[clr-interp] Fix conversion from unsigned integer to float #122369
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- There isn't a single instruction for this, but the jit recognizes the conv.r.un + conv.r4 pattern as meaning convert directly from unsigned integer to float. Per ECMA it is valid to do processing at a higher intermediate precision, but RyuJit/interpreter follows tighter rules which result in more less loss of precision.
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Pull request overview
This PR fixes the conversion from unsigned integers to float (R4) in the CLR interpreter. The JIT recognizes the conv.r.un + conv.r4 pattern as a direct unsigned-to-float conversion, and the interpreter now properly implements this pattern with distinct opcodes for R4 (float) versus R8 (double) conversions.
- Renamed existing
INTOP_CONV_R_UN_*opcodes toINTOP_CONV_R8_UN_*to clarify they convert to double - Added new
INTOP_CONV_R4_UN_*opcodes for direct unsigned-to-float conversion - Implemented a peephole optimization to recognize and properly handle the
conv.r.un + conv.r4pattern
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| src/coreclr/interpreter/inc/intops.def | Renamed CONV_R_UN opcodes to CONV_R8_UN for clarity and added new CONV_R4_UN opcodes for unsigned-to-float conversions |
| src/coreclr/vm/interpexec.cpp | Updated case labels to use renamed R8 opcodes and added execution logic for new R4 unsigned conversion opcodes |
| src/coreclr/interpreter/compiler.h | Added declarations for the new ConvRUnR4 peephole optimization methods |
| src/coreclr/interpreter/compiler.cpp | Implemented ConvRUnR4 peephole to recognize conv.r.un + conv.r4 pattern, updated Peeps array size, and updated opcode references to use renamed CONV_R8_UN opcodes |
This was referenced Dec 10, 2025
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Fixes Runtime_106338 test.