Commit ed7e2938ff2385d658f04248f1c757b324009be4 | zig

author	Joachim Schmidt <joachim.schmidt557@outlook.com> 2022-03-05 08:54:15+01:00
committer	Joachim Schmidt <joachim.schmidt557@outlook.com> 2022-03-05 08:56:01+01:00
log	ed7e2938ff2385d658f04248f1c757b324009be4
tree	ca45462b46d9babe9812e342ed941f16e9944e56
parent	691ec964efd50307a498fa35b715b52da144b857
signature	Commit is signed but in an unrecognized format.

stage2 AArch64: generate less no-op branches

mirroring d486a7b81188ea1e027334c81589157efde2ad23 for aarch64

1 files changed, 22 insertions(+), 9 deletions(-)

src
- arch
  - aarch64
    CodeGen.zig

src/arch/aarch64/CodeGen.zig+22-9

 @@ -443,14 +443,17 @@ fn gen(self: *Self) !void {
         });
         // exitlude jumps
-        if (self.exitlude_jump_relocs.items.len == 1) {
+        if (self.exitlude_jump_relocs.items.len > 0 and
-            // There is only one relocation. Hence,
+            self.exitlude_jump_relocs.items[self.exitlude_jump_relocs.items.len - 1] == self.mir_instructions.len - 2)
-            // this relocation must be at the end of
+        {
-            // the code. Therefore, we can just delete
+            // If the last Mir instruction (apart from the
-            // the space initially reserved for the
+            // dbg_epilogue_begin) is the last exitlude jump
-            // jump
+            // relocation (which would just jump one instruction
-            self.mir_instructions.orderedRemove(self.exitlude_jump_relocs.items[0]);
+            // further), it can be safely removed
-        } else for (self.exitlude_jump_relocs.items) |jmp_reloc| {
+            self.mir_instructions.orderedRemove(self.exitlude_jump_relocs.pop());
+        }
+        for (self.exitlude_jump_relocs.items) |jmp_reloc| {
             self.mir_instructions.set(jmp_reloc, .{
                 .tag = .b,
                 .data = .{ .inst = @intCast(u32, self.mir_instructions.len) },
 @@ -2958,7 +2961,17 @@ fn airBlock(self: *Self, inst: Air.Inst.Index) !void {
     const body = self.air.extra[extra.end..][0..extra.data.body_len];
     try self.genBody(body);
-    for (self.blocks.getPtr(inst).?.relocs.items) |reloc| try self.performReloc(reloc);
+    // relocations for `br` instructions
+    const relocs = &self.blocks.getPtr(inst).?.relocs;
+    if (relocs.items.len > 0 and relocs.items[relocs.items.len - 1] == self.mir_instructions.len - 1) {
+        // If the last Mir instruction is the last relocation (which
+        // would just jump one instruction further), it can be safely
+        // removed
+        self.mir_instructions.orderedRemove(relocs.pop());
+    }
+    for (relocs.items) |reloc| {
+        try self.performReloc(reloc);
+    }
     const result = self.blocks.getPtr(inst).?.mcv;
     return self.finishAir(inst, result, .{ .none, .none, .none });