perf: reduce repeated eval STRING overhead (#1911)

dev/bench/benchmark_eval_string_stats.pl

@@ -0,0 +1,78 @@
+use strict;
+use warnings;
+use Time::HiRes qw(time);
+
+my $trials  = 10;
+my $n       = 200_000;
+
+my $count = 0;
+my $k     = 0;
+
+sub run_uncached {
+    my @times;
+    for my $t (1 .. $trials) {
+        $k = 0;
+        $count = 0;
+        my $start = time();
+        for (1 .. $n) {
+            $k++;
+            my $str = '
+                while ( $k < 40 ) {
+                    $k = $k + 1;
+                    $count = $count + 1;
+                }
+            ' . "# " . $k;
+            eval $str;
+        }
+        push @times, time() - $start;
+    }
+    return @times;
+}
+
+sub run_cached {
+    my @times;
+    my $str = 'my $x = 1';
+    for my $t (1 .. $trials) {
+        my $start = time();
+        for (1 .. $n) {
+            eval $str;
+        }
+        push @times, time() - $start;
+    }
+    return @times;
+}
+
+sub stats {
+    my @vals = @_;
+    my $sum  = 0; $sum += $_ for @vals;
+    my $mean = $sum / @vals;
+    my $ss   = 0; $ss += ($_ - $mean)**2 for @vals;
+    my $sd   = sqrt($ss / (@vals - 1));
+    my $se   = $sd / sqrt(scalar @vals);
+    return ($mean, $sd, $se);
+}
+
+sub report {
+    my ($label, $n_iter, @times) = @_;
+    my ($mean, $sd, $se) = stats(@times);
+    my $us = $mean / $n_iter * 1e6;
+    my $us_se = $se / $n_iter * 1e6;
+    printf "  %-10s %d trials x %d iters: %.3f +/- %.3f s  (%.2f +/- %.2f us/eval)\n",
+        $label, scalar @times, $n_iter, $mean, $se, $us, $us_se;
+    return ($us, $us_se);
+}
+
+print "=== eval STRING benchmark ($trials trials x $n iterations) ===\n\n";
+
+print "Uncached (unique eval string each call):\n";
+my @t = run_uncached();
+my ($us, $us_se) = report("", $n, @t);
+
+print "\nCached (same eval string each call):\n";
+my @tc = run_cached();
+my ($us_c, $us_c_se) = report("", $n, @tc);
+
+my $engine = $ENV{JPERL_OPTS} ? "jperl" : ($^X =~ /jperl/ ? "jperl" : "perl");
+printf "\nEngine: %s  (%s)\n", $engine, $^X;
+printf "Uncached: %.2f +/- %.2f us/eval\n", $us, $us_se;
+printf "Cached:   %.2f +/- %.2f us/eval\n", $us_c, $us_c_se;

