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| author | Blue Swirl <blauwirbel@gmail.com> | 2009-05-10 18:23:46 +0000 |
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| committer | Blue Swirl <blauwirbel@gmail.com> | 2009-05-10 18:23:46 +0000 |
| commit | f0f26a06d51b7e7764f8951cdbf67ac9ad507f6d (patch) | |
| tree | 7bfbaea41b559a929c803cd67ef87ad9eb049bd3 /qemu-tech.texi | |
| parent | d084469ca0a0fb7c7f51dbe9062092c6983dfa02 (diff) | |
| download | qemu-f0f26a06d51b7e7764f8951cdbf67ac9ad507f6d.zip qemu-f0f26a06d51b7e7764f8951cdbf67ac9ad507f6d.tar.gz qemu-f0f26a06d51b7e7764f8951cdbf67ac9ad507f6d.tar.bz2 | |
Update docs on dynamic condition code calculation
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Diffstat (limited to 'qemu-tech.texi')
| -rw-r--r-- | qemu-tech.texi | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/qemu-tech.texi b/qemu-tech.texi index 6c24d91..ed2d35b 100644 --- a/qemu-tech.texi +++ b/qemu-tech.texi @@ -363,7 +363,9 @@ look at @code{tcg/README}. Lazy evaluation of CPU condition codes (@code{EFLAGS} register on x86) is important for CPUs where every instruction sets the condition codes. It tends to be less important on conventional RISC systems -where condition codes are only updated when explicitly requested. +where condition codes are only updated when explicitly requested. On +Sparc64, costly update of both 32 and 64 bit condition codes can be +avoided with lazy evaluation. Instead of computing the condition codes after each x86 instruction, QEMU just stores one operand (called @code{CC_SRC}), the result @@ -376,8 +378,8 @@ conditional branches. @code{CC_OP} is almost never explicitly set in the generated code because it is known at translation time. -The lazy condition code evaluation is used on x86, m68k and cris. ARM -uses a simplified variant for the N and Z flags. +The lazy condition code evaluation is used on x86, m68k, cris and +Sparc. ARM uses a simplified variant for the N and Z flags. @node CPU state optimisations @section CPU state optimisations |