glsl: Rebuild the symbol table without unreachable symbols

Graphics / Mesa 3D Graphics Library / Mesa - Ian Romanick [intel.com] - 4 August 2014 17:48 UTC

Previously we had to keep unreachable global symbols in the symbol table because the symbol table is used during linking. Having the symbol table retain pointers to freed memory... what could possibly go wrong? At the same time, this meant that we kept live references to tons of memory that was no longer needed.

New strategy: destroy the old symbol table, and make a new one from the reachable symbols.

Valgrind massif results for a trimmed apitrace of dota2:

n time(i) total(B) useful-heap(B) extra-heap(B) stacks(B) Before (32-bit): 59 40,642,425,451 76,337,968 69,720,886 6,617,082 0 After (32-bit): 46 40,661,487,174 75,116,800 68,854,065 6,262,735 0

Before (64-bit): 79 37,179,441,771 106,986,512 98,112,095 8,874,417 0 After (64-bit): 64 37,200,329,700 104,872,672 96,514,546 8,358,126 0

A real savings of 846KiB on 32-bit and 1.5MiB on 64-bit.

v2: (by Kenneth Graunke) Just add the ir_function from the IR stream, rather than looking it up in the symbol table; they're now identical.

7b18983 glsl: Rebuild the symbol table without unreachable symbols
src/glsl/glsl_parser_extras.cpp | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)

Upstream: cgit.freedesktop.org

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