feat: revert changes to ValueMerger and Instruction::IfElse

compiler/noirc_evaluator/src/ssa/ir/instruction.rs

@@ -315,7 +315,12 @@ pub(crate) enum Instruction {
     ///     else_value
     /// }
     /// ```
-    IfElse { then_condition: ValueId, then_value: ValueId, else_value: ValueId },
+    IfElse {
+        then_condition: ValueId,
+        then_value: ValueId,
+        else_condition: ValueId,
+        else_value: ValueId,
+    },
 
     /// Creates a new array or slice.
     ///
@@ -632,11 +637,14 @@ impl Instruction {
                     assert_message: assert_message.clone(),
                 }
             }
-            Instruction::IfElse { then_condition, then_value, else_value } => Instruction::IfElse {
-                then_condition: f(*then_condition),
-                then_value: f(*then_value),
-                else_value: f(*else_value),
-            },
+            Instruction::IfElse { then_condition, then_value, else_condition, else_value } => {
+                Instruction::IfElse {
+                    then_condition: f(*then_condition),
+                    then_value: f(*then_value),
+                    else_condition: f(*else_condition),
+                    else_value: f(*else_value),
+                }
+            }
             Instruction::MakeArray { elements, typ } => Instruction::MakeArray {
                 elements: elements.iter().copied().map(f).collect(),
                 typ: typ.clone(),
@@ -695,9 +703,10 @@ impl Instruction {
             | Instruction::RangeCheck { value, .. } => {
                 f(*value);
             }
-            Instruction::IfElse { then_condition, then_value, else_value } => {
+            Instruction::IfElse { then_condition, then_value, else_condition, else_value } => {
                 f(*then_condition);
                 f(*then_value);
+                f(*else_condition);
                 f(*else_value);
             }
             Instruction::MakeArray { elements, typ: _ } => {
@@ -860,7 +869,7 @@ impl Instruction {
                     None
                 }
             }
-            Instruction::IfElse { then_condition, then_value, else_value } => {
+            Instruction::IfElse { then_condition, then_value, else_condition, else_value } => {
                 let typ = dfg.type_of_value(*then_value);
 
                 if let Some(constant) = dfg.get_numeric_constant(*then_condition) {
@@ -879,11 +888,13 @@ impl Instruction {
 
                 if matches!(&typ, Type::Numeric(_)) {
                     let then_condition = *then_condition;
+                    let else_condition = *else_condition;
 
                     let result = ValueMerger::merge_numeric_values(
                         dfg,
                         block,
                         then_condition,
+                        else_condition,
                         then_value,
                         else_value,
                     );

compiler/noirc_evaluator/src/ssa/ir/instruction/call.rs

@@ -465,8 +465,12 @@ fn simplify_slice_push_back(
     let mut value_merger =
         ValueMerger::new(dfg, block, &mut slice_sizes, unknown, None, call_stack);
 
-    let new_slice =
-        value_merger.merge_values(len_not_equals_capacity, set_last_slice_value, new_slice);
+    let new_slice = value_merger.merge_values(
+        len_not_equals_capacity,
+        len_equals_capacity,
+        set_last_slice_value,
+        new_slice,
+    );
 
     SimplifyResult::SimplifiedToMultiple(vec![new_slice_length, new_slice])
 }

compiler/noirc_evaluator/src/ssa/ir/printer.rs

@@ -209,11 +209,15 @@ fn display_instruction_inner(
         Instruction::RangeCheck { value, max_bit_size, .. } => {
             writeln!(f, "range_check {} to {} bits", show(*value), *max_bit_size,)
         }
-        Instruction::IfElse { then_condition, then_value, else_value } => {
+        Instruction::IfElse { then_condition, then_value, else_condition, else_value } => {
             let then_condition = show(*then_condition);
             let then_value = show(*then_value);
+            let else_condition = show(*else_condition);
             let else_value = show(*else_value);
-            writeln!(f, "if {then_condition} then {then_value} else {else_value}")
+            writeln!(
+                f,
+                "if {then_condition} then {then_value} else (if {else_condition}) {else_value}"
+            )
         }
         Instruction::MakeArray { elements, typ } => {
             write!(f, "make_array [")?;