Compiled C Equivalence Fixture

Compiled workload catalogue · Fidelity equivalence

Purpose

Check that compiler-generated stack, call/return, load/store, branch, and wraparound behavior matches between the reference datapath and compact model of each core.

Setup

Property	Value
Source/image	tests/fixtures/rv32i/differential/compiled.c and compiled.elf
Compiler	Pinned GCC 16.1.0, RV32I/ilp32, -O2, no linker relaxation
Input	Four volatile unsigned words: 7, 0xffffffff, 0x80000000, 0x5a5a5a5a
Startup	Shared bare-metal stack/main/tohost bridge
Verification	Full completion, not a prefix

Implementation

unsigned result = 0;
for (unsigned value : values) {
    if (value & 1) result += value;
    else result ^= value;
}
return result;

The actual C uses a non-inlined function and volatile array accesses. This simplified loop describes its behavior; the checked-in disassembly records the real generated instructions.

Expected result

Step	Input	Operation	Accumulator
1	0x00000007	Add odd value	0x00000007
2	0xffffffff	Add with 32-bit wraparound	0x00000006
3	0x80000000	XOR even value	0x80000006
4	0x5a5a5a5a	XOR even value	0xda5a5a5c

main returns zero only for this result. Startup converts success to tohost=1 and failure to 3. The test additionally compares settled cycle traces and final signatures, not only that verdict.

Running and rebuilding

build/rv32i_experiment --core advanced \
  --elf tests/fixtures/rv32i/differential/compiled.elf \
  --period 4000 --allocation-limit-mib 512 --max-cycles 1024
bash tools/rv32i-benchmarks/build-equivalence.sh

Rebuilding is optional for ordinary tests. The script uses one CPU and 512 MiB; update the ELF, disassembly, and SHA-256 together if source or compiler changes. This project-owned fixture is not an Embench program.

Source and tests

RV32IDifferentialTest runs the complete image on single-cycle, baseline, and advanced cores in both profiles: three paired cases. The equivalence reference describes what is compared and what is deliberately ignored.