We iteratively remove all dead Hydrogen instruction until we reach a fixed point. We consider an instruction dead if it is unused, has no observable side effects and is deletable. The last part of the condition is currently not very nice: We basically have to whitelist "safe" instructions, because we are missing more detailed dependencies and/or more detailed tracking of side effects.
We disable dead code elimination for now in our test runners, because we have tons of poorly written tests which wouldn't test anymore what they are supposed to test with this phase enabled. To get test coverage for dead code elimination itself, we should enable it on a few build bots. This is not really a perfect state, but the best we can do for now.
This patch includes a few const-correctness fixes, most of them were necessary for this CL.
Review URL: https://codereview.chromium.org/11088027
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12697 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Safe operations are those that either do not observe unsignedness or have special support for uint32 values:
- all binary bitwise operations: they perform ToInt32 on inputs;
- >> and << shifts: they perform ToInt32 on left hand side and ToUint32 on right hand side;
- >>> shift: it performs ToUint32 on both inputs;
- stores to integer external arrays (not pixel, float or double ones): these stores are "bitwise";
- HChange: special support added for conversions of uint32 values to double and tagged values;
- HSimulate: special support added for deoptimization with uint32 values in registers and stack slots;
- HPhi: phis that have only safe uses and only uint32 operands are uint32 themselves.
BUG=v8:2097
TEST=test/mjsunit/compiler/uint32.js
Review URL: https://chromiumcodereview.appspot.com/10778029
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12367 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Highlights of this CL:
* Introduced a new opcode in the deoptimizer for a setter stub frame.
* Added a global setter stub for returning after deoptimizing a setter.
* We do not need special deopt support for getters, although the getter stub creates an internal frame. The normal machinery works just right for this case, although we generate a stack that can never occur during normal fullcode execution. If this hurts us one day, we can parameterize and reuse the setter deopt machinery.
Review URL: https://chromiumcodereview.appspot.com/10855098
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12328 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
in anticipation of the upcoming lexical global scope.
Mostly automatised as:
for FILE in `egrep -ril "global[ _]?context" src test/cctest`
do
echo $FILE
sed "s/Global context/Native context/g" <$FILE >$FILE.0
sed "s/global context/native context/g" <$FILE.0 >$FILE.1
sed "s/global_context/native_context/g" <$FILE.1 >$FILE.2
sed "s/GLOBAL_CONTEXT/NATIVE_CONTEXT/g" <$FILE.2 >$FILE.3
sed "s/GlobalContext/NativeContext/g" <$FILE.3 >$FILE
rm $FILE.[0-9]
done
R=mstarzinger@chromium.org
BUG=
TEST=
Review URL: https://chromiumcodereview.appspot.com/10832342
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12325 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
regardless of the detected CPU. This is a requirement for the
debugger and the deoptimizer, which both expect that code from
the snapshot (compiled without VFP and ARM7) should have the
same layout as code compiled later.
This is another change to make snapshots more robust with
arbitrary code.
Review URL: https://chromiumcodereview.appspot.com/10824235
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12287 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This adds the --verify-global-context-separation flag which can be used
to verify that no code object embeds pointers to more than one global
context after a full GC. It uses an object visitor that just performs
shallow traversal of the object graph spanned by one code object, and
breaks at points where application objects are encountered. So it will
not trip on cross-context leaks introduced by the application itself.
R=verwaest@chromium.org
Review URL: https://chromiumcodereview.appspot.com/10830049
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12224 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Currently only simple getter calls are handled (i.e. no calls in count
operations or compound assignments), and deoptimization in the getter is not
handled at all. Because of the latter, we temporarily hide this feature behind a
new flag --inline-accessors, which is false by default.
Review URL: https://chromiumcodereview.appspot.com/10828066
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12223 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
with more JS code that is loaded into the VM before writing the snapshot. Get
rid of the hard coded limit on the partial snapshot cache size. This change
disables most of the serializer tests for the snapshot build of the VM: It's
getting too complicated to support both booting from a snapshot and then
creating a new snapshot from the same VM or loading more code with another
snapshot in the same VM.
Review URL: http://codereview.chromium.org/10574013
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11871 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
