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Unified Diff: src/code-stubs.cc

Issue 1753173003: [compiler] Introduce initial StrictEqualStub. (Closed) Base URL: https://chromium.googlesource.com/v8/v8.git@master
Patch Set: Add pseudo-code. Created 4 years, 10 months ago
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Index: src/code-stubs.cc
diff --git a/src/code-stubs.cc b/src/code-stubs.cc
index 2c4445f59ddf22316137d67c95693bdd3bb1e411..c5f7fb4fa1273f945115eae0e3bd9d48d60fb191 100644
--- a/src/code-stubs.cc
+++ b/src/code-stubs.cc
@@ -473,6 +473,290 @@ void StringLengthStub::GenerateAssembly(
assembler->Return(result);
}
+void StrictEqualStub::GenerateAssembly(
+ compiler::CodeStubAssembler* assembler) const {
+ // Here's pseudo-code for the algorithm below:
+ //
+ // if (lhs == rhs) {
+ // if (lhs->IsHeapNumber()) return HeapNumber::cast(lhs)->value() != NaN;
+ // return true;
+ // }
+ // if (!lhs->IsSmi()) {
+ // if (lhs->IsHeapNumber()) {
+ // if (rhs->IsSmi()) {
+ // return Smi::cast(rhs)->value() == HeapNumber::cast(lhs)->value();
+ // } else if (rhs->IsHeapNumber()) {
+ // return HeapNumber::cast(rhs)->value() ==
+ // HeapNumber::cast(lhs)->value();
+ // } else {
+ // return false;
+ // }
+ // } else {
+ // if (rhs->IsSmi()) {
+ // return false;
+ // } else {
+ // if (lhs->IsString()) {
+ // if (rhs->IsString()) {
+ // return %StringEqual(lhs, rhs);
+ // } else {
+ // return false;
+ // }
+ // } else if (lhs->IsSimd128()) {
+ // if (rhs->IsSimd128()) {
+ // return %StrictEqual(lhs, rhs);
+ // }
+ // } else {
+ // return false;
+ // }
+ // }
+ // }
+ // } else {
+ // if (rhs->IsSmi()) {
+ // return false;
+ // } else {
+ // if (rhs->IsHeapNumber()) {
+ // return Smi::cast(lhs)->value() == HeapNumber::cast(rhs)->value();
+ // } else {
+ // return false;
+ // }
+ // }
+ // }
+
+ typedef compiler::CodeStubAssembler::Label Label;
+ typedef compiler::Node Node;
+
+ Node* lhs = assembler->Parameter(0);
+ Node* rhs = assembler->Parameter(1);
+ Node* context = assembler->Parameter(2);
+
+ Label if_true(assembler), if_false(assembler);
+
+ // Check if {lhs} and {rhs} refer to the same object.
+ Label if_same(assembler), if_notsame(assembler);
+ assembler->Branch(assembler->WordEqual(lhs, rhs), &if_same, &if_notsame);
+
+ assembler->Bind(&if_same);
+ {
+ // The {lhs} and {rhs} reference the exact same value, yet we need special
+ // treatment for HeapNumber, as NaN is not equal to NaN.
+ // TODO(bmeurer): This seems to violate the SIMD.js specification, but it
+ // seems to be what is tested in the current SIMD.js testsuite.
+
+ // Check if {lhs} (and therefore {rhs}) is a Smi or a HeapObject.
+ Label if_lhsissmi(assembler), if_lhsisnotsmi(assembler);
+ assembler->Branch(assembler->WordIsSmi(lhs), &if_lhsissmi, &if_lhsisnotsmi);
+
+ assembler->Bind(&if_lhsisnotsmi);
+ {
+ // Load the map of {lhs}.
+ Node* lhs_map = assembler->LoadObjectField(lhs, HeapObject::kMapOffset);
+
+ // Check if {lhs} (and therefore {rhs}) is a HeapNumber.
+ Node* number_map = assembler->HeapNumberMapConstant();
+ Label if_lhsisnumber(assembler), if_lhsisnotnumber(assembler);
+ assembler->Branch(assembler->WordEqual(lhs_map, number_map),
+ &if_lhsisnumber, &if_lhsisnotnumber);
+
+ assembler->Bind(&if_lhsisnumber);
+ {
+ // Convert {lhs} (and therefore {rhs}) to floating point value.
+ Node* lhs_value = assembler->LoadHeapNumberValue(lhs);
+
+ // Check if the HeapNumber value is a NaN.
+ assembler->BranchIfFloat64IsNaN(lhs_value, &if_false, &if_true);
+ }
+
+ assembler->Bind(&if_lhsisnotnumber);
+ assembler->Goto(&if_true);
+ }
+
+ assembler->Bind(&if_lhsissmi);
+ assembler->Goto(&if_true);
+ }
+
+ assembler->Bind(&if_notsame);
+ {
+ // The {lhs} and {rhs} reference different objects, yet for Smi, HeapNumber,
+ // String and Simd128Value they can still be considered equal.
+ Node* number_map = assembler->HeapNumberMapConstant();
+
+ // Check if {lhs} is a Smi or a HeapObject.
+ Label if_lhsissmi(assembler), if_lhsisnotsmi(assembler);
+ assembler->Branch(assembler->WordIsSmi(lhs), &if_lhsissmi, &if_lhsisnotsmi);
+
+ assembler->Bind(&if_lhsisnotsmi);
+ {
+ // Load the map of {lhs}.
+ Node* lhs_map = assembler->LoadObjectField(lhs, HeapObject::kMapOffset);
+
+ // Check if {lhs} is a HeapNumber.
+ Label if_lhsisnumber(assembler), if_lhsisnotnumber(assembler);
+ assembler->Branch(assembler->WordEqual(lhs_map, number_map),
+ &if_lhsisnumber, &if_lhsisnotnumber);
+
+ assembler->Bind(&if_lhsisnumber);
+ {
+ // Check if {rhs} is a Smi or a HeapObject.
+ Label if_rhsissmi(assembler), if_rhsisnotsmi(assembler);
+ assembler->Branch(assembler->WordIsSmi(rhs), &if_rhsissmi,
+ &if_rhsisnotsmi);
+
+ assembler->Bind(&if_rhsissmi);
+ {
+ // Convert {lhs} and {rhs} to floating point values.
+ Node* lhs_value = assembler->LoadHeapNumberValue(lhs);
+ Node* rhs_value = assembler->SmiToFloat64(rhs);
+
+ // Perform a floating point comparison of {lhs} and {rhs}.
+ assembler->BranchIfFloat64Equal(lhs_value, rhs_value, &if_true,
+ &if_false);
+ }
+
+ assembler->Bind(&if_rhsisnotsmi);
+ {
+ // Load the map of {rhs}.
+ Node* rhs_map =
+ assembler->LoadObjectField(rhs, HeapObject::kMapOffset);
+
+ // Check if {rhs} is also a HeapNumber.
+ Label if_rhsisnumber(assembler), if_rhsisnotnumber(assembler);
+ assembler->Branch(assembler->WordEqual(rhs_map, number_map),
+ &if_rhsisnumber, &if_rhsisnotnumber);
+
+ assembler->Bind(&if_rhsisnumber);
+ {
+ // Convert {lhs} and {rhs} to floating point values.
+ Node* lhs_value = assembler->LoadHeapNumberValue(lhs);
+ Node* rhs_value = assembler->LoadHeapNumberValue(rhs);
+
+ // Perform a floating point comparison of {lhs} and {rhs}.
+ assembler->BranchIfFloat64Equal(lhs_value, rhs_value, &if_true,
+ &if_false);
+ }
+
+ assembler->Bind(&if_rhsisnotnumber);
+ assembler->Goto(&if_false);
+ }
+ }
+
+ assembler->Bind(&if_lhsisnotnumber);
+ {
+ // Check if {rhs} is a Smi or a HeapObject.
+ Label if_rhsissmi(assembler), if_rhsisnotsmi(assembler);
+ assembler->Branch(assembler->WordIsSmi(rhs), &if_rhsissmi,
+ &if_rhsisnotsmi);
+
+ assembler->Bind(&if_rhsissmi);
+ assembler->Goto(&if_false);
+
+ assembler->Bind(&if_rhsisnotsmi);
+ {
+ // Load the instance type of {lhs}.
+ Node* lhs_instance_type = assembler->LoadMapInstanceType(lhs_map);
+
+ // Check if {lhs} is a String.
+ Label if_lhsisstring(assembler), if_lhsisnotstring(assembler);
+ assembler->Branch(assembler->Int32LessThan(
+ lhs_instance_type,
+ assembler->Int32Constant(FIRST_NONSTRING_TYPE)),
+ &if_lhsisstring, &if_lhsisnotstring);
+
+ assembler->Bind(&if_lhsisstring);
+ {
+ // Load the instance type of {rhs}.
+ Node* rhs_instance_type = assembler->LoadInstanceType(rhs);
+
+ // Check if {rhs} is also a String.
+ Label if_rhsisstring(assembler), if_rhsisnotstring(assembler);
+ assembler->Branch(assembler->Int32LessThan(
+ rhs_instance_type, assembler->Int32Constant(
+ FIRST_NONSTRING_TYPE)),
+ &if_rhsisstring, &if_rhsisnotstring);
+
+ assembler->Bind(&if_rhsisstring);
+ {
+ // TODO(bmeurer): Optimize this further once the StringEqual
+ // functionality is available in TurboFan land.
+ assembler->TailCallRuntime(Runtime::kStringEqual, context, lhs,
+ rhs);
+ }
+
+ assembler->Bind(&if_rhsisnotstring);
+ assembler->Goto(&if_false);
+ }
+
+ assembler->Bind(&if_lhsisnotstring);
+ {
+ // Check if {lhs} is a Simd128Value.
+ Label if_lhsissimd128value(assembler),
+ if_lhsisnotsimd128value(assembler);
+ assembler->Branch(assembler->Word32Equal(
+ lhs_instance_type,
+ assembler->Int32Constant(SIMD128_VALUE_TYPE)),
+ &if_lhsissimd128value, &if_lhsisnotsimd128value);
+
+ assembler->Bind(&if_lhsissimd128value);
+ {
+ // TODO(bmeurer): Inline the Simd128Value equality check.
+ assembler->TailCallRuntime(Runtime::kStrictEqual, context, lhs,
+ rhs);
+ }
+
+ assembler->Bind(&if_lhsisnotsimd128value);
+ assembler->Goto(&if_false);
+ }
+ }
+ }
+ }
+
+ assembler->Bind(&if_lhsissmi);
+ {
+ // We already know that {lhs} and {rhs} are not reference equal, and {lhs}
+ // is a Smi; so {lhs} and {rhs} can only be strictly equal if {rhs} is a
+ // HeapNumber with an equal floating point value.
+
+ // Check if {rhs} is a Smi or a HeapObject.
+ Label if_rhsissmi(assembler), if_rhsisnotsmi(assembler);
+ assembler->Branch(assembler->WordIsSmi(rhs), &if_rhsissmi,
+ &if_rhsisnotsmi);
+
+ assembler->Bind(&if_rhsissmi);
+ assembler->Goto(&if_false);
+
+ assembler->Bind(&if_rhsisnotsmi);
+ {
+ // Load the map of the {rhs}.
+ Node* rhs_map = assembler->LoadObjectField(rhs, HeapObject::kMapOffset);
+
+ // The {rhs} could be a HeapNumber with the same value as {lhs}.
+ Label if_rhsisnumber(assembler), if_rhsisnotnumber(assembler);
+ assembler->Branch(assembler->WordEqual(rhs_map, number_map),
+ &if_rhsisnumber, &if_rhsisnotnumber);
+
+ assembler->Bind(&if_rhsisnumber);
+ {
+ // Convert {lhs} and {rhs} to floating point values.
+ Node* lhs_value = assembler->SmiToFloat64(lhs);
+ Node* rhs_value = assembler->LoadHeapNumberValue(rhs);
+
+ // Perform a floating point comparison of {lhs} and {rhs}.
+ assembler->BranchIfFloat64Equal(lhs_value, rhs_value, &if_true,
+ &if_false);
+ }
+
+ assembler->Bind(&if_rhsisnotnumber);
+ assembler->Goto(&if_false);
+ }
+ }
+ }
+
+ assembler->Bind(&if_true);
+ assembler->Return(assembler->BooleanConstant(true));
+
+ assembler->Bind(&if_false);
+ assembler->Return(assembler->BooleanConstant(false));
+}
+
void ToBooleanStub::GenerateAssembly(
compiler::CodeStubAssembler* assembler) const {
typedef compiler::Node Node;
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