args.compare &&
            ctx->ac.chip_class >= GFX8 &&
            ctx->ac.chip_class <= GFX9 &&
-           ctx->abi->clamp_shadow_reference)
-               args.compare = ac_build_clamp(&ctx->ac, ac_to_float(&ctx->ac, args.compare));
+           ctx->abi->clamp_shadow_reference) {
+               LLVMValueRef upgraded, clamped;
+
+               upgraded = LLVMBuildExtractElement(ctx->ac.builder, args.sampler,
+                                                  LLVMConstInt(ctx->ac.i32, 3, false), "");
+               upgraded = LLVMBuildLShr(ctx->ac.builder, upgraded,
+                                        LLVMConstInt(ctx->ac.i32, 29, false), "");
+               upgraded = LLVMBuildTrunc(ctx->ac.builder, upgraded, ctx->ac.i1, "");
+               clamped = ac_build_clamp(&ctx->ac, args.compare);
+               args.compare = LLVMBuildSelect(ctx->ac.builder, upgraded, clamped,
+                                              args.compare, "");
+       }
 
        /* pack derivatives */
        if (ddx || ddy) {