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25 * @file vc4_opt_small_immediates.c
27 * Turns references to small constant uniform values into small immediates
37 qir_opt_small_immediates(struct vc4_compile *c)
39 bool progress = false;
41 qir_for_each_inst_inorder(inst, c) {
42 /* The small immediate value sits in the raddr B field, so we
43 * can't have 2 small immediates in one instruction (unless
44 * they're the same value, but that should be optimized away
47 bool uses_small_imm = false;
48 for (int i = 0; i < qir_get_nsrc(inst); i++) {
49 if (inst->src[i].file == QFILE_SMALL_IMM)
50 uses_small_imm = true;
55 /* Don't propagate small immediates into the top-end bounds
56 * checking for indirect UBO loads. The kernel doesn't parse
57 * small immediates and rejects the shader in this case. UBO
58 * loads are much more expensive than the uniform load, and
59 * indirect UBO regions are usually much larger than a small
60 * immediate, so it's not worth updating the kernel to allow
63 if (inst->op == QOP_MIN_NOIMM)
66 for (int i = 0; i < qir_get_nsrc(inst); i++) {
67 struct qreg src = qir_follow_movs(c, inst->src[i]);
69 if (src.file != QFILE_UNIF ||
71 c->uniform_contents[src.index] !=
76 if (qir_is_tex(inst) &&
77 i == qir_get_tex_uniform_src(inst)) {
78 /* No turning the implicit uniform read into
84 uint32_t imm = c->uniform_data[src.index];
85 uint32_t small_imm = qpu_encode_small_immediate(imm);
90 fprintf(stderr, "opt_small_immediate() from: ");
91 qir_dump_inst(c, inst);
92 fprintf(stderr, "\n");
94 inst->src[i].file = QFILE_SMALL_IMM;
95 inst->src[i].index = imm;
97 fprintf(stderr, "to: ");
98 qir_dump_inst(c, inst);
99 fprintf(stderr, "\n");