dev/bench/compare_eval_string.sh

@@ -0,0 +1,91 @@
+#!/bin/bash
+# Compare eval STRING performance: Perl vs PerlOnJava
+# Interleaves trials to account for CPU variability.
+# Usage: ./dev/bench/compare_eval_string.sh [trials] [iters]
+
+set -euo pipefail
+cd "$(dirname "$0")/../.."
+
+TRIALS=${1:-10}
+N=${2:-200000}
+
+cat > /tmp/bench_eval_trial.pl << 'PERL'
+use strict; use warnings; use Time::HiRes qw(time);
+my $n = $ARGV[0] || 200_000;
+my $mode = $ARGV[1] || 'uncached';
+my ($count, $k) = (0, 0);
+my $start = time();
+if ($mode eq 'cached') {
+    my $str = 'my $x = 1';
+    for (1 .. $n) { eval $str }
+} else {
+    for (1 .. $n) {
+        $k++;
+        my $str = 'while ($k < 40) { $k = $k + 1; $count = $count + 1; }' . "# $k";
+        eval $str;
+    }
+}
+printf "%.6f\n", time() - $start;
+PERL
+
+run_trial() {
+    local engine=$1 mode=$2
+    if [ "$engine" = "perl" ]; then
+        perl /tmp/bench_eval_trial.pl "$N" "$mode"
+    else
+        timeout 300 ./jperl /tmp/bench_eval_trial.pl "$N" "$mode"
+    fi
+}
+
+echo "=== eval STRING: Perl vs PerlOnJava ($TRIALS trials x $N iters) ==="
+echo ""
+
+for mode in uncached cached; do
+    perl_times=()
+    jperl_times=()
+
+    # Warmup
+    run_trial perl "$mode" > /dev/null
+    run_trial jperl "$mode" > /dev/null
+
+    # Interleaved trials
+    for i in $(seq 1 "$TRIALS"); do
+        p=$(run_trial perl "$mode")
+        j=$(run_trial jperl "$mode")
+        perl_times+=("$p")
+        jperl_times+=("$j")
+        # Compute per-trial ratio
+        ratio=$(echo "$j / $p" | bc -l)
+        printf "  trial %2d: perl=%.3fs  jperl=%.3fs  ratio=%.1fx\n" "$i" "$p" "$j" "$ratio"
+    done
+
+    # Compute stats with awk
+    echo ""
+    echo "${perl_times[@]}" | tr ' ' '\n' | awk -v n="$N" -v label="perl" '
+    { a[NR]=$1; s+=$1 }
+    END {
+        m=s/NR; ss=0; for(i=1;i<=NR;i++) ss+=(a[i]-m)^2
+        sd=sqrt(ss/(NR-1)); se=sd/sqrt(NR)
+        us=m/n*1e6; us_se=se/n*1e6
+        printf "  %-8s mean=%.3f +/- %.3f s  (%.2f +/- %.2f us/eval)\n", label, m, se, us, us_se
+    }'
+    echo "${jperl_times[@]}" | tr ' ' '\n' | awk -v n="$N" -v label="jperl" '
+    { a[NR]=$1; s+=$1 }
+    END {
+        m=s/NR; ss=0; for(i=1;i<=NR;i++) ss+=(a[i]-m)^2
+        sd=sqrt(ss/(NR-1)); se=sd/sqrt(NR)
+        us=m/n*1e6; us_se=se/n*1e6
+        printf "  %-8s mean=%.3f +/- %.3f s  (%.2f +/- %.2f us/eval)\n", label, m, se, us, us_se
+    }'
+
+    # Compute paired ratio with t-test
+    paste <(printf '%s\n' "${perl_times[@]}") <(printf '%s\n' "${jperl_times[@]}") | awk -v mode="$mode" '
+    { r[NR]=$2/$1; s+=r[NR] }
+    END {
+        m=s/NR; ss=0; for(i=1;i<=NR;i++) ss+=(r[i]-m)^2
+        sd=sqrt(ss/(NR-1)); se=sd/sqrt(NR)
+        t=(m-1)/se
+        printf "\n  %s ratio: %.2fx +/- %.2f  (paired t vs 1.0: t=%.1f, df=%d)\n", mode, m, se, t, NR-1
+    }'
+    echo ""
+done

src/main/java/org/perlonjava/backend/bytecode/BytecodeCompiler.java

@@ -1007,6 +1007,7 @@ private void enterScope() {
             st.warningFlagsStack.push((java.util.BitSet) st.warningFlagsStack.peek().clone());
             st.warningFatalStack.push((java.util.BitSet) st.warningFatalStack.peek().clone());
             st.warningDisabledStack.push((java.util.BitSet) st.warningDisabledStack.peek().clone());
+            st.invalidateWarningBitsCache();
         }
     }
 
@@ -1043,6 +1044,7 @@ private void exitScope(boolean flush) {
                 st.warningFlagsStack.pop();
                 st.warningFatalStack.pop();
                 st.warningDisabledStack.pop();
+                st.invalidateWarningBitsCache();
             }
         }
     }
@@ -1273,6 +1275,7 @@ private void inheritPragmaFlags(BytecodeCompiler subCompiler) {
         subCompiler.symbolTable.warningFatalStack.push((java.util.BitSet) parentST.warningFatalStack.peek().clone());
         subCompiler.symbolTable.warningDisabledStack.pop();
         subCompiler.symbolTable.warningDisabledStack.push((java.util.BitSet) parentST.warningDisabledStack.peek().clone());
+        subCompiler.symbolTable.invalidateWarningBitsCache();
     }
 
