Changeset 69743 in webkit for trunk/JavaScriptCore/assembler/MacroAssemblerARMv7.h

Timestamp:

Oct 13, 2010, 11:45:26 PM (15 years ago)

Author:

[email protected]

Message:

2010-10-13 David Goodwin <​[email protected]>

Reviewed by Oliver Hunt.

ARMv7 JIT should generated conditional branches when possible
​https://bugs.webkit.org/show_bug.cgi?id=47384

Use different jump padding sizes for conditional and unconditional
jumps (12 bytes and 10 bytes respectively). This allows the JIT to
include the IT instruction as part of the conditional jump sequence
which in turn allows it to optimize away the IT using an ARMv7
conditional branch instruction. Use 2-byte B(T1) and 4-byte B(T3) for
conditional branches when displacement is in range. Also use IT/B(T4)
for conditional branch when displacement does not fit in B(T3).

For unconditional jump, instruction selection options are:
B(T2), B(T4), MOVW/MOVT/BX. For conditional jump, instruction selection
options are: B(T1), B(T3), IT/B(T4), ITTT/MOVW/MOVT/BX.

• assembler/ARMv7Assembler.cpp:
• assembler/ARMv7Assembler.h: (JSC::ARMv7Assembler::JmpSrc::JmpSrc): (JSC::ARMv7Assembler::ifThenElse): (JSC::ARMv7Assembler::jumpSizeDelta): (JSC::ARMv7Assembler::canCompact): (JSC::ARMv7Assembler::computeJumpType): (JSC::ARMv7Assembler::link): (JSC::ARMv7Assembler::canBeJumpT1): (JSC::ARMv7Assembler::canBeJumpT3): (JSC::ARMv7Assembler::canBeJumpT4): (JSC::ARMv7Assembler::linkJumpT1): (JSC::ARMv7Assembler::linkJumpT3): (JSC::ARMv7Assembler::linkJumpT4): (JSC::ARMv7Assembler::linkConditionalJumpT4): (JSC::ARMv7Assembler::linkBX): (JSC::ARMv7Assembler::linkConditionalBX): (JSC::ARMv7Assembler::linkJumpAbsolute):
• assembler/LinkBuffer.h: (JSC::LinkBuffer::linkCode):
• assembler/MacroAssemblerARMv7.h: (JSC::MacroAssemblerARMv7::canCompact): (JSC::MacroAssemblerARMv7::computeJumpType): (JSC::MacroAssemblerARMv7::jumpSizeDelta): (JSC::MacroAssemblerARMv7::jump): (JSC::MacroAssemblerARMv7::nearCall): (JSC::MacroAssemblerARMv7::call): (JSC::MacroAssemblerARMv7::ret): (JSC::MacroAssemblerARMv7::tailRecursiveCall): (JSC::MacroAssemblerARMv7::makeJump): (JSC::MacroAssemblerARMv7::makeBranch):

File:

• trunk/JavaScriptCore/assembler/MacroAssemblerARMv7.h (modified) (11 diffs)

trunk/JavaScriptCore/assembler/MacroAssemblerARMv7.h

@@ -1 +1 @@
 /*
- * Copyright (C) 2009 Apple Inc. All rights reserved.
+ * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 University of Szeged
  *
@@ -47 +47 @@
 public:
     typedef ARMv7Assembler::LinkRecord LinkRecord;
+    typedef ARMv7Assembler::JumpType JumpType;
     typedef ARMv7Assembler::JumpLinkType JumpLinkType;
 
@@ -58 +59 @@
     Vector<LinkRecord>& jumpsToLink() { return m_assembler.jumpsToLink(); }
     void* unlinkedCode() { return m_assembler.unlinkedCode(); }
+    bool canCompact(JumpType jumpType) { return m_assembler.canCompact(jumpType); }
+    JumpLinkType computeJumpType(JumpType jumpType, const uint8_t* from, const uint8_t* to) { return m_assembler.computeJumpType(jumpType, from, to); }
     JumpLinkType computeJumpType(LinkRecord& record, const uint8_t* from, const uint8_t* to) { return m_assembler.computeJumpType(record, from, to); }
     void recordLinkOffsets(int32_t regionStart, int32_t regionEnd, int32_t offset) {return m_assembler.recordLinkOffsets(regionStart, regionEnd, offset); }
-    int jumpSizeDelta(JumpLinkType jumpLinkType) { return m_assembler.jumpSizeDelta(jumpLinkType); }
+    int jumpSizeDelta(JumpType jumpType, JumpLinkType jumpLinkType) { return m_assembler.jumpSizeDelta(jumpType, jumpLinkType); }
     void link(LinkRecord& record, uint8_t* from, uint8_t* to) { return m_assembler.link(record, from, to); }
 
