cranelift: Pass source location through directly (#8471)

Stashing the source location in a side location is unnecessary: we
already have it where we need it.

cranelift/codegen/src/machinst/lower.rs

@@ -917,12 +917,11 @@ impl<'func, I: VCodeInst> Lower<'func, I> {
     }
 
     fn finish_ir_inst(&mut self, loc: RelSourceLoc) {
-        self.vcode.set_srcloc(loc);
         // The VCodeBuilder builds in reverse order (and reverses at
         // the end), but `ir_insts` is in forward order, so reverse
         // it.
         for inst in self.ir_insts.drain(..).rev() {
-            self.vcode.push(inst);
+            self.vcode.push(inst, loc);
         }
     }
 

cranelift/codegen/src/machinst/vcode.rs

@@ -248,9 +248,6 @@ pub struct VCodeBuilder<I: VCodeInst> {
     /// the concatenated branch_block_arg_range list.
     branch_block_arg_succ_start: usize,
 
-    /// Current source location.
-    cur_srcloc: RelSourceLoc,
-
     /// Debug-value label in-progress map, keyed by label. For each
     /// label, we keep disjoint ranges mapping to vregs. We'll flatten
     /// this into (vreg, range, label) tuples when done.
@@ -285,7 +282,6 @@ impl<I: VCodeInst> VCodeBuilder<I> {
             succ_start: 0,
             block_params_start: 0,
             branch_block_arg_succ_start: 0,
-            cur_srcloc: Default::default(),
             debug_info: FxHashMap::default(),
         }
     }
@@ -370,9 +366,9 @@ impl<I: VCodeInst> VCodeBuilder<I> {
 
     /// Push an instruction for the current BB and current IR inst
     /// within the BB.
-    pub fn push(&mut self, insn: I) {
+    pub fn push(&mut self, insn: I, loc: RelSourceLoc) {
         self.vcode.insts.push(insn);
-        self.vcode.srclocs.push(self.cur_srcloc);
+        self.vcode.srclocs.push(loc);
     }
 
     /// Add a successor block with branch args.
@@ -381,11 +377,6 @@ impl<I: VCodeInst> VCodeBuilder<I> {
         self.add_branch_args_for_succ(args);
     }
 
-    /// Set the current source location.
-    pub fn set_srcloc(&mut self, srcloc: RelSourceLoc) {
-        self.cur_srcloc = srcloc;
-    }
-
     /// Add a debug value label to a register.
     pub fn add_value_label(&mut self, reg: Reg, label: ValueLabel) {
         // We'll fix up labels in reverse(). Because we're generating