AuroraMiddleware/v8
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Landing for Justin Schuh.

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This switches out the existing constant splitting with masking that works like this:

1. Generate a random 32-bit value at compilation time.
2. XOR the 32-bit constant with the random value.
3. Emit the resulting immediate value along with the XOR operation to generate the original value.


BUG=http://code.google.com/p/v8/issues/detail?id=908

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5734 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
ager@chromium.org 2010-10-29 06:15:34 +00:00
parent 08fbd012b0
commit 46951e659c
3 changed files with 16 additions and 7 deletions
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3
src/flag-definitions.h
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@ -140,6 +140,9 @@ DEFINE_bool(stack_trace_on_abort, true,
// codegen-ia32.cc / codegen-arm.cc
DEFINE_bool(trace, false, "trace function calls")
DEFINE_bool(defer_negation, true, "defer negation operation")
DEFINE_bool(mask_constants_with_cookie,
true,
"use random jit cookie to mask large constants")
// codegen.cc
DEFINE_bool(lazy, true, "use lazy compilation")

15
src/ia32/codegen-ia32.cc
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@ -153,7 +153,8 @@ CodeGenerator::CodeGenerator(MacroAssembler* masm)
in_safe_int32_mode_(false),
safe_int32_mode_enabled_(true),
function_return_is_shadowed_(false),
in_spilled_code_(false) {
in_spilled_code_(false),
jit_cookie_((FLAG_mask_constants_with_cookie) ? V8::Random() : 0) {
}
@ -5363,16 +5364,16 @@ void CodeGenerator::VisitLiteral(Literal* node) {
void CodeGenerator::PushUnsafeSmi(Handle<Object> value) {
ASSERT(value->IsSmi());
int bits = reinterpret_cast<int>(*value);
__ push(Immediate(bits & 0x0000FFFF));
__ or_(Operand(esp, 0), Immediate(bits & 0xFFFF0000));
__ push(Immediate(bits ^ jit_cookie_));
__ xor_(Operand(esp, 0), Immediate(jit_cookie_));
}
void CodeGenerator::StoreUnsafeSmiToLocal(int offset, Handle<Object> value) {
ASSERT(value->IsSmi());
int bits = reinterpret_cast<int>(*value);
__ mov(Operand(ebp, offset), Immediate(bits & 0x0000FFFF));
__ or_(Operand(ebp, offset), Immediate(bits & 0xFFFF0000));
__ mov(Operand(ebp, offset), Immediate(bits ^ jit_cookie_));
__ xor_(Operand(ebp, offset), Immediate(jit_cookie_));
}
@ -5380,8 +5381,8 @@ void CodeGenerator::MoveUnsafeSmi(Register target, Handle<Object> value) {
ASSERT(target.is_valid());
ASSERT(value->IsSmi());
int bits = reinterpret_cast<int>(*value);
__ Set(target, Immediate(bits & 0x0000FFFF));
__ or_(target, bits & 0xFFFF0000);
__ Set(target, Immediate(bits ^ jit_cookie_));
__ xor_(target, jit_cookie_);
}

5
src/ia32/codegen-ia32.h
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@ -785,6 +785,11 @@ class CodeGenerator: public AstVisitor {
// in a spilled state.
bool in_spilled_code_;
// A cookie that is used for JIT IMM32 Encoding. Initialized to a
// random number when the command-line
// FLAG_mask_constants_with_cookie is true, zero otherwise.
int jit_cookie_;
friend class VirtualFrame;
friend class JumpTarget;
friend class Reference;