Changeset 86999 in webkit

Timestamp:

May 20, 2011 4:20:48 PM (13 years ago)

Author:

oliver@apple.com

Message:

2011-05-20 Oliver Hunt <​oliver@apple.com>

Reviewed by Gavin Barraclough.

Reduce size of inline cache path of get_by_id on ARMv7
​https://bugs.webkit.org/show_bug.cgi?id=61221

This reduces the code size of get_by_id by 20 bytes

• assembler/ARMv7Assembler.h: (JSC::ARMv7Assembler::ldrCompact): (JSC::ARMv7Assembler::repatchCompact): (JSC::ARMv7Assembler::setUInt7ForLoad):
• assembler/MacroAssemblerARMv7.h: (JSC::MacroAssemblerARMv7::load32WithCompactAddressOffsetPatch):
• jit/JIT.h:

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• assembler/ARMv7Assembler.h (modified) (3 diffs)
• assembler/MacroAssemblerARMv7.h (modified) (2 diffs)
• jit/JIT.h (modified) (1 diff)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2011-05-20  Oliver Hunt  <oliver@apple.com>
+
+        Reviewed by Gavin Barraclough.
+
+        Reduce size of inline cache path of get_by_id on ARMv7
+        https://bugs.webkit.org/show_bug.cgi?id=61221
+
+        This reduces the code size of get_by_id by 20 bytes
+
+        * assembler/ARMv7Assembler.h:
+        (JSC::ARMv7Assembler::ldrCompact):
+        (JSC::ARMv7Assembler::repatchCompact):
+        (JSC::ARMv7Assembler::setUInt7ForLoad):
+        * assembler/MacroAssemblerARMv7.h:
+        (JSC::MacroAssemblerARMv7::load32WithCompactAddressOffsetPatch):
+        * jit/JIT.h:
+
 2011-05-20  Zoltan Herczeg  <zherczeg@inf.u-szeged.hu>
 

trunk/Source/JavaScriptCore/assembler/ARMv7Assembler.h

@@ -954 +954 @@
     }
 
+    void ldrCompact(RegisterID rt, RegisterID rn, ARMThumbImmediate imm)
+    {
+        ASSERT(rn != ARMRegisters::pc); // LDR (literal)
+        ASSERT(imm.isUInt7());
+        ASSERT(!((rt | rn) & 8));
+        m_formatter.oneWordOp5Imm5Reg3Reg3(OP_LDR_imm_T1, imm.getUInt7() >> 2, rn, rt);
+    }
+
     // If index is set, this is a regular offset or a pre-indexed load;
     // if index is not set then is is a post-index load.
@@ -1757 +1765 @@
     static void repatchCompact(void* where, int32_t value)
     {
-        repatchInt32(where, value);
+        ASSERT(value >= 0);
+        ASSERT(ARMThumbImmediate::makeUInt12(value).isUInt7());
+        setUInt7ForLoad(where, ARMThumbImmediate::makeUInt12(value));
     }
 
@@ -1846 +1856 @@
 
         ExecutableAllocator::cacheFlush(location - 4, 4 * sizeof(uint16_t));
+    }
+
+    static void setUInt7ForLoad(void* code, ARMThumbImmediate imm)
+    {
+        // Requires us to have planted a LDR_imm_T1
+        ASSERT(imm.isValid());
+        ASSERT(imm.isUInt7());
+        uint16_t* location = reinterpret_cast<uint16_t*>(code);
+        location[0] |= (imm.getUInt7() >> 2) << 6;
+        ExecutableAllocator::cacheFlush(location, sizeof(uint16_t));
     }
 

trunk/Source/JavaScriptCore/assembler/MacroAssemblerARMv7.h

@@ -49 +49 @@
     typedef ARMv7Assembler::JumpType JumpType;
     typedef ARMv7Assembler::JumpLinkType JumpLinkType;
-    static const int MaximumCompactPtrAlignedAddressOffset = 0x7FFFFFFF;
+    // Magic number is the biggest useful offset we can get on ARMv7 with
+    // a LDR_imm_T2 encoding
+    static const int MaximumCompactPtrAlignedAddressOffset = 124;
 
     MacroAssemblerARMv7()
@@ -486 +488 @@
     DataLabelCompact load32WithCompactAddressOffsetPatch(Address address, RegisterID dest)
     {
-        DataLabel32 label = load32WithAddressOffsetPatch(address, dest);
-        return DataLabelCompact(label.label());
+        DataLabelCompact label(this);
+        ASSERT(address.offset >= 0);
+        ASSERT(address.offset <= MaximumCompactPtrAlignedAddressOffset);
+        ASSERT(ARMThumbImmediate::makeUInt12(address.offset).isUInt7());
+        m_assembler.ldrCompact(dest, address.base, ARMThumbImmediate::makeUInt12(address.offset));
+        return label;
     }
 

trunk/Source/JavaScriptCore/jit/JIT.h

@@ -409 +409 @@
         static const int patchOffsetGetByIdStructure = 10;
         static const int patchOffsetGetByIdBranchToSlowCase = 26;
-        static const int patchOffsetGetByIdPropertyMapOffset1 = 36;
-        static const int patchOffsetGetByIdPropertyMapOffset2 = 48;
-        static const int patchOffsetGetByIdPutResult = 52;
+        static const int patchOffsetGetByIdPropertyMapOffset1 = 28;
+        static const int patchOffsetGetByIdPropertyMapOffset2 = 30;
+        static const int patchOffsetGetByIdPutResult = 32;
 #if ENABLE(OPCODE_SAMPLING)
         #error "OPCODE_SAMPLING is not yet supported"