fix: compute PF, ZF, SF after AAA and AAS instructions#2311
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huehuehuehueing wants to merge 1 commit intounicorn-engine:devfrom
Open
fix: compute PF, ZF, SF after AAA and AAS instructions#2311huehuehuehueing wants to merge 1 commit intounicorn-engine:devfrom
huehuehuehueing wants to merge 1 commit intounicorn-engine:devfrom
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helper_aaa and helper_aas only updated CF and AF in eflags, leaving PF, ZF, SF, and OF stale from the prior instruction. While Intel documents these flags as undefined after AAA/AAS, real x86 CPUs consistently set them based on the masked AL result. The sibling helpers helper_daa and helper_das in the same file already compute these flags correctly. This causes observable divergence when code branches on PF (e.g. JP/JNP) after AAA, which occurs in real-world binaries. The fix computes ZF, PF, SF from the result AL after AAA/AAS, using the same approach as DAA/DAS. Two regression tests verify the correct flag values. Signed-off-by: Larry H <l.gr@dartmouth.edu>
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Summary
helper_aaaandhelper_aasonly updated CF and AF, leaving PF, ZF, SF, and OF stale from the prior instructionhelper_daa/helper_dasin the same file already compute these flags correctlyFix
Compute ZF, PF, SF from result AL after AAA/AAS, using the same approach as DAA/DAS.
Test plan
test_x86_aaa_flags-- verifies PF, ZF, SF, CF after AAA with adjustmenttest_x86_aas_flags-- verifies PF, ZF, SF, CF after AAS with adjustment