Make fold_redundant_jumps() feature-gated on basic-blocks

cranelift/codegen/src/binemit/relaxation.rs

@@ -31,7 +31,7 @@ use crate::binemit::{CodeInfo, CodeOffset};
 use crate::cursor::{Cursor, FuncCursor};
 use crate::dominator_tree::DominatorTree;
 use crate::flowgraph::ControlFlowGraph;
-use crate::ir::{Ebb, Function, Inst, InstructionData, Opcode, Value, ValueList};
+use crate::ir::{Function, InstructionData, Opcode};
 use crate::isa::{EncInfo, TargetIsa};
 use crate::iterators::IteratorExtras;
 use crate::regalloc::RegDiversions;
@@ -39,13 +39,16 @@ use crate::timing;
 use crate::CodegenResult;
 use log::debug;
 
+#[cfg(feature = "basic-blocks")]
+use crate::ir::{Ebb, Inst, Value, ValueList};
+
 /// Relax branches and compute the final layout of EBB headers in `func`.
 ///
 /// Fill in the `func.offsets` table so the function is ready for binary emission.
 pub fn relax_branches(
     func: &mut Function,
-    cfg: &mut ControlFlowGraph,
-    domtree: &mut DominatorTree,
+    _cfg: &mut ControlFlowGraph,
+    _domtree: &mut DominatorTree,
     isa: &dyn TargetIsa,
 ) -> CodegenResult<CodeInfo> {
     let _tt = timing::relax_branches();
@@ -57,8 +60,8 @@ pub fn relax_branches(
     func.offsets.resize(func.dfg.num_ebbs());
 
     // Start by removing redundant jumps.
-    // FIXME: Temporarily disabled due to #916.
-    /* fold_redundant_jumps(func, cfg, domtree); */
+    #[cfg(feature = "basic-blocks")]
+    fold_redundant_jumps(func, _cfg, _domtree);
 
     // Convert jumps to fallthrough instructions where possible.
     fallthroughs(func);
@@ -146,6 +149,7 @@ pub fn relax_branches(
 
 /// Folds an instruction if it is a redundant jump.
 /// Returns whether folding was performed (which invalidates the CFG).
+#[cfg(feature = "basic-blocks")]
 fn try_fold_redundant_jump(
     func: &mut Function,
     cfg: &mut ControlFlowGraph,
@@ -243,6 +247,7 @@ fn try_fold_redundant_jump(
 
 /// Redirects `jump` instructions that point to other `jump` instructions to the final destination.
 /// This transformation may orphan some blocks.
+#[cfg(feature = "basic-blocks")]
 fn fold_redundant_jumps(
     func: &mut Function,
     cfg: &mut ControlFlowGraph,