context. Test contexts are used for the left subexpressions of
short-circuited boolean operators. The right subexpressions inherit
their expression context from the binary op expression.
Compilation of short-circuited operations in effect and test context
is straightforward:
effect(e0 || e1) =
test(e0, L0, L1)
L1: effect(e1)
L0:
test(e0 || e1, L0, L1) =
test(e0, L0, L2)
L2: test(e1, L0, L1)
Because the value of the first subexpression may be needed as the
value of the whole expression in a value context, we introduce a
hybrid value/test contest (the value is needed if true, but not if
false).
value(e0 || e1) =
value/test(e0, L0, L1)
L1: value(e1)
L0:
The compilation of value/test and test/value (introduced by boolean
AND) is:
value/test(e0 || e1, L0, L1) =
value/test(e0, L0, L2)
L2: value/test(e1, L0, L1)
test/value(e0 || e1, L0, L1) =
test(e0, L0, L2)
L2: test/value(e1, L0, L1)
Boolean AND is the dual. The AST nodes themselves (not their parents)
are responsible for producing the proper result (effect, value, or
control flow) depending on their context.
Review URL: http://codereview.chromium.org/339082
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3187 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
o.x() and o[expr]()
other changes:
- Fix missing relocation info for StoreIC on global object.
- Generate only one common return sequence instead of always appending
"return <undefined>" at the end of each function: The first JS
return-statement will generate the common return sequence. All
other return-statements will generate a unconditional branch to the common
return sequence.
Review URL: http://codereview.chromium.org/340037
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3183 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
The code for .result = (b.y = 99) where b is a global variable is:
push [esi+0x17]
mov ecx,0xf5c229ad ;; object: 0xf5c229ad <String[1]: b>
call LoadIC_Initialize
nop
mov [esp],eax
mov eax,0xc6
mov ecx,0xf5c25c41 ;; object: 0xf5c25c41 <String[1]: y>
call StoreIC_Initialize
nop
mov [esp],eax
pop [ebp+0xf4]
There is still some room for improvement in the generated code.
Other changes:
- Replaced switch-statement in FastCodeGenerator::VisitProperty with DropAndMove(...)
- Do not emit nop after IC calls on ARM.
Review URL: http://codereview.chromium.org/347001
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3180 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
context of the expressions they label. Introduce an "unintialized"
location to catch failure to assign any location at all.
Changed the object literal initialization on ARM to use a Store IC in
the same cases where it did on the other platforms. This was required
because the location of the literal property name is given an
"unitialized" location.
Review URL: http://codereview.chromium.org/339045
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3171 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
location to an Expression AST node from the node's parent to the node
itself.
This allows an inherited code generation context from a parent node to
be passed arbitrarily far down the tree (eg, the subexpression of a
unary not is in the same context as the unary expression itself, the
then and else subexpressions of the ternary operator are in the same
context as the whole expression, and so forth).
We do not yet take advantage of this in the backend (eg, the right
subexpression of short-circuited OR is still compiled by using the
parent's destination location, rather than the subexpression's
itself).
Review URL: http://codereview.chromium.org/340005
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3163 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Literals now have a location of temporary by default and are
responsible for moving themselves into their location like all other
expressions.
The constant location turned out not to allow us to avoid checking
subexpressions in AST interior nodes, and it turned out to require
checking after some normal calls to Visit (like for the arguments to a
call). With this change do not have to check after a call to Visit
that we got our result in the expected location.
Review URL: http://codereview.chromium.org/339004
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3137 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
I also added more unit tests for literals.
Right now, the fast compiler produces code very similar to
the existing code generator. We may consider different ways to
further compact the generated code for top-level code.
ARM always goes through a runtime function to initialize computed
properties in an object literal whereas IA32 and x64 use StoreIC.
Review URL: http://codereview.chromium.org/316009
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3129 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
in a non-test (ie, value or effect) context. (It is implicitly not in
a test context because the code generator does not support expressions
in a test context yet.)
