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When you're trying to figure out what shader some NIR pass broke, use nir_shader_bisect_select() to decide between NIR pass behaviors, and then nir_shader_bisect.py will help you automatically bisect down to which source_blake3 is at fault. Once it's identified, it prints you a C call you can use for selecting that shader specifically, which you can use for continuing on in your debugging. On a test I was looking at, this took 10 steps to bisect 134 shaders down to the source_blake3 of the NIR shader in question. This idea is heavily lifted from Job Noorman's ir3_shader_bisect. Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37468>
73 lines
2.5 KiB
C
73 lines
2.5 KiB
C
#include "nir.h"
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#include "util/hex.h"
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#include "util/log.h"
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#include "util/mesa-blake3.h"
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#include "util/u_call_once.h"
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/** @file
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* Shader bisect support.
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*
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* Simply use nir_shader_bisect_select() to control some bad behavior you've
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* identified (calling a shader pass or executing some bad part of a
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* shader_pass), then run your application under nir_shader_bisect.py to be
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* interactively guided through bisecting down to which NIR shader in your
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* program is being badly affected by the code in question.
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*
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* Note that doing this requires (unless someone rigs up cache key handling)
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* MESA_SHADER_DISABLE_CACHE=1, which is also set by nir_shader_bisect.py.
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*/
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/* These are expected to be hex dumps of blake3 bytes, no space and no leading
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* '0x'
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*/
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static const char *nir_shader_bisect_lo = NULL;
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static const char *nir_shader_bisect_hi = NULL;
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DEBUG_GET_ONCE_OPTION(nir_shader_bisect_lo, "NIR_SHADER_BISECT_LO", NULL);
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DEBUG_GET_ONCE_OPTION(nir_shader_bisect_hi, "NIR_SHADER_BISECT_HI", NULL);
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static void
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nir_shader_bisect_init(void)
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{
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nir_shader_bisect_lo = debug_get_option_nir_shader_bisect_lo();
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nir_shader_bisect_hi = debug_get_option_nir_shader_bisect_hi();
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if (nir_shader_bisect_lo)
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assert(strlen(nir_shader_bisect_lo) + 1 == BLAKE3_HEX_LEN);
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if (nir_shader_bisect_hi)
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assert(strlen(nir_shader_bisect_hi) + 1 == BLAKE3_HEX_LEN);
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}
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bool
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nir_shader_bisect_select(nir_shader *s)
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{
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static once_flag once = ONCE_FLAG_INIT;
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call_once(&once, nir_shader_bisect_init);
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if (!nir_shader_bisect_lo && !nir_shader_bisect_hi)
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return false;
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char id[BLAKE3_HEX_LEN];
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_mesa_blake3_format(id, s->info.source_blake3);
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if (nir_shader_bisect_lo && strcmp(id, nir_shader_bisect_lo) < 0)
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return false;
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if (nir_shader_bisect_hi && strcmp(id, nir_shader_bisect_hi) > 0)
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return false;
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uint32_t u32[BLAKE3_OUT_LEN32] = { 0 };
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for (unsigned i = 0; i < BLAKE3_OUT_LEN; i++)
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u32[i / 4] |= (uint32_t)s->info.source_blake3[i] << ((i % 4) * 8);
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/* Provide feedback of both the source_blake3 and the blake3_format id to the
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* script of what shaders got affected, so it can bisect on the set of
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* shaders remaining for the env vars, and print out a final blake3 when we
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* get down to 1 shader.
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*/
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mesa_logi("NIR bisect selected source_blake3: {0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x} (%s)\n",
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u32[0], u32[1], u32[2], u32[3],
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u32[4], u32[5], u32[6], u32[7], id);
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return true;
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}
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