Enable SimplifyCFG::simplifyTermWithIdenticalDestBlocks for OSSA

Author: meg-gupta

lib/SILOptimizer/Transforms/SimplifyCFG.cpp

@@ -2535,15 +2535,6 @@ bool SimplifyCFG::simplifyTermWithIdenticalDestBlocks(SILBasicBlock *BB) {
     return false;
   }
   TermInst *Term = BB->getTerminator();
-  // TODO: OSSA; cleanup nontrivial terminator operands (if this ever actually
-  // happens)
-  if (!EnableOSSARewriteTerminator && Fn.hasOwnership()) {
-    if (llvm::any_of(Term->getOperandValues(), [this](SILValue op) {
-          return !op->getType().isTrivial(Fn);
-        })) {
-      return false;
-    }
-  }
   LLVM_DEBUG(llvm::dbgs() << "replace term with identical dests: " << *Term);
   SILBuilderWithScope(Term).createBranch(Term->getLoc(), commonDest.destBB,
                                          commonDest.newSourceBranchArgs);

lib/SILOptimizer/UtilityPasses/UnitTestRunner.cpp

@@ -309,6 +309,19 @@ struct SimplifyCFGSimplifySwitchEnumUnreachableBlocks : UnitTest {
   }
 };
 
+struct SimplifyCFGSimplifyTermWithIdenticalDestBlocks : UnitTest {
+  SimplifyCFGSimplifyTermWithIdenticalDestBlocks(UnitTestRunner *pass)
+      : UnitTest(pass) {}
+  void invoke(Arguments &arguments) override {
+    auto *passToRun = cast<SILFunctionTransform>(createSimplifyCFG());
+    passToRun->injectPassManager(getPass()->getPassManager());
+    passToRun->injectFunction(getFunction());
+    SimplifyCFG(*getFunction(), *passToRun, /*VerifyAll=*/false,
+                /*EnableJumpThread=*/false)
+        .simplifyTermWithIdenticalDestBlocks(arguments.takeBlock());
+  }
+};
+
 // Arguments:
 // - string: list of characters, each of which specifies subsequent arguments
 //           - A: (block) argument
@@ -438,6 +451,9 @@ void UnitTestRunner::withTest(StringRef name, Doit doit) {
     ADD_UNIT_TEST_SUBCLASS(
         "simplify-cfg-simplify-switch-enum-unreachable-blocks",
         SimplifyCFGSimplifySwitchEnumUnreachableBlocks)
+    ADD_UNIT_TEST_SUBCLASS(
+        "simplify-cfg-simplify-term-with-identical-dest-blocks",
+        SimplifyCFGSimplifyTermWithIdenticalDestBlocks)
 
     ADD_UNIT_TEST_SUBCLASS("test-specification-parsing", TestSpecificationTest)
     ADD_UNIT_TEST_SUBCLASS("visit-adjacent-reborrows-of-phi", VisitAdjacentReborrowsOfPhiTest)

test/SILOptimizer/simplify_cfg_ossa_simplify_branch.sil

@@ -45,3 +45,39 @@ bb6:
   inject_enum_addr %0 : $*FakeOptional<Klass>, #FakeOptional.none!enumelt
   br bb5
 }
+
+enum E1<T> {
+  case some1(T)
+  case some2(T)
+}
+
+sil [ossa] @test_simplify_term_with_identical_dest_blocks1 : $@convention(thin) (@owned Klass) -> () {
+bb0(%0 : @owned $Klass):
+  test_specification "simplify-cfg-simplify-term-with-identical-dest-blocks @block[0]"
+  %1 = begin_borrow %0 : $Klass
+  br bb1(%1 : $Klass)
+
+bb1(%3 : @guaranteed $Klass):
+  br bb2(%3 : $Klass)
+
+bb2(%5 : @guaranteed $Klass):
+  end_borrow %5 : $Klass
+  destroy_value %0 : $Klass
+  %t = tuple ()
+  return %t : $()
+}
+
+sil [ossa] @test_simplify_term_with_identical_dest_blocks2 : $@convention(thin) (@owned Klass) -> () {
+bb0(%0 : @owned $Klass):
+  test_specification "simplify-cfg-simplify-term-with-identical-dest-blocks @block[0]"
+  br bb1(%0 : $Klass)
+
+bb1(%3 : @owned $Klass):
+  br bb2(%3 : $Klass)
+
+bb2(%5 : @owned $Klass):
+  destroy_value %5 : $Klass
+  %t = tuple ()
+  return %t : $()
+}
+