From 1e29f57b3ac4ec6560d0d355576be3cd784cf131 Mon Sep 17 00:00:00 2001 From: Alyssa Rosenzweig Date: Tue, 27 Jul 2021 18:34:35 -0400 Subject: [PATCH] pan/bi: Validate the live set starts empty Otherwise there is an uninitialized read, and the register allocation will fail. (In the sense of failing a precondition. This manifests as synthetic interference leading to higher register pressure and useless moves. The allocation itself is ok, but it indicates a real bug.) Signed-off-by: Alyssa Rosenzweig Part-of: --- src/panfrost/bifrost/bi_validate.c | 78 ++++++++++++++++++++++++++ src/panfrost/bifrost/bifrost.h | 1 + src/panfrost/bifrost/bifrost_compile.c | 6 ++ src/panfrost/bifrost/compiler.h | 8 +++ src/panfrost/bifrost/meson.build | 1 + 5 files changed, 94 insertions(+) create mode 100644 src/panfrost/bifrost/bi_validate.c diff --git a/src/panfrost/bifrost/bi_validate.c b/src/panfrost/bifrost/bi_validate.c new file mode 100644 index 00000000000..d6eab037543 --- /dev/null +++ b/src/panfrost/bifrost/bi_validate.c @@ -0,0 +1,78 @@ +/* + * Copyright (C) 2021 Collabora, Ltd. + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#include "compiler.h" +#include "util/u_memory.h" + +/* Validatation doesn't make sense in release builds */ +#ifndef NDEBUG + +/* Validate that all sources are initialized in all read components. This is + * required for correct register allocation. We check a weaker condition, that + * all sources that are read are written at some point (equivalently, the live + * set is empty at the start of the program). TODO: Strengthen */ + +bool +bi_validate_initialization(bi_context *ctx) +{ + bool success = true; + + /* Calculate the live set */ + bi_block *entry = bi_entry_block(ctx); + unsigned temp_count = bi_max_temp(ctx); + bi_invalidate_liveness(ctx); + bi_compute_liveness(ctx); + + /* Validate that the live set is indeed empty */ + for (unsigned i = 0; i < temp_count; ++i) { + if (entry->live_in[i] == 0) continue; + + fprintf(stderr, "%s%u\n", (i & PAN_IS_REG) ? "r" : "", i >> 1); + success = false; + } + + return success; +} + +void +bi_validate(bi_context *ctx, const char *after) +{ + bool fail = false; + + if (bifrost_debug & BIFROST_DBG_NOVALIDATE) + return; + + if (!bi_validate_initialization(ctx)) { + fprintf(stderr, "Uninitialized data read after %s\n", after); + fail = true; + } + + /* TODO: Validate more invariants */ + + if (fail) { + bi_print_shader(ctx, stderr); + exit(1); + } +} + +#endif /* NDEBUG */ diff --git a/src/panfrost/bifrost/bifrost.h b/src/panfrost/bifrost/bifrost.h index 436404f0be0..74b110f204c 100644 --- a/src/panfrost/bifrost/bifrost.h +++ b/src/panfrost/bifrost/bifrost.h @@ -37,6 +37,7 @@ #define BIFROST_DBG_INTERNAL 0x0010 #define BIFROST_DBG_NOSCHED 0x0020 #define BIFROST_DBG_INORDER 0x0040 +#define BIFROST_DBG_NOVALIDATE 0x0080 extern int bifrost_debug; diff --git a/src/panfrost/bifrost/bifrost_compile.c b/src/panfrost/bifrost/bifrost_compile.c index cc6bb8741fb..afacef28831 100644 --- a/src/panfrost/bifrost/bifrost_compile.c +++ b/src/panfrost/bifrost/bifrost_compile.c @@ -45,6 +45,7 @@ static const struct debug_named_value bifrost_debug_options[] = { {"internal", BIFROST_DBG_INTERNAL, "Dump even internal shaders"}, {"nosched", BIFROST_DBG_NOSCHED, "Force trivial bundling"}, {"inorder", BIFROST_DBG_INORDER, "Force in-order bundling"}, + {"novalidate",BIFROST_DBG_NOVALIDATE, "Skip IR validation"}, DEBUG_NAMED_VALUE_END }; @@ -3659,6 +3660,8 @@ bifrost_compile_shader_nir(nir_shader *nir, block->name = block_source_count++; } + bi_validate(ctx, "NIR -> BIR"); + /* If the shader doesn't write any colour or depth outputs, it may * still need an ATEST at the very end! */ bool need_dummy_atest = @@ -3674,6 +3677,7 @@ bifrost_compile_shader_nir(nir_shader *nir, /* Runs before constant folding */ bi_lower_swizzle(ctx); + bi_validate(ctx, "Early lowering"); /* Runs before copy prop */ bi_opt_push_ubo(ctx); @@ -3685,6 +3689,7 @@ bifrost_compile_shader_nir(nir_shader *nir, bi_opt_dead_code_eliminate(ctx); bi_opt_cse(ctx); bi_opt_dead_code_eliminate(ctx); + bi_validate(ctx, "Optimization passes"); bi_foreach_block(ctx, block) { bi_lower_branch(block); @@ -3698,6 +3703,7 @@ bifrost_compile_shader_nir(nir_shader *nir, * skip bit is a function of only the data flow graph and is invariant * under valid scheduling. */ bi_analyze_helper_requirements(ctx); + bi_validate(ctx, "Late lowering"); bi_register_allocate(ctx); bi_opt_post_ra(ctx); diff --git a/src/panfrost/bifrost/compiler.h b/src/panfrost/bifrost/compiler.h index b1d50cc7945..311c99a2730 100644 --- a/src/panfrost/bifrost/compiler.h +++ b/src/panfrost/bifrost/compiler.h @@ -910,6 +910,14 @@ bool bi_reads_zero(bi_instr *ins); bool bi_reads_temps(bi_instr *ins, unsigned src); bool bi_reads_t(bi_instr *ins, unsigned src); +#ifndef NDEBUG +bool bi_validate_initialization(bi_context *ctx); +void bi_validate(bi_context *ctx, const char *after_str); +#else +static inline bool bi_validate_initialization(UNUSED bi_context *ctx) { return true; } +static inline void bi_validate(UNUSED bi_context *ctx, UNUSED const char *after_str) { return; } +#endif + uint32_t bi_fold_constant(bi_instr *I, bool *unsupported); void bi_opt_constant_fold(bi_context *ctx); diff --git a/src/panfrost/bifrost/meson.build b/src/panfrost/bifrost/meson.build index e18d5a57239..38f15391f45 100644 --- a/src/panfrost/bifrost/meson.build +++ b/src/panfrost/bifrost/meson.build @@ -38,6 +38,7 @@ libpanfrost_bifrost_files = files( 'bi_ra.c', 'bi_schedule.c', 'bi_scoreboard.c', + 'bi_validate.c', 'bir.c', 'bifrost_compile.c', )