Optimize function return

Author: Michael Skvortsov

llvm/lib/Target/TVM/TVMAsmPrinter.cpp

@@ -117,9 +117,9 @@ void TVMAsmPrinter::EmitInstruction(const MachineInstr *MI) {
   case TVM::FROM_BUILDER_COPY_S:
   case TVM::FROM_CELL_COPY_S:
     break;
-  case TVM::FALLTHROUGH_RETURN:
+  case TVM::RETURN_N_S:
     if (isVerbose()) {
-      OutStreamer->AddComment("fallthrough return");
+      OutStreamer->AddComment("implicit return");
       OutStreamer->AddBlankLine();
     }
     break;

llvm/lib/Target/TVM/TVMControlFlowInstrInfo.td

@@ -19,12 +19,8 @@
 //===----------------------------------------------------------------------===//
 
 let isTerminator = 1, hasCtrlDep = 1 in {
-  let isReturn = 1, isBarrier = 1 in {
-    defm RETURN_N : NRI<(outs), (ins variable_ops), [(TVMreturn)],
-                        "RET", 0xdb30>;
-    let isCodeGenOnly = 1 in
-    defm FALLTHROUGH_RETURN : SI<(ins)>;
-  } // isReturn = 1, isBarrier = 1
+  let isReturn = 1, isBarrier = 1 in
+    defm RETURN_N : NRI<(outs), (ins variable_ops), [(TVMreturn)]>;
 
   let isBranch = 1 in {
     // The condition operand is a boolean value which TVM represents as i257.

llvm/test/CodeGen/TVM/cfg.ll

@@ -11,11 +11,9 @@ entry:
 ; CHECK-NEXT: }
 ; CHECK-NEXT: PUSHCONT {
 ; CHECK-NEXT:   PUSHINT 42
-; CHECK-NEXT:   RET
 ; CHECK-NEXT: }
 ; CHECK-NEXT: PUSHCONT {
 ; CHECK-NEXT:   PUSHINT 77
-; CHECK-NEXT:   RET
 ; CHECK-NEXT: }
 ; CHECK-NEXT: BLKSWAP 1, 3
 ; CHECK-NEXT: PUSH s3
@@ -51,7 +49,6 @@ entry:
 ; CHECK-NEXT:   JMPX
 ; CHECK-NEXT: }
 ; CHECK-NEXT: PUSHCONT {
-; CHECK-NEXT:   RET
 ; CHECK-NEXT: }
 ; CHECK-NEXT: BLKSWAP 1, 4
 ; CHECK-NEXT: PUSH s4
@@ -108,7 +105,6 @@ entry:
 ; CHECK-NEXT:   JMPX
 ; CHECK-NEXT: }
 ; CHECK-NEXT: PUSHCONT {
-; CHECK-NEXT:   RET
 ; CHECK-NEXT: }
 ; CHECK-NEXT: BLKSWAP 2, 4
 ; CHECK-NEXT: PUSH s5

llvm/test/CodeGen/TVM/loops.ll

@@ -39,7 +39,6 @@ target triple = "tvm"
 ; CHECK-NEXT: PUSHCONT {
 ; CHECK-NEXT:   XCHG  s0, s2
 ; CHECK-NEXT:   BLKDROP 2
-; CHECK-NEXT:   RET
 ; CHECK-NEXT: }
 ; CHECK-NEXT: BLKSWAP 1, 4
 ; CHECK-NEXT: PUSH s4
@@ -101,7 +100,6 @@ for.body:
 ; CHECK-NEXT: PUSHCONT {
 ; CHECK-NEXT:   XCHG  s0, s2
 ; CHECK-NEXT:   BLKDROP 2
-; CHECK-NEXT:   RET
 ; CHECK-NEXT: }
 ; CHECK-NEXT: BLKSWAP 1, 4
 ; CHECK-NEXT: PUSH s4

llvm/tools/tvm-build/tvm-build++.py

@@ -143,6 +143,8 @@ def get_path(opt, optname, varname, default):
 else:
   opt_flags = ['-O3']
 
+opt_flags += ['-simplifycfg-dup-ret=1']
+
 _, bitcode_opt = tempfile.mkstemp()
 execute([os.path.join(tvm_llvm_bin, 'opt')] + opt_flags + [bitcode_int, '-o',
   bitcode_opt], args.verbose)

llvm/tools/tvm-build/tvm-build.py

@@ -152,6 +152,8 @@ def get_path(opt, optname, varname, default):
 else:
   opt_flags = ['-O3']
 
+opt_flags += ['-simplifycfg-dup-ret=1']
+
 _, bitcode_opt = tempfile.mkstemp()
 execute([os.path.join(tvm_llvm_bin, 'opt')] + opt_flags + [bitcode_int, '-o',
   bitcode_opt], args.verbose)