Changeset 252231 in webkit

Timestamp:

Nov 7, 2019 7:55:47 PM (4 years ago)

Author:

Tadeu Zagallo

Message:

Use fewer virtual registers in Wasm LLInt
​https://bugs.webkit.org/show_bug.cgi?id=203861

Reviewed by Saam Barati.

Reduce the number of virtual registers in two ways:

• Re-use arguments for result values (e.g. the result of add lhs, rhs should go in lhs, not a new virtual register)
• Re-use the argument register space for return values that should be placed in registers

• bytecode/BytecodeList.rb:
• generator/Wasm.rb:
• llint/WebAssembly.asm:
• wasm/WasmLLIntGenerator.cpp:

(JSC::Wasm::LLIntGenerator::callInformationFor):
(JSC::Wasm::LLIntGenerator::addReturn):
(JSC::Wasm::LLIntGenerator::addRefIsNull):
(JSC::Wasm::LLIntGenerator::addTableGet):
(JSC::Wasm::LLIntGenerator::addTableGrow):
(JSC::Wasm::LLIntGenerator::addGrowMemory):
(JSC::Wasm::LLIntGenerator::addSelect):
(JSC::Wasm::LLIntGenerator::load):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• bytecode/BytecodeList.rb (modified) (1 diff)
• generator/Wasm.rb (modified) (2 diffs)
• llint/WebAssembly.asm (modified) (1 diff)
• wasm/WasmLLIntGenerator.cpp (modified) (8 diffs)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2019-11-07  Tadeu Zagallo  <tzagallo@apple.com>
+
+        Use fewer virtual registers in Wasm LLInt
+        https://bugs.webkit.org/show_bug.cgi?id=203861
+
+        Reviewed by Saam Barati.
+
+        Reduce the number of virtual registers in two ways:
+        - Re-use arguments for result values (e.g. the result of add lhs, rhs should go in lhs, not a new virtual register)
+        - Re-use the argument register space for return values that should be placed in registers
+
+        * bytecode/BytecodeList.rb:
+        * generator/Wasm.rb:
+        * llint/WebAssembly.asm:
+        * wasm/WasmLLIntGenerator.cpp:
+        (JSC::Wasm::LLIntGenerator::callInformationFor):
+        (JSC::Wasm::LLIntGenerator::addReturn):
+        (JSC::Wasm::LLIntGenerator::addRefIsNull):
+        (JSC::Wasm::LLIntGenerator::addTableGet):
+        (JSC::Wasm::LLIntGenerator::addTableGrow):
+        (JSC::Wasm::LLIntGenerator::addGrowMemory):
+        (JSC::Wasm::LLIntGenerator::addSelect):
+        (JSC::Wasm::LLIntGenerator::load):
+
 2019-11-07  Robin Morisset  <rmorisset@apple.com>
 

trunk/Source/JavaScriptCore/bytecode/BytecodeList.rb

@@ -1288 +1288 @@
     }
 
-op :ret,
-    args: {
-        stackOffset: unsigned,
-    }
+op :ret
 
 op :switch,

trunk/Source/JavaScriptCore/generator/Wasm.rb

@@ -59 +59 @@
 auto LLIntGenerator::addOp<#{op_type(op)}>(ExpressionType lhs, ExpressionType rhs, ExpressionType& result) -> PartialResult
 {
-    result = newTemporary();
+    result = lhs;
     #{op.capitalized_name}::emit(this, result, lhs, rhs);
     return { };
@@ -71 +71 @@
 auto LLIntGenerator::addOp<#{op_type(op)}>(ExpressionType operand, ExpressionType& result) -> PartialResult
 {
-    result = newTemporary();
+    result = operand;
     #{op.capitalized_name}::emit(this, result, operand);
     return { };

trunk/Source/JavaScriptCore/llint/WebAssembly.asm

@@ -605 +605 @@
 unprefixedWasmOp(wasm_ret, WasmRet, macro(ctx)
     checkSwitchToJITForEpilogue()
-    wgetu(ctx, m_stackOffset, ws1)
-    lshifti 3, ws1
-    negi ws1
-    sxi2q ws1, ws1
-    addp cfr, ws1
     forEachArgumentGPR(macro (offset, gpr)
-        loadq offset[ws1], gpr
+        loadq -offset - 8 - CalleeSaveSpaceAsVirtualRegisters * 8[cfr], gpr
     end)
     forEachArgumentFPR(macro (offset, fpr)
-        loadd offset[ws1], fpr
+        loadd -offset - 8 - CalleeSaveSpaceAsVirtualRegisters * 8[cfr], fpr
     end)
     doReturn()

trunk/Source/JavaScriptCore/wasm/WasmLLIntGenerator.cpp

@@ -353 +353 @@
 
 
-    for (uint32_t i = 0; i < gprCount; i++)
-        registers.append(newTemporary());
-    for (uint32_t i = 0; i < fprCount; i++)
-        registers.append(newTemporary());
-
-    if (role == CallRole::Caller) {
+    if (role == CallRole::Callee) {
+        // Reuse the slots we allocated to spill the registers in addArguments
+        for (uint32_t i = gprCount + fprCount; i--;)
+            registers.append(new RegisterID(::JSC::virtualRegisterForLocal(numberOfLLIntCalleeSaveRegisters + i)));
+    } else {
+        for (uint32_t i = 0; i < gprCount; i++)
+            registers.append(newTemporary());
+        for (uint32_t i = 0; i < fprCount; i++)
+            registers.append(newTemporary());
+
         for (uint32_t i = 0; i < signature.argumentCount(); i++)
             allocateStackRegister(signature.argument(i));
@@ -630 +634 @@
     LLIntCallInformation info = callInformationFor(*data.m_signature, CallRole::Callee);
     unifyValuesWithBlock(info.results, returnValues);
-    WasmRet::emit(this, info.stackOffset);
+    WasmRet::emit(this);
 
     return { };
@@ -748 +752 @@
 auto LLIntGenerator::addRefIsNull(ExpressionType value, ExpressionType& result) -> PartialResult
 {
-    result = newTemporary();
+    result = value;
     WasmRefIsNull::emit(this, result, value);
 
@@ -764 +768 @@
 auto LLIntGenerator::addTableGet(unsigned tableIndex, ExpressionType index, ExpressionType& result) -> PartialResult
 {
-    result = newTemporary();
+    result = index;
     WasmTableGet::emit(this, result, index, tableIndex);
 
@@ -787 +791 @@
 auto LLIntGenerator::addTableGrow(unsigned tableIndex, ExpressionType fill, ExpressionType delta, ExpressionType& result) -> PartialResult
 {
-    result = newTemporary();
+    result = fill;
     WasmTableGrow::emit(this, result, fill, delta, tableIndex);
 
@@ -817 +821 @@
 auto LLIntGenerator::addGrowMemory(ExpressionType delta, ExpressionType& result) -> PartialResult
 {
-    result = newTemporary();
+    result = delta;
     WasmGrowMemory::emit(this, result, delta);
 
@@ -825 +829 @@
 auto LLIntGenerator::addSelect(ExpressionType condition, ExpressionType nonZero, ExpressionType zero, ExpressionType& result) -> PartialResult
 {
-    result = newTemporary();
+    result = condition;
     WasmSelect::emit(this, result, condition, nonZero, zero);
 
@@ -833 +837 @@
 auto LLIntGenerator::load(LoadOpType op, ExpressionType pointer, ExpressionType& result, uint32_t offset) -> PartialResult
 {
-    result = newTemporary();
+    result = pointer;
     switch (op) {
     case LoadOpType::I32Load8S: