Do not create unassigned variables.

16 files changed, 50 insertions, 47 deletions

diff --git a/libyul/optimiser/FullInliner.cpp b/libyul/optimiser/FullInliner.cpp
index 04005847..95360dc3 100644
--- a/libyul/optimiser/FullInliner.cpp
+++ b/libyul/optimiser/FullInliner.cpp
@@ -168,6 +168,8 @@ vector<Statement> InlineModifier::performInline(Statement& _statement, FunctionC
 
 	m_driver.tentativelyUpdateCodeSize(function->name, m_currentFunction);
 
+	static Expression const zero{Literal{{}, LiteralKind::Number, YulString{"0"}, {}}};
+
 	// helper function to create a new variable that is supposed to model
 	// an existing variable.
 	auto newVariable = [&](TypedName const& _existingVariable, Expression* _value) {
@@ -176,6 +178,8 @@ vector<Statement> InlineModifier::performInline(Statement& _statement, FunctionC
 		VariableDeclaration varDecl{_funCall.location, {{_funCall.location, newName, _existingVariable.type}}, {}};
 		if (_value)
 			varDecl.value = make_shared<Expression>(std::move(*_value));
+		else
+			varDecl.value = make_shared<Expression>(zero);
 		newStatements.emplace_back(std::move(varDecl));
 	};
 
diff --git a/test/libyul/yulOptimizerTests/fullInliner/double_inline.yul b/test/libyul/yulOptimizerTests/fullInliner/double_inline.yul
index ee7f5bf5..b3f51593 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/double_inline.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/double_inline.yul
@@ -9,14 +9,14 @@
 // {
 //     {
 //         let f_a := calldataload(0)
-//         let f_b
-//         let f_c
+//         let f_b := 0
+//         let f_c := 0
 //         f_b := sload(mload(f_a))
 //         f_c := 3
 //         let b3 := f_b
 //         let f_a_2 := f_c
-//         let f_b_3
-//         let f_c_4
+//         let f_b_3 := 0
+//         let f_c_4 := 0
 //         f_b_3 := sload(mload(f_a_2))
 //         f_c_4 := 3
 //         let b4 := f_b_3
diff --git a/test/libyul/yulOptimizerTests/fullInliner/inside_condition.yul b/test/libyul/yulOptimizerTests/fullInliner/inside_condition.yul
index 00bb6577..9e6c4e76 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/inside_condition.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/inside_condition.yul
@@ -14,7 +14,7 @@
 //     {
 //         let _2 := mload(0)
 //         let f_a := mload(1)
-//         let f_r
+//         let f_r := 0
 //         f_a := mload(f_a)
 //         f_r := add(f_a, calldatasize())
 //         if gt(f_r, _2)
diff --git a/test/libyul/yulOptimizerTests/fullInliner/large_function_multi_use.yul b/test/libyul/yulOptimizerTests/fullInliner/large_function_multi_use.yul
index e0dad8b8..c00b1163 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/large_function_multi_use.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/large_function_multi_use.yul
@@ -23,7 +23,7 @@
 //         let a2 := 2
 //         let r := f(a_1)
 //         let f_a := a2
-//         let f_b
+//         let f_b := 0
 //         let f_x := mload(f_a)
 //         f_b := sload(f_x)
 //         let f_y := add(f_a, f_x)
@@ -31,7 +31,7 @@
 //         let t := f_b
 //         let a3
 //         let f_a_3 := a3
-//         let f_b_4
+//         let f_b_4 := 0
 //         let f_x_5 := mload(f_a_3)
 //         f_b_4 := sload(f_x_5)
 //         let f_y_6 := add(f_a_3, f_x_5)
diff --git a/test/libyul/yulOptimizerTests/fullInliner/large_function_single_use.yul b/test/libyul/yulOptimizerTests/fullInliner/large_function_single_use.yul
index 3302a35c..72beb8b1 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/large_function_single_use.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/large_function_single_use.yul
@@ -15,7 +15,7 @@
 // {
 //     {
 //         let f_a := mload(1)
-//         let f_b
+//         let f_b := 0
 //         let f_x := mload(f_a)
 //         f_b := sload(f_x)
 //         let f_c := 3
diff --git a/test/libyul/yulOptimizerTests/fullInliner/long_names.yul b/test/libyul/yulOptimizerTests/fullInliner/long_names.yul
index 644e9126..869abbc9 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/long_names.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/long_names.yul
@@ -13,7 +13,7 @@
 //     {
 //         let verylongvariablename2_1 := 3
 //         let verylongfu_verylongvariablename := verylongvariablename2_1
-//         let verylongfu_verylongvariablename2
+//         let verylongfu_verylongvariablename2 := 0
 //         verylongfu_verylongvariablename2 := add(verylongfu_verylongvariablename, verylongfu_verylongvariablename)
 //         mstore(0, verylongfu_verylongvariablename2)
 //         mstore(1, verylongvariablename2_1)
diff --git a/test/libyul/yulOptimizerTests/fullInliner/move_up_rightwards_argument.yul b/test/libyul/yulOptimizerTests/fullInliner/move_up_rightwards_argument.yul
index f3d0b286..0b46a3c6 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/move_up_rightwards_argument.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/move_up_rightwards_argument.yul
@@ -15,7 +15,7 @@
 //         let f_a := mload(2)
 //         let f_b := _6
 //         let f_c := _4
-//         let f_x
+//         let f_x := 0
 //         f_x := add(f_a, f_b)
 //         f_x := mul(f_x, f_c)
 //         let _10 := add(f_x, _2)
diff --git a/test/libyul/yulOptimizerTests/fullInliner/multi_fun.yul b/test/libyul/yulOptimizerTests/fullInliner/multi_fun.yul
index 8bc6ec58..5d658e96 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/multi_fun.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/multi_fun.yul
@@ -9,11 +9,11 @@
 //     {
 //         let _1 := 7
 //         let f_a := 3
-//         let f_x
+//         let f_x := 0
 //         f_x := add(f_a, f_a)
 //         let g_b := f_x
 //         let g_c := _1
-//         let g_y
+//         let g_y := 0
 //         g_y := mul(mload(g_c), f(g_b))
 //         let y_1 := g_y
 //     }
@@ -24,7 +24,7 @@
 //     function g(b, c) -> y
 //     {
 //         let f_a_6 := b
-//         let f_x_7
+//         let f_x_7 := 0
 //         f_x_7 := add(f_a_6, f_a_6)
 //         y := mul(mload(c), f_x_7)
 //     }
diff --git a/test/libyul/yulOptimizerTests/fullInliner/multi_fun_callback.yul b/test/libyul/yulOptimizerTests/fullInliner/multi_fun_callback.yul
index 19ac945e..6e4acb97 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/multi_fun_callback.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/multi_fun_callback.yul
@@ -37,7 +37,7 @@
 //     function f(x)
 //     {
 //         mstore(0, x)
-//         let h_t
+//         let h_t := 0
 //         h_t := 2
 //         mstore(7, h_t)
 //         let g_x_1 := 10
diff --git a/test/libyul/yulOptimizerTests/fullInliner/multi_return.yul b/test/libyul/yulOptimizerTests/fullInliner/multi_return.yul
index eebdec38..a4cbbef0 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/multi_return.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/multi_return.yul
@@ -11,8 +11,8 @@
 // {
 //     {
 //         let f_a := mload(0)
-//         let f_x
-//         let f_y
+//         let f_x := 0
+//         let f_y := 0
 //         f_x := mul(f_a, f_a)
 //         f_y := add(f_a, f_x)
 //         let r := f_x
