Merge pull request #5355 from ethereum/yul-forloop-pre-rewrite

[Yul] Implements a pass to rewrite for-loop's pre block into the parent's Block

test/libyul/YulOptimizerTest.cpp

@@ -31,6 +31,7 @@
 #include <libyul/optimiser/FunctionHoister.h>
 #include <libyul/optimiser/ExpressionInliner.h>
 #include <libyul/optimiser/FullInliner.h>
+#include <libyul/optimiser/ForLoopInitRewriter.h>
 #include <libyul/optimiser/MainFunction.h>
 #include <libyul/optimiser/Rematerialiser.h>
 #include <libyul/optimiser/ExpressionSimplifier.h>
@@ -108,6 +109,11 @@ bool YulOptimizerTest::run(ostream& _stream, string const& _linePrefix, bool con
 		disambiguate();
 		VarDeclPropagator{}(*m_ast);
 	}
+	else if (m_optimizerStep == "forLoopInitRewriter")
+	{
+		disambiguate();
+		ForLoopInitRewriter{}(*m_ast);
+	}
 	else if (m_optimizerStep == "commonSubexpressionEliminator")
 	{
 		disambiguate();

test/libyul/yulOptimizerTests/forLoopInitRewriter/complex_pre.yul

@@ -0,0 +1,23 @@
+{
+  let random := 42
+  for { let a := 1
+	    let b := 1 } iszero(eq(a, 10)) { a := add(a, b) } {
+    a := add(a, 1)
+  }
+}
+// ----
+// forLoopInitRewriter
+// {
+//     let random := 42
+//     let a := 1
+//     let b := 1
+//     for {
+//     }
+//     iszero(eq(a, 10))
+//     {
+//         a := add(a, b)
+//     }
+//     {
+//         a := add(a, 1)
+//     }
+// }

test/libyul/yulOptimizerTests/forLoopInitRewriter/empty_pre.yul

@@ -0,0 +1,20 @@
+{
+  let a := 1
+  for {} iszero(eq(a, 10)) { a := add(a, 1) } {
+    a := add(a, 1)
+  }
+}
+// ----
+// forLoopInitRewriter
+// {
+//     let a := 1
+//     for {
+//     }
+//     iszero(eq(a, 10))
+//     {
+//         a := add(a, 1)
+//     }
+//     {
+//         a := add(a, 1)
+//     }
+// }

test/libyul/yulOptimizerTests/forLoopInitRewriter/simple.yul

@@ -0,0 +1,21 @@
+{
+  let random := 42
+  for { let a := 1 } iszero(eq(a, 10)) { a := add(a, 1) } {
+    a := add(a, 1)
+  }
+}
+// ----
+// forLoopInitRewriter
+// {
+//     let random := 42
+//     let a := 1
+//     for {
+//     }
+//     iszero(eq(a, 10))
+//     {
+//         a := add(a, 1)
+//     }
+//     {
+//         a := add(a, 1)
+//     }
+// }

test/tools/yulopti.cpp

@@ -38,6 +38,7 @@
 #include <libyul/optimiser/FunctionHoister.h>
 #include <libyul/optimiser/ExpressionInliner.h>
 #include <libyul/optimiser/FullInliner.h>
+#include <libyul/optimiser/ForLoopInitRewriter.h>
 #include <libyul/optimiser/MainFunction.h>
 #include <libyul/optimiser/Rematerialiser.h>
 #include <libyul/optimiser/ExpressionSimplifier.h>
@@ -123,7 +124,7 @@ public:
 			}
 			cout << "(q)quit/(f)flatten/(c)se/propagate var(d)ecls/(x)plit/(j)oin/(g)rouper/(h)oister/" << endl;
 			cout << "  (e)xpr inline/(i)nline/(s)implify/(u)nusedprune/ss(a) transform/" << endl;
-			cout << "  (r)edundant assign elim./re(m)aterializer? ";
+			cout << "  (r)edundant assign elim./re(m)aterializer/f(o)r-loop-pre-rewriter? ";
 			cout.flush();
 			int option = readStandardInputChar();
 			cout << ' ' << char(option) << endl;
@@ -134,6 +135,9 @@ public:
 			case 'f':
 				BlockFlattener{}(*m_ast);
 				break;
+			case 'o':
+				ForLoopInitRewriter{}(*m_ast);
+				break;
 			case 'c':
 				(CommonSubexpressionEliminator{})(*m_ast);
 				break;