[baseline] Update EstimateInstructionSize

Adds a minimum estimated size.

Data suggests that estimated instruction size (+ relocation info size)
is linear to bytecode array length. This CL adds a constant for this
equation. The ratio remains the same.

This is important, because we want to increase success rate of
estimation when compiling on-heap.

When off-heap, we round up the assembler buffer to 4kB, so this CL
will only impact JS functions with more than 585 bytecodes, i.e, the
new added constant will be negligible.

Note: Relocation info (for Sparkplug) is usually so small that it is
not useful to have a separate zone for this.

Bug: v8:11872
Change-Id: I789e72f80b970d1f541965e7ae808b61c8174326
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3069155
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76144}

src/baseline/baseline-compiler.cc

@@ -241,8 +241,10 @@ namespace {
 // than pre-allocating a large enough buffer.
 #ifdef V8_TARGET_ARCH_IA32
 const int kAverageBytecodeToInstructionRatio = 5;
+const int kMinimumEstimatedInstructionSize = 200;
 #else
 const int kAverageBytecodeToInstructionRatio = 7;
+const int kMinimumEstimatedInstructionSize = 300;
 #endif
 std::unique_ptr<AssemblerBuffer> AllocateBuffer(
     Isolate* isolate, Handle<BytecodeArray> bytecodes,
@@ -258,9 +260,6 @@ std::unique_ptr<AssemblerBuffer> AllocateBuffer(
   if (code_location == BaselineCompiler::kOnHeap &&
       Code::SizeFor(estimated_size) <
           heap->MaxRegularHeapObjectSize(AllocationType::kCode)) {
-    // TODO(victorgomes): We're currently underestimating the size of the
-    // buffer, since we don't know how big the reloc info will be. We could
-    // use a separate zone vector for the RelocInfo.
     return NewOnHeapAssemblerBuffer(isolate, estimated_size);
   }
   return NewAssemblerBuffer(RoundUp(estimated_size, 4 * KB));
@@ -328,7 +327,8 @@ MaybeHandle<Code> BaselineCompiler::Build(Isolate* isolate) {
 }
 
 int BaselineCompiler::EstimateInstructionSize(BytecodeArray bytecode) {
-  return bytecode.length() * kAverageBytecodeToInstructionRatio;
+  return bytecode.length() * kAverageBytecodeToInstructionRatio +
+         kMinimumEstimatedInstructionSize;
 }
 
 interpreter::Register BaselineCompiler::RegisterOperand(int operand_index) {

test/inspector/cpu-profiler/coverage.js

@@ -5,6 +5,7 @@
 // Flags: --allow-natives-syntax --no-always-opt --opt
 // Flags: --no-stress-flush-code
 // Flags: --no-stress-incremental-marking
+// Flags: --no-baseline-batch-compilation
 
 var source =
 `

test/mjsunit/baseline/batch-compilation.js

@@ -4,8 +4,8 @@
 
 // Flags: --sparkplug --no-always-sparkplug --sparkplug-filter="test*"
 // Flags: --allow-natives-syntax --expose-gc --no-always-opt
-// Flags: --baseline-batch-compilation --baseline-batch-compilation-threshold=200
-// Flags: --scale-factor-for-feedback-allocation=4
+// Flags: --baseline-batch-compilation --baseline-batch-compilation-threshold=500
+// Flags: --scale-factor-for-feedback-allocation=2
 
 // Flags to drive Fuzzers into the right direction
 // TODO(v8:11853): Remove these flags once fuzzers handle flag implications