diff --git a/test/libyul/yulOptimizerTests/fullInliner/no_inline_into_big_function.yul b/test/libyul/yulOptimizerTests/fullInliner/no_inline_into_big_function.yul
index 7b1558c0..f59e2c11 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/no_inline_into_big_function.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/no_inline_into_big_function.yul
@@ -19,25 +19,25 @@
 //     function g() -> x_1
 //     {
 //         let f_a := 2
-//         let f_b
+//         let f_b := 0
 //         f_b := sload(mload(f_a))
 //         let f_a_20 := f_b
-//         let f_b_21
+//         let f_b_21 := 0
 //         f_b_21 := sload(mload(f_a_20))
 //         let f_a_23 := f_b_21
-//         let f_b_24
+//         let f_b_24 := 0
 //         f_b_24 := sload(mload(f_a_23))
 //         let f_a_26 := f_b_24
-//         let f_b_27
+//         let f_b_27 := 0
 //         f_b_27 := sload(mload(f_a_26))
 //         let f_a_29 := f_b_27
-//         let f_b_30
+//         let f_b_30 := 0
 //         f_b_30 := sload(mload(f_a_29))
 //         let f_a_32 := f_b_30
-//         let f_b_33
+//         let f_b_33 := 0
 //         f_b_33 := sload(mload(f_a_32))
 //         let f_a_35 := f_b_33
-//         let f_b_36
+//         let f_b_36 := 0
 //         f_b_36 := sload(mload(f_a_35))
 //         x_1 := f(f(f(f(f(f(f(f(f(f(f(f(f_b_36))))))))))))
 //     }
diff --git a/test/libyul/yulOptimizerTests/fullInliner/no_inline_into_big_global_context.yul b/test/libyul/yulOptimizerTests/fullInliner/no_inline_into_big_global_context.yul
index c8c49d39..f20b7221 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/no_inline_into_big_global_context.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/no_inline_into_big_global_context.yul
@@ -12,25 +12,25 @@
 // {
 //     {
 //         let f_a := 2
-//         let f_b
+//         let f_b := 0
 //         f_b := sload(mload(f_a))
 //         let f_a_20 := f_b
-//         let f_b_21
+//         let f_b_21 := 0
 //         f_b_21 := sload(mload(f_a_20))
 //         let f_a_23 := f_b_21
-//         let f_b_24
+//         let f_b_24 := 0
 //         f_b_24 := sload(mload(f_a_23))
 //         let f_a_26 := f_b_24
-//         let f_b_27
+//         let f_b_27 := 0
 //         f_b_27 := sload(mload(f_a_26))
 //         let f_a_29 := f_b_27
-//         let f_b_30
+//         let f_b_30 := 0
 //         f_b_30 := sload(mload(f_a_29))
 //         let f_a_32 := f_b_30
-//         let f_b_33
+//         let f_b_33 := 0
 //         f_b_33 := sload(mload(f_a_32))
 //         let f_a_35 := f_b_33
-//         let f_b_36
+//         let f_b_36 := 0
 //         f_b_36 := sload(mload(f_a_35))
 //         let x_1 := f(f(f(f(f(f(f(f(f(f(f(f(f_b_36))))))))))))
 //     }
diff --git a/test/libyul/yulOptimizerTests/fullInliner/not_inside_for.yul b/test/libyul/yulOptimizerTests/fullInliner/not_inside_for.yul
index 9644e6c1..96d806bd 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/not_inside_for.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/not_inside_for.yul
@@ -14,7 +14,7 @@
 //     {
 //         for {
 //             let f_a := 0
-//             let f_r
+//             let f_r := 0
 //             sstore(f_a, 0)
 //             f_r := f_a
 //             let x := f_r
@@ -22,14 +22,14 @@
 //         f(x)
 //         {
 //             let f_a_3 := x
-//             let f_r_4
+//             let f_r_4 := 0
 //             sstore(f_a_3, 0)
 //             f_r_4 := f_a_3
 //             x := f_r_4
 //         }
 //         {
 //             let f_a_6 := x
-//             let f_r_7
+//             let f_r_7 := 0
 //             sstore(f_a_6, 0)
 //             f_r_7 := f_a_6
 //             let t := f_r_7
