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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
09158 Crash/Freeze Minor Always 10 days ago 10 days ago
Tester cuavas View Status Public Platform MAME (Self-compiled)
Assigned To Resolution Open OS Windows 10/11 (64-bit)
Status [?] Acknowledged Driver
Version 0.277 Fixed in Version Build 32-bit
Fixed in Git Commit Github Pull Request #
Summary 09158: bgfx video causes assertion failure on start when using x87 floating point
Description After updating ImGUI to 1.91.9b, using -video bgfx in a debug build using x87 floating point will result in the following assertion failure on start:

Assertion failed: dy >= 0, file ../../../../../3rdparty/bgfx/3rdparty/stb/stb_truetype.h, line 3160

This is presumably due to x87 floating point using 80-bit precision for intermediate results, and hence giving different results to other floating point units.

Osso was the biggest proponent of updating ImGUI, so perhaps he wants to look at it or report upstream to the ImGUI project?
Steps To Reproduce 1. Compile MAME with x87 floating point maths (e.g. a 32-bit i686 build without enabling SSE or using the -mfpmath=387 option with GCC).
2. Start any system with -video bgfx.
3. MAME fails to start with an assertion failure.
Additional Information
Github Commit
Flags
Regression Version 0.277
Affected Sets / Systems
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