Reviewers: Vyacheslav Egorov,
Description:
MIPS: NaNs in the snapshot should be quiet according
to the MIPS FPU even when cross-building the snapshot.
This is based on code from Daniel Kalmar from
http://codereview.chromium.org/9910029/
Please review this at https://chromiumcodereview.appspot.com/10068006/
SVN Base: http://v8.googlecode.com/svn/branches/bleeding_edge/
Affected files:
M src/assembler.h
M src/mips/assembler-mips.h
M src/mips/assembler-mips.cc
M src/serialize.cc
Index: src/assembler.h
===================================================================
--- src/assembler.h (revision 11280)
+++ src/assembler.h (working copy)
@@ -62,6 +62,10 @@
Isolate* isolate() const { return isolate_; }
int jit_cookie() { return jit_cookie_; }
+ // Overwrite a host NaN with a quiet target NaN. Used by mksnapshot for
+ // cross-snapshotting.
+ static void QuietNaN(HeapObject* nan) { }
+
private:
Isolate* isolate_;
int jit_cookie_;
Index: src/mips/assembler-mips.cc
===================================================================
--- src/mips/assembler-mips.cc (revision 11280)
+++ src/mips/assembler-mips.cc (working copy)
@@ -2137,6 +2137,21 @@
}
+#define MIPS_QNAN_HI 0x7ff7ffff
+#define MIPS_QNAN_LO 0xffffffff
+
+
+void Assembler::QuietNaN(HeapObject* object) {
+ // Mips has a different encoding of qNaN than ia32, so any heap NaN built
+ // with simulator must be re-encoded for the snapshot. Performance hit
not
+ // critical at mksnapshot/build time.
+ uint64_t mips_qnan_bits =
+ (static_cast<uint64_t>(MIPS_QNAN_HI) << 32) | MIPS_QNAN_LO;
+ Address value_ptr = object->address() + HeapNumber::kValueOffset;
+ memcpy(value_ptr, &mips_qnan_bits, sizeof(mips_qnan_bits));
+}
+
+
// On Mips, a target address is stored in a lui/ori instruction pair, each
// of which load 16 bits of the 32-bit address to a register.
// Patching the address must replace both instr, and flush the i-cache.
Index: src/mips/assembler-mips.h
===================================================================
--- src/mips/assembler-mips.h (revision 11280)
+++ src/mips/assembler-mips.h (working copy)
@@ -570,6 +570,8 @@
static void JumpLabelToJumpRegister(Address pc);
+ static void QuietNaN(HeapObject* nan);
+
// This sets the branch destination (which gets loaded at the call
address).
// This is for calls and branches within generated code. The serializer
// has already deserialized the lui/ori instructions etc.
Index: src/serialize.cc
===================================================================
--- src/serialize.cc (revision 11280)
+++ src/serialize.cc (working copy)
@@ -1444,6 +1444,8 @@
sink_->PutSection(space, "NewPageSpace");
}
+ if (object_->IsNaN()) Assembler::QuietNaN(object_);
+
// Serialize the map (first word of the object).
serializer_->SerializeObject(object_->map(), kPlain, kStartOfObject);
--
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