diff --git a/test/libyul/yulOptimizerTests/fullInliner/pop_result.yul b/test/libyul/yulOptimizerTests/fullInliner/pop_result.yul
index cd9e2746..c1bed208 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/pop_result.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/pop_result.yul
@@ -14,7 +14,7 @@
 //     {
 //         let _1 := 2
 //         let f_a := 7
-//         let f_x
+//         let f_x := 0
 //         let f_r := mul(f_a, f_a)
 //         f_x := add(f_r, f_r)
 //         pop(add(f_x, _1))
diff --git a/test/libyul/yulOptimizerTests/fullInliner/simple.yul b/test/libyul/yulOptimizerTests/fullInliner/simple.yul
index fcdf453b..1ada8f53 100644
--- a/test/libyul/yulOptimizerTests/fullInliner/simple.yul
+++ b/test/libyul/yulOptimizerTests/fullInliner/simple.yul
@@ -11,7 +11,7 @@
 //     {
 //         let _2 := mload(7)
 //         let f_a := sload(mload(2))
-//         let f_x
+//         let f_x := 0
 //         let f_r := mul(f_a, f_a)
 //         f_x := add(f_r, f_r)
 //         let y := add(f_x, _2)
diff --git a/test/libyul/yulOptimizerTests/fullSuite/abi_example1.yul b/test/libyul/yulOptimizerTests/fullSuite/abi_example1.yul
index a3d59ff4..efb846f2 100644
--- a/test/libyul/yulOptimizerTests/fullSuite/abi_example1.yul
+++ b/test/libyul/yulOptimizerTests/fullSuite/abi_example1.yul
@@ -463,12 +463,11 @@
 //         let _2 := 0
 //         let _485 := mload(_2)
 //         let abi_encode_pos := _1
-//         let abi_encode_end_67_610
 //         let abi_encode_length_68 := mload(_485)
 //         mstore(_1, abi_encode_length_68)
 //         abi_encode_pos := 64
 //         let abi_encode_srcPtr := add(_485, _1)
-//         let abi_encode_i_69 := abi_encode_end_67_610
+//         let abi_encode_i_69 := _2
 //         for {
 //         }
 //         lt(abi_encode_i_69, abi_encode_length_68)
@@ -476,21 +475,21 @@
 //             abi_encode_i_69 := add(abi_encode_i_69, 1)
 //         }
 //         {
-//             let _857 := mload(abi_encode_srcPtr)
-//             let abi_encode_pos_71_965 := abi_encode_pos
-//             let abi_encode_length_72_966 := 0x3
-//             let abi_encode_srcPtr_73_967 := _857
-//             let abi_encode_i_74_968 := _2
+//             let _863 := mload(abi_encode_srcPtr)
+//             let abi_encode_pos_71_971 := abi_encode_pos
+//             let abi_encode_length_72_972 := 0x3
+//             let abi_encode_srcPtr_73_973 := _863
+//             let abi_encode_i_74_974 := _2
 //             for {
 //             }
-//             lt(abi_encode_i_74_968, abi_encode_length_72_966)
+//             lt(abi_encode_i_74_974, abi_encode_length_72_972)
 //             {
-//                 abi_encode_i_74_968 := add(abi_encode_i_74_968, 1)
+//                 abi_encode_i_74_974 := add(abi_encode_i_74_974, 1)
 //             }
 //             {
-//                 mstore(abi_encode_pos_71_965, and(mload(abi_encode_srcPtr_73_967), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF))
-//                 abi_encode_srcPtr_73_967 := add(abi_encode_srcPtr_73_967, _1)
-//                 abi_encode_pos_71_965 := add(abi_encode_pos_71_965, _1)
+//                 mstore(abi_encode_pos_71_971, and(mload(abi_encode_srcPtr_73_973), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF))
+//                 abi_encode_srcPtr_73_973 := add(abi_encode_srcPtr_73_973, _1)
+//                 abi_encode_pos_71_971 := add(abi_encode_pos_71_971, _1)
 //             }
 //             abi_encode_srcPtr := add(abi_encode_srcPtr, _1)
 //             abi_encode_pos := add(abi_encode_pos, 0x60)