Remove inlined blocks from literals and reuse literal index

This is a simple approach that simply relies on the blocks being the last literals added, which works for the supported inlinings, and because the parser just added them, before getting to the corresponding message send, where inlining is triggered. So, we simply, from the back, remove the blocks just added. Signed-off-by: Stefan Marr <[email protected]>
smarr · Aug 12, 2024 · eb4d2ae · eb4d2ae
1 parent ca4a142
commit eb4d2ae
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Showing 3 changed files with 80 additions and 75 deletions.
diff --git a/src/trufflesom/src/trufflesom/compiler/bc/BytecodeMethodGenContext.java b/src/trufflesom/src/trufflesom/compiler/bc/BytecodeMethodGenContext.java
@@ -50,7 +50,6 @@
 import static trufflesom.interpreter.bc.Bytecodes.RETURN_SELF;
 import static trufflesom.interpreter.bc.Bytecodes.getBytecodeLength;
 import static trufflesom.vm.SymbolTable.strSelf;
-import static trufflesom.vm.SymbolTable.symSelf;
 
 import java.util.ArrayList;
 import java.util.Iterator;
@@ -300,7 +299,19 @@ public byte addLiteralIfAbsent(final Object lit, final ParserBc parser)
   }
 
   public byte addLiteral(final Object lit, final ParserBc parser) throws ParseError {
-    int i = literals.size();
+    int i = 0;
+
+    // first try to use an empty slot, which may have opend up from inlining
+    for (; i < literals.size(); i += 1) {
+      if (literals.get(i) == null) {
+        literals.set(i, lit);
+        return (byte) i;
+      }
+    }
+
+    // otherwise, just add it
+    // but make sure we don't exceed the maximum number of literals
+    i = literals.size();
     if (i > Byte.MAX_VALUE) {
       String methodSignature = holderGenc.getName().getString() + ">>" + signature;
       throw new ParseError(
@@ -309,6 +320,7 @@ public byte addLiteral(final Object lit, final ParserBc parser) throws ParseErro
               + " literal values. Please split the method. The literal to be added is: " + lit,
           Symbol.NONE, parser);
     }
+
     literals.add(lit);
     return (byte) i;
   }
@@ -801,6 +813,16 @@ public boolean optimizeReturnField() {
     return true;
   }
 
+  /**
+   * This works only, because we have a simple forward-pass parser,
+   * and inlining, where this is used, happens right after the block was added.
+   * This also means, we need to remove blocks in reverse order.
+   */
+  private SMethod getLastBlockMethodAndFreeLiteral(final byte blockLiteralIdx) {
+    assert blockLiteralIdx == literals.size() - 1;
+    return (SMethod) literals.removeLast();
+  }
+
   public boolean inlineIfTrueOrIfFalse(final ParserBc parser, final boolean ifTrue)
       throws ParseError {
     // HACK: we do assume that the receiver on the stack is a boolean
@@ -819,7 +841,7 @@ public boolean inlineIfTrueOrIfFalse(final ParserBc parser, final boolean ifTrue
     int jumpOffsetIdxToSkipTrueBranch = emitJumpOnBoolWithDummyOffset(this, ifTrue, false);
 
     // grab block's method, and inline it
-    SMethod toBeInlined = (SMethod) literals.get(blockLiteralIdx);
+    SMethod toBeInlined = getLastBlockMethodAndFreeLiteral(blockLiteralIdx);
 
     isCurrentlyInliningBlock = true;
     toBeInlined.getInvokable().inline(this, toBeInlined);
@@ -848,8 +870,8 @@ public boolean inlineIfTrueIfFalse(final ParserBc parser, final boolean isIfTrue
     byte block2LiteralIdx = bytecode.get(bytecode.size() - 1);
 
     // grab block's method, and inline it
-    SMethod toBeInlined1 = (SMethod) literals.get(block1LiteralIdx);
-    SMethod toBeInlined2 = (SMethod) literals.get(block2LiteralIdx);
+    SMethod toBeInlined2 = getLastBlockMethodAndFreeLiteral(block2LiteralIdx);
+    SMethod toBeInlined1 = getLastBlockMethodAndFreeLiteral(block1LiteralIdx);
 
     removeLastBytecodes(2); // remove the PUSH_BLOCK bytecodes
 
@@ -889,7 +911,7 @@ public boolean inlineAndOr(final ParserBc parser, final boolean isOr) throws Par
 
     int jumpOffsetIdxToSkipBranch = emitJumpOnBoolWithDummyOffset(this, !isOr, true);
 
-    SMethod toBeInlined = (SMethod) literals.get(blockLiteralIdx);
+    SMethod toBeInlined = getLastBlockMethodAndFreeLiteral(blockLiteralIdx);
 
     isCurrentlyInliningBlock = true;
     toBeInlined.getInvokable().inline(this, toBeInlined);
@@ -920,8 +942,8 @@ public boolean inlineWhileTrueOrFalse(final ParserBc parser, final boolean isWhi
     byte block2LiteralIdx = bytecode.get(bytecode.size() - 1);
 
     // grab block's method, and inline it
-    SMethod condMethod = (SMethod) literals.get(block1LiteralIdx);
-    SMethod bodyMethod = (SMethod) literals.get(block2LiteralIdx);
+    SMethod bodyMethod = getLastBlockMethodAndFreeLiteral(block2LiteralIdx);
+    SMethod condMethod = getLastBlockMethodAndFreeLiteral(block1LiteralIdx);
 
     removeLastBytecodes(2); // remove the PUSH_BLOCK bytecodes
 

diff --git a/tests/trufflesom/tests/BytecodeBlockTests.java b/tests/trufflesom/tests/BytecodeBlockTests.java
@@ -159,13 +159,12 @@ public void testBlockIfTrueArg() {
             + " #end\n"
             + "]");
 
-    assertEquals(15, bytecodes.length);
     check(bytecodes,
         t(5, Bytecodes.SEND),
         new BC(Bytecodes.JUMP_ON_FALSE_TOP_NIL, 4),
         Bytecodes.PUSH_ARG1,
         Bytecodes.POP,
-        Bytecodes.PUSH_CONSTANT);
+        Bytecodes.PUSH_CONSTANT_2);
   }
 
   @Test
@@ -177,12 +176,11 @@ public void testBlockIfTrueMethodArg() {
             + "]",
         "arg");
 
-    assertEquals(17, bytecodes.length);
     check(bytecodes,
         t(7, new BC(Bytecodes.JUMP_ON_FALSE_TOP_NIL, 6)),
         new BC(Bytecodes.PUSH_ARGUMENT, 1, 1),
         Bytecodes.POP,
-        Bytecodes.PUSH_CONSTANT);
+        Bytecodes.PUSH_CONSTANT_2);
   }
 
   private void blockIfReturnNonLocal(final String sel, final byte jumpBytecode) {
@@ -192,7 +190,6 @@ private void blockIfReturnNonLocal(final String sel, final byte jumpBytecode) {
         + " #end\n"
         + "]");
 
-    assertEquals(16, bytecodes.length);
     check(bytecodes,
         t(5, Bytecodes.SEND),
         new BC(jumpBytecode, 5),