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| author | Paolo Bonzini <pbonzini@redhat.com> | 2016-10-06 15:10:57 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-10-07 10:05:22 +0200 |
| commit | c3ce5a235741cb027b1328288ddec06470254813 (patch) | |
| tree | 18b91ded381a74e17158c282dea2047b0ae3c3e6 /target-m68k | |
| parent | bf28a69eeb53e9e45166fbdda032454e7b1e3f29 (diff) | |
| download | qemu-c3ce5a235741cb027b1328288ddec06470254813.tar.gz qemu-c3ce5a235741cb027b1328288ddec06470254813.tar.bz2 qemu-c3ce5a235741cb027b1328288ddec06470254813.zip | |
qemu-tech: document lazy condition code evaluation in cpu.h
Unlike the other sections, they are pretty specific to a particular CPU.
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'target-m68k')
| -rw-r--r-- | target-m68k/cpu.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/target-m68k/cpu.h b/target-m68k/cpu.h index c2d40cb1cc..471f490dc1 100644 --- a/target-m68k/cpu.h +++ b/target-m68k/cpu.h @@ -154,6 +154,14 @@ int cpu_m68k_signal_handler(int host_signum, void *pinfo, void *puc); void cpu_m68k_flush_flags(CPUM68KState *, int); + +/* Instead of computing the condition codes after each m68k instruction, + * QEMU just stores one operand (called CC_SRC), the result + * (called CC_DEST) and the type of operation (called CC_OP). When the + * condition codes are needed, the condition codes can be calculated + * using this information. Condition codes are not generated if they + * are only needed for conditional branches. + */ enum { CC_OP_DYNAMIC, /* Use env->cc_op */ CC_OP_FLAGS, /* CC_DEST = CVZN, CC_SRC = unused */ |