Changeset 47802 in webkit for trunk/JavaScriptCore/assembler

Timestamp:

Aug 26, 2009, 6:16:53 PM (16 years ago)

Author:

[email protected]

Message:

x86-64 GTK broken due to code offsets changing, pointers sometimes packed into immediates.
​https://bugs.webkit.org/show_bug.cgi?id=28317

Reviewed by Olliejver Hunt.

We rely on a slightly OS X specific behaviour, that x86-64 applications have a 4Gb zero page,
so pointers are never representable as a 32-bit integer, and always have to be represented by
a separate immediate load instruction, rather than within the immediate field of an arithmetic
or memory operation.

We explicitly check for a couple of cases where a value might be representable in 32-bit, but
these probably never kick in on Mac OS, and only kick in to hose GTK. Deleting these does not
show a performance degradation on SunSpider. Remove.

• assembler/MacroAssemblerX86_64.h:

(JSC::MacroAssemblerX86_64::storePtr):
(JSC::MacroAssemblerX86_64::branchPtr):

File:

• trunk/JavaScriptCore/assembler/MacroAssemblerX86_64.h (modified) (2 diffs)

trunk/JavaScriptCore/assembler/MacroAssemblerX86_64.h

@@ -297 +297 @@
     void storePtr(ImmPtr imm, ImplicitAddress address)
     {
-        intptr_t ptr = imm.asIntptr();
-        if (CAN_SIGN_EXTEND_32_64(ptr))
-            m_assembler.movq_i32m(static_cast<int>(ptr), address.offset, address.base);
-        else {
-            move(imm, scratchRegister);
-            storePtr(scratchRegister, address);
-        }
+        move(imm, scratchRegister);
+        storePtr(scratchRegister, address);
     }
 
@@ -340 +335 @@
     Jump branchPtr(Condition cond, RegisterID left, ImmPtr right)
     {
-        intptr_t imm = right.asIntptr();
-        if (CAN_SIGN_EXTEND_32_64(imm)) {
-            if (!imm)
-                m_assembler.testq_rr(left, left);
-            else
-                m_assembler.cmpq_ir(imm, left);
-            return Jump(m_assembler.jCC(x86Condition(cond)));
-        } else {
-            move(right, scratchRegister);
-            return branchPtr(cond, left, scratchRegister);
-        }
+        move(right, scratchRegister);
+        return branchPtr(cond, left, scratchRegister);
     }