[sil-combine] Enable switch_value to be optimized in OSSA.

This routine never touches values with non-trivial ownership, so I just removed
the early exit and updated the style.

Author: gottesmm

lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp

@@ -256,47 +256,46 @@ SILInstruction *SILCombiner::visitSelectEnumAddrInst(SelectEnumAddrInst *seai) {
   return eraseInstFromFunction(*seai);
 }
 
-SILInstruction *SILCombiner::visitSwitchValueInst(SwitchValueInst *SVI) {
-  if (SVI->getFunction()->hasOwnership())
+SILInstruction *SILCombiner::visitSwitchValueInst(SwitchValueInst *svi) {
+  SILValue cond = svi->getOperand();
+  BuiltinIntegerType *condTy = cond->getType().getAs<BuiltinIntegerType>();
+  if (!condTy || !condTy->isFixedWidth(1))
     return nