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Unified Diff: src/ia32/builtins-ia32.cc

Issue 2031123003: Avoid creating weak cells for literal arrays that are empty of literals. (Closed) Base URL: https://chromium.googlesource.com/v8/v8.git@master
Patch Set: REBASE. Created 4 years, 6 months ago
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Index: src/ia32/builtins-ia32.cc
diff --git a/src/ia32/builtins-ia32.cc b/src/ia32/builtins-ia32.cc
index 41780679307e0424e7808fe491b77bb989b9d388..db558a7f5558c2160e2722e3f302b59e9a3f780f 100644
--- a/src/ia32/builtins-ia32.cc
+++ b/src/ia32/builtins-ia32.cc
@@ -896,13 +896,30 @@ void Builtins::Generate_CompileLazy(MacroAssembler* masm) {
const int bailout_id = BailoutId::None().ToInt();
__ cmp(temp, Immediate(Smi::FromInt(bailout_id)));
__ j(not_equal, &loop_bottom);
+
// Literals available?
+ Label got_literals, maybe_cleared_weakcell;
__ mov(temp, FieldOperand(map, index, times_half_pointer_size,
SharedFunctionInfo::kOffsetToPreviousLiterals));
+
+ // temp contains either a WeakCell pointing to the literals array or the
+ // literals array directly.
+ STATIC_ASSERT(WeakCell::kValueOffset == FixedArray::kLengthOffset);
+ __ JumpIfSmi(FieldOperand(temp, WeakCell::kValueOffset),
+ &maybe_cleared_weakcell);
+ // The WeakCell value is a pointer, therefore it's a valid literals array.
__ mov(temp, FieldOperand(temp, WeakCell::kValueOffset));
- __ JumpIfSmi(temp, &gotta_call_runtime);
+ __ jmp(&got_literals);
+
+ // We have a smi. If it's 0, then we are looking at a cleared WeakCell
+ // around the literals array, and we should visit the runtime. If it's > 0,
+ // then temp already contains the literals array.
+ __ bind(&maybe_cleared_weakcell);
+ __ cmp(FieldOperand(temp, WeakCell::kValueOffset), Immediate(0));
+ __ j(equal, &gotta_call_runtime);
// Save the literals in the closure.
+ __ bind(&got_literals);
__ mov(ecx, Operand(esp, 0));
__ mov(FieldOperand(ecx, JSFunction::kLiteralsOffset), temp);
__ push(index);
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