     /**
@@ -1533,6 +1536,7 @@ public InterpretedCode compile(Node node, EmitterContext ctx) {
                 symbolTable.strictOptionsStack.push(ctx.symbolTable.strictOptionsStack.peek());
                 symbolTable.featureFlagsStack.pop();
                 symbolTable.featureFlagsStack.push(ctx.symbolTable.featureFlagsStack.peek());
+                symbolTable.invalidateWarningBitsCache();
                 symbolTable.warningFlagsStack.pop();
                 symbolTable.warningFlagsStack.push((java.util.BitSet) ctx.symbolTable.warningFlagsStack.peek().clone());
                 symbolTable.warningFatalStack.pop();
@@ -9226,6 +9230,7 @@ public void visit(LabelNode node) {
     public void visit(CompilerFlagNode node) {
         if (emitterContext != null && emitterContext.symbolTable != null) {
             ScopedSymbolTable st = emitterContext.symbolTable;
+            st.invalidateWarningBitsCache();
             st.warningFlagsStack.pop();
             st.warningFlagsStack.push((java.util.BitSet) node.getWarningFlags().clone());
             st.warningFatalStack.pop();
@@ -9247,6 +9252,7 @@ public void visit(CompilerFlagNode node) {
         symbolTable.warningFatalStack.push((java.util.BitSet) node.getWarningFatalFlags().clone());
         symbolTable.warningDisabledStack.pop();
         symbolTable.warningDisabledStack.push((java.util.BitSet) node.getWarningDisabledFlags().clone());
+        symbolTable.invalidateWarningBitsCache();
 
         int warningBitsIdx = addToStringPool(symbolTable.getWarningBitsString());
         emit(Opcodes.APPLY_COMPILER_FLAGS);

src/main/java/org/perlonjava/backend/bytecode/EvalStringHandler.java

@@ -560,6 +560,7 @@ private static RuntimeList evalStringList(String perlCode,
                 symbolTable.strictOptionsStack.push(strictOpts);
                 symbolTable.featureFlagsStack.pop();
                 symbolTable.featureFlagsStack.push(featFlags);
+                symbolTable.invalidateWarningBitsCache();
                 symbolTable.warningFlagsStack.pop();
                 symbolTable.warningFlagsStack.push((java.util.BitSet) currentCode.warningFlags.clone());
                 WarningFlags.setWarningBitsFromString(symbolTable, siteWarningBits);

src/main/java/org/perlonjava/backend/jvm/EmitCompilerFlag.java

@@ -11,6 +11,7 @@ public static void emitCompilerFlag(EmitterContext ctx, CompilerFlagNode node) {
         ScopedSymbolTable currentScope = ctx.symbolTable;
 
         // Set the warning flags
+        currentScope.invalidateWarningBitsCache();
         currentScope.warningFlagsStack.pop();
         currentScope.warningFlagsStack.push((java.util.BitSet) node.getWarningFlags().clone());
 

src/main/java/org/perlonjava/backend/jvm/EmitSubroutine.java

@@ -236,6 +236,7 @@ && isDirectLeafIntegerAddition(node.block, directLeafCaptures,
                         ? value
                         : ctx.symbolTable.strictOptionsStack.peek();
 
+        newSymbolTable.invalidateWarningBitsCache();
         newSymbolTable.warningFlagsStack.pop();
         newSymbolTable.warningFlagsStack.push(definitionWarningFlags);
         newSymbolTable.warningFatalStack.pop();

src/main/java/org/perlonjava/backend/jvm/EmitterMethodCreator.java

@@ -2466,6 +2466,7 @@ private static void applyCompilerFlagNodes(EmitterContext ctx, Node ast) {
                     // Apply disabled warning flags
                     currentScope.warningDisabledStack.pop();
                     currentScope.warningDisabledStack.push((java.util.BitSet) node.getWarningDisabledFlags().clone());
+                    currentScope.invalidateWarningBitsCache();
                 }
             }
         }

src/main/java/org/perlonjava/frontend/parser/SpecialBlockParser.java

@@ -46,21 +46,21 @@ public class SpecialBlockParser {
     private static final ThreadLocal<Deque<ScopedSymbolTable>> compileTimePragmaMutationScopes =
             ThreadLocal.withInitial(ArrayDeque::new);
 
