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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-i386 | |
| parent | bf28a69eeb53e9e45166fbdda032454e7b1e3f29 (diff) | |
| download | qemu-c3ce5a235741cb027b1328288ddec06470254813.zip qemu-c3ce5a235741cb027b1328288ddec06470254813.tar.gz qemu-c3ce5a235741cb027b1328288ddec06470254813.tar.bz2 | |
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-i386')
| -rw-r--r-- | target-i386/cpu.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/target-i386/cpu.h b/target-i386/cpu.h index 1cb32ae..e645698 100644 --- a/target-i386/cpu.h +++ b/target-i386/cpu.h @@ -698,6 +698,13 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS]; /* Use a clearer name for this. */ #define CPU_INTERRUPT_INIT CPU_INTERRUPT_RESET +/* Instead of computing the condition codes after each x86 instruction, + * QEMU just stores one operand (called CC_SRC), the result + * (called CC_DST) 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. + */ typedef enum { CC_OP_DYNAMIC, /* must use dynamic code to get cc_op */ CC_OP_EFLAGS, /* all cc are explicitly computed, CC_SRC = flags */ |