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authoraurel32 <aurel32@c046a42c-6fe2-441c-8c8c-71466251a162>2008-12-07 15:21:23 +0000
committeraurel32 <aurel32@c046a42c-6fe2-441c-8c8c-71466251a162>2008-12-07 15:21:23 +0000
commit86e840eef78d5c6882cfd2befd8571e6cd98782f (patch)
treea621a817d8e00349959d65a526a6f0ff2b0c4ce7 /tcg/README
parent955a7dd5e857bdeb1d41893a5ac9c1e02c327382 (diff)
downloadqemu-86e840eef78d5c6882cfd2befd8571e6cd98782f.tar.gz
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Remove a few dyngen and dyngen related code
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5914 c046a42c-6fe2-441c-8c8c-71466251a162
Diffstat (limited to 'tcg/README')
-rw-r--r--tcg/README21
1 files changed, 4 insertions, 17 deletions
diff --git a/tcg/README b/tcg/README
index bdb44dfd3b..fcdb6014b3 100644
--- a/tcg/README
+++ b/tcg/README
@@ -60,9 +60,8 @@ add_i32 t0, t1, t2 (t0 <- t1 + t2)
- Basic blocks end after branches (e.g. brcond_i32 instruction),
goto_tb and exit_tb instructions.
-- Basic blocks end before legacy dyngen operations.
-- Basic blocks start after the end of a previous basic block, at a
- set_label instruction or after a legacy dyngen operation.
+- Basic blocks start after the end of a previous basic block, or at a
+ set_label instruction.
After the end of a basic block, the content of temporaries is
destroyed, but local temporaries and globals are preserved.
@@ -423,18 +422,7 @@ register.
target, functions must be able to return 2 values in registers for
64 bit return type.
-5) Migration from dyngen to TCG
-
-TCG is backward compatible with QEMU "dyngen" operations. It means
-that TCG instructions can be freely mixed with dyngen operations. It
-is expected that QEMU targets will be progressively fully converted to
-TCG. Once a target is fully converted to TCG, it will be possible
-to apply more optimizations because more registers will be free for
-the generated code.
-
-The exception model is the same as the dyngen one.
-
-6) Recommended coding rules for best performance
+5) Recommended coding rules for best performance
- Use globals to represent the parts of the QEMU CPU state which are
often modified, e.g. the integer registers and the condition
@@ -442,8 +430,7 @@ The exception model is the same as the dyngen one.
- Avoid globals stored in fixed registers. They must be used only to
store the pointer to the CPU state and possibly to store a pointer
- to a register window. The other uses are to ensure backward
- compatibility with dyngen during the porting a new target to TCG.
+ to a register window.
- Use temporaries. Use local temporaries only when really needed,
e.g. when you need to use a value after a jump. Local temporaries