-    private static Stack<BitSet> cloneBitSetStack(Stack<BitSet> source) {
-        Stack<BitSet> copy = new Stack<>();
+    private static ScopedSymbolTable.FastStack<BitSet> cloneBitSetStack(ScopedSymbolTable.FastStack<BitSet> source) {
+        ScopedSymbolTable.FastStack<BitSet> copy = new ScopedSymbolTable.FastStack<>();
         for (BitSet flags : source) {
             copy.push((BitSet) flags.clone());
         }
         return copy;
     }
 
-    private static Stack<Integer> cloneIntegerStack(Stack<Integer> source) {
-        Stack<Integer> copy = new Stack<>();
+    private static ScopedSymbolTable.FastStack<Integer> cloneIntegerStack(ScopedSymbolTable.FastStack<Integer> source) {
+        ScopedSymbolTable.FastStack<Integer> copy = new ScopedSymbolTable.FastStack<>();
         copy.addAll(source);
         return copy;
     }
 
-    private static <T> void restoreStack(Stack<T> target, Stack<T> source) {
+    private static <T> void restoreStack(ScopedSymbolTable.FastStack<T> target, ScopedSymbolTable.FastStack<T> source) {
         target.clear();
         target.addAll(source);
     }
@@ -507,11 +507,11 @@ static RuntimeList runSpecialBlock(Parser parser, String blockPhase, Node block,
         if (CompilerOptions.DEBUG_ENABLED) parser.ctx.logDebug("Special block captures " + parser.ctx.symbolTable.getAllVisibleVariables());
         RuntimeList result;
         boolean preserveCallerPragmas = !blockPhase.equals("BEGIN");
-        Stack<BitSet> savedWarningFlagsStack = null;
-        Stack<BitSet> savedWarningFatalStack = null;
-        Stack<BitSet> savedWarningDisabledStack = null;
-        Stack<Integer> savedFeatureFlagsStack = null;
-        Stack<Integer> savedStrictOptionsStack = null;
+        ScopedSymbolTable.FastStack<BitSet> savedWarningFlagsStack = null;
+        ScopedSymbolTable.FastStack<BitSet> savedWarningFatalStack = null;
+        ScopedSymbolTable.FastStack<BitSet> savedWarningDisabledStack = null;
+        ScopedSymbolTable.FastStack<Integer> savedFeatureFlagsStack = null;
+        ScopedSymbolTable.FastStack<Integer> savedStrictOptionsStack = null;
         if (preserveCallerPragmas) {
             savedWarningFlagsStack = cloneBitSetStack(parser.ctx.symbolTable.warningFlagsStack);
             savedWarningFatalStack = cloneBitSetStack(parser.ctx.symbolTable.warningFatalStack);

src/main/java/org/perlonjava/frontend/parser/StatementParser.java

@@ -173,21 +173,21 @@ private static void markInsideGiven(Node node) {
         if (node instanceof IfNode conditional) { markInsideGiven(conditional.condition); markInsideGiven(conditional.thenBranch); markInsideGiven(conditional.elseBranch); return; }
         if (node instanceof TernaryOperatorNode ternary) { markInsideGiven(ternary.condition); markInsideGiven(ternary.trueExpr); markInsideGiven(ternary.falseExpr); }
     }
-    private static Stack<BitSet> cloneBitSetStack(Stack<BitSet> source) {
-        Stack<BitSet> copy = new Stack<>();
+    private static ScopedSymbolTable.FastStack<BitSet> cloneBitSetStack(ScopedSymbolTable.FastStack<BitSet> source) {
+        ScopedSymbolTable.FastStack<BitSet> copy = new ScopedSymbolTable.FastStack<>();
         for (BitSet flags : source) {
             copy.push((BitSet) flags.clone());
         }
         return copy;
     }
 