@@ -987 +990 @@
     void jump(RegisterID target)
     {
-        m_assembler.bx(target, inUninterruptedSequence() ? ARMv7Assembler::JumpFullSize : ARMv7Assembler::JumpNoCondition);
+        m_assembler.bx(target, ARMv7Assembler::JumpFixed);
     }
 
@@ -994 +997 @@
     {
         load32(address, dataTempRegister);
-        m_assembler.bx(dataTempRegister, inUninterruptedSequence() ? ARMv7Assembler::JumpFullSize : ARMv7Assembler::JumpNoCondition);
+        m_assembler.bx(dataTempRegister, ARMv7Assembler::JumpFixed);
     }
 
@@ -1083 +1086 @@
     {
         moveFixedWidthEncoding(Imm32(0), dataTempRegister);
-        return Call(m_assembler.blx(dataTempRegister, ARMv7Assembler::JumpFullSize), Call::LinkableNear);
+        return Call(m_assembler.blx(dataTempRegister, ARMv7Assembler::JumpFixed), Call::LinkableNear);
     }
 
@@ -1089 +1092 @@
     {
         moveFixedWidthEncoding(Imm32(0), dataTempRegister);
-        return Call(m_assembler.blx(dataTempRegister, ARMv7Assembler::JumpFullSize), Call::Linkable);
+        return Call(m_assembler.blx(dataTempRegister, ARMv7Assembler::JumpFixed), Call::Linkable);
     }
 
     Call call(RegisterID target)
     {
-        return Call(m_assembler.blx(target, ARMv7Assembler::JumpFullSize), Call::None);
+        return Call(m_assembler.blx(target, ARMv7Assembler::JumpFixed), Call::None);
     }
 
@@ -1100 +1103 @@
     {
         load32(address, dataTempRegister);
-        return Call(m_assembler.blx(dataTempRegister, ARMv7Assembler::JumpFullSize), Call::None);
+        return Call(m_assembler.blx(dataTempRegister, ARMv7Assembler::JumpFixed), Call::None);
     }
 
     void ret()
     {
-        m_assembler.bx(linkRegister, ARMv7Assembler::JumpFullSize);
+        m_assembler.bx(linkRegister, ARMv7Assembler::JumpFixed);
     }
 
@@ -1205 +1208 @@
         // Like a normal call, but don't link.
         moveFixedWidthEncoding(Imm32(0), dataTempRegister);
-        return Call(m_assembler.bx(dataTempRegister, ARMv7Assembler::JumpFullSize), Call::Linkable);
+        return Call(m_assembler.bx(dataTempRegister, ARMv7Assembler::JumpFixed), Call::Linkable);
     }
 
@@ -1229 +1232 @@
     {
         moveFixedWidthEncoding(Imm32(0), dataTempRegister);
-        return m_assembler.bx(dataTempRegister, inUninterruptedSequence() ? ARMv7Assembler::JumpFullSize : ARMv7Assembler::JumpNoCondition);
+        return m_assembler.bx(dataTempRegister, inUninterruptedSequence() ? ARMv7Assembler::JumpNoConditionFixedSize : ARMv7Assembler::JumpNoCondition);
     }
 
@@ -1236 +1239 @@
         m_assembler.it(cond, true, true);
         moveFixedWidthEncoding(Imm32(0), dataTempRegister);
-        return m_assembler.bx(dataTempRegister, inUninterruptedSequence() ? ARMv7Assembler::JumpFullSize : ARMv7Assembler::JumpCondition, cond);
+        return m_assembler.bx(dataTempRegister, inUninterruptedSequence() ? ARMv7Assembler::JumpConditionFixedSize : ARMv7Assembler::JumpCondition, cond);
     }
     ARMv7Assembler::JmpSrc makeBranch(Condition cond) { return makeBranch(armV7Condition(cond)); }