Compilation is essentially the same as in the optimized code
generator. The expression (e0 || e1) is compiled as if it were
(let (temp = e0) temp ? temp : e1).
On ia32 and x64 a single shared ToBoolean stub is used to convert a
value to a flag. The inlined checks assumed by the stub are reordered
to compare to undefined (the common case in toplevel code?) first. On
ARM a call to the runtime is used. In the interest of code size no
checks are yet inlined on ARM.
Review URL: http://codereview.chromium.org/334006
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3118 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
currently compiled the same as with the optimizing compiler: they are
cloned from a boilerplate object and the boilerplate objects are
lazily constructed.
Also changed argument pushing on ARM to use stm (store multiple),
which required changing the order of arguments to the runtime
functions DeclareGlobals and NewClosure. They were only used from
generated code.
Finally, changed the toplevel code generator so that stack pops to
discard a temporary became addition to the stack pointer on ia32 and
x64.
Review URL: http://codereview.chromium.org/303021
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3110 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
For .result = /abc.*/g we generate the following IA-32 code:
...
mov ebx,[edi+0x17]
mov eax,[ebx+0xb]
cmp eax, 0xf5d0e135 ;; object: 0xf5d0e135 <undefined>
jnz done
push ebx
push 0x2
push 0xf5d13805 ;; object: 0xf5d13805 <String[5]: abc.*>
push 0xf5d13815 ;; object: 0xf5d13815 <String[1]: g>
call RuntimeStub_MaterializeRegExpLiteral
done:
push eax
pop [ebp+0xf4]
...
This is very similar to the code previously generated except we do not
generate deferred code for the case where we call the runtime.
On ARM we use the stm instruction to make pushing the arguments more compact.
Review URL: http://codereview.chromium.org/300037
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3109 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
constant known at compile time. Do not ever use the stack to
materialize (non-function-argument) constants. Currently, constants
are only the non-materialized, non-function literals in the AST.
It is a known issue that there is no test coverage for the cases of
assigning a non-literal to a variable and returning a literal. Those
code paths are unreachable and tests will be added when they become
reachable.
For the code '.result = true', we had previously on ia32:
27 push 0xf5c28161 ;; object: 0xf5c28161 <true>
32 pop [ebp+0xf4]
Now:
27 mov eax,0xf5c26161 ;; object: 0xf5c26161 <true>
32 mov [ebp+0xf4],eax
======== We had previously on x64:
25 movq r10,0x7fb8c2f78199 ;; object: 0x7fb8c2f78199 <true>
35 push r10
37 pop [rbp-0x18]
Now:
25 movq r10,0x7fb131386199 ;; object: 0x7fb131386199 <true>
35 movq [rbp-0x18],r10
The generated code for ARM did not include the extra memory traffic.
It was already eliminated by the ARM assembler's push/pop elimination.
Review URL: http://codereview.chromium.org/300003
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3088 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Slots appear only indirectly in the AST (through variables linked to
variable proxies). Slots are shared among variable references, so
putting compilation-time state on them is potentially a source of
bugs. Avoid it for now.
Review URL: http://codereview.chromium.org/284009
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3079 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
fast-mode code generator.
AST expression nodes are annotated with a location when doing the
initial syntactic check of the AST. In the current implementation,
expression locations are 'temporary' (ie, allocated to the stack) or
'nowhere' (ie, the expression's value is not needed though it must be
evaluated for side effects).
For the assignment '.result = true' on IA32, we had before (with the
true value already on top of the stack):
32 mov eax,[esp]
35 mov [ebp+0xf4],eax
38 pop eax
Now:
32 pop [ebp+0xf4]
======== On x64, before:
37 movq rax,[rsp]
41 movq [rbp-0x18],rax
45 pop rax
Now:
37 pop [rbp-0x18]
======== On ARM, before (with the true value in register ip):
36 str ip, [sp, #-4]!
40 ldr ip, [sp, #+0]
44 str ip, [fp, #-12]
48 add sp, sp, #4
Now:
36 str ip, [fp, #-12]
Review URL: http://codereview.chromium.org/267118
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3076 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