-    private static Stack<Integer> cloneIntegerStack(Stack<Integer> source) {
-        Stack<Integer> copy = new Stack<>();
+    private static ScopedSymbolTable.FastStack<Integer> cloneIntegerStack(ScopedSymbolTable.FastStack<Integer> source) {
+        ScopedSymbolTable.FastStack<Integer> copy = new ScopedSymbolTable.FastStack<>();
         copy.addAll(source);
         return copy;
     }
 
-    private static <T> void restoreStack(Stack<T> target, Stack<T> source) {
+    private static <T> void restoreStack(ScopedSymbolTable.FastStack<T> target, ScopedSymbolTable.FastStack<T> source) {
         target.clear();
         target.addAll(source);
     }
@@ -1383,6 +1383,7 @@ public static Node parseUseDeclaration(Parser parser, LexerToken token) {
                             for (int i = 0; i < parser.ctx.symbolTable.warningFlagsStack.size(); i++) {
                                 parser.ctx.symbolTable.warningFlagsStack.set(i, (java.util.BitSet) currentWarnings.clone());
                             }
+                            parser.ctx.symbolTable.invalidateWarningBitsCache();
                         }
                     }
                 }
@@ -1544,11 +1545,11 @@ public static Node parseUseDeclaration(Parser parser, LexerToken token) {
                 // context. Its final lexical pragma state must not be copied back over the
                 // surrounding file scope; the actual pragma effect of a `use` statement happens
                 // below when import()/unimport() is invoked against parser.ctx.symbolTable.
-                Stack<BitSet> savedWarningFlagsStack = cloneBitSetStack(ctx.symbolTable.warningFlagsStack);
-                Stack<BitSet> savedWarningFatalStack = cloneBitSetStack(ctx.symbolTable.warningFatalStack);
-                Stack<BitSet> savedWarningDisabledStack = cloneBitSetStack(ctx.symbolTable.warningDisabledStack);
-                Stack<Integer> savedFeatureFlagsStack = cloneIntegerStack(ctx.symbolTable.featureFlagsStack);
-                Stack<Integer> savedStrictOptionsStack = cloneIntegerStack(ctx.symbolTable.strictOptionsStack);
+                ScopedSymbolTable.FastStack<BitSet> savedWarningFlagsStack = cloneBitSetStack(ctx.symbolTable.warningFlagsStack);
+                ScopedSymbolTable.FastStack<BitSet> savedWarningFatalStack = cloneBitSetStack(ctx.symbolTable.warningFatalStack);
+                ScopedSymbolTable.FastStack<BitSet> savedWarningDisabledStack = cloneBitSetStack(ctx.symbolTable.warningDisabledStack);
+                ScopedSymbolTable.FastStack<Integer> savedFeatureFlagsStack = cloneIntegerStack(ctx.symbolTable.featureFlagsStack);
+                ScopedSymbolTable.FastStack<Integer> savedStrictOptionsStack = cloneIntegerStack(ctx.symbolTable.strictOptionsStack);
                 RuntimeList args;
                 try {
                     // The implicit BEGIN wrapper that evaluates a use/no

src/main/java/org/perlonjava/frontend/parser/SubroutineParser.java

@@ -2571,13 +2571,14 @@ && isLexicalSubStorageReferenced(explicitlyUsedVars, entry.name())
         compilationBlock.setAnnotation("compiledSubroutineName", fullName);
 
         // Clone warning flags (critical for 'no warnings' pragmas)
+        filteredSnapshot.invalidateWarningBitsCache();
         filteredSnapshot.warningFlagsStack.pop(); // Remove the initial value pushed by enterScope
         filteredSnapshot.warningFlagsStack.push(definitionWarningFlags);
-        
+
         // Clone fatal warning flags (critical for 'use warnings FATAL' pragmas)
         filteredSnapshot.warningFatalStack.pop();
         filteredSnapshot.warningFatalStack.push(definitionWarningFatalFlags);
-        
+
         // Clone disabled warning flags (critical for 'no warnings' pragmas)
         filteredSnapshot.warningDisabledStack.pop();
         filteredSnapshot.warningDisabledStack.push(definitionWarningDisabledFlags);