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authorChristian Krinitsin <mail@krinitsin.com>2025-07-03 19:39:53 +0200
committerChristian Krinitsin <mail@krinitsin.com>2025-07-03 19:39:53 +0200
commitdee4dcba78baf712cab403d47d9db319ab7f95d6 (patch)
tree418478faf06786701a56268672f73d6b0b4eb239 /results/classifier/semantic-bugs/1901
parent4d9e26c0333abd39bdbd039dcdb30ed429c475ba (diff)
downloademulator-bug-study-dee4dcba78baf712cab403d47d9db319ab7f95d6.tar.gz
emulator-bug-study-dee4dcba78baf712cab403d47d9db319ab7f95d6.zip
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+instruction: 0.968
+graphic: 0.871
+device: 0.723
+semantic: 0.696
+other: 0.517
+network: 0.432
+socket: 0.404
+vnc: 0.392
+mistranslation: 0.243
+boot: 0.231
+assembly: 0.079
+KVM: 0.079
+
+qemu-sparc64 / sparc32plus apparent wrong results from VIS fmul8x16 instruction
+Description of problem:
+Experimenting with SPARC emulation, I noticed that the results of the UltraSparc fmul8x16 instruction don't appear to match the behaviour of real silicon (aka it doesn't appear to work at all -- in the test program, the result seems to be always 0).  Other VIS instructions I tried seem to be OK (I have not tried all of them).
+
+The same problem is observed both in 64-bit (qemu-sparc64) and 32-bit (qemu-sparc32plus) applications.
+Steps to reproduce:
+1. Compile the attached test program (which exhaustively tests all possible combinations of 16-bit and 8-bit inputs) with gcc:
+   ```
+   sparc64-unknown-linux-gnu-gcc -static -Os -mcpu=ultrasparc -mvis -o test_fmul8x16 test_fmul8x16.c
+   ```
+2. Run it in qemu-sparc64:
+   ```
+   qemu-sparc64 -cpu 'TI UltraSparc II' ./test_fmul8x16
+   ```
+3. Observe almost all tests fail.
+
+   Running the exact same compiled binary on a real UltraSparc II CPU gives all pass results.
+Additional information:
+[test_fmul8x16.c](/uploads/2bf68e53652fba2ed69ac3ebb3f4b5e9/test_fmul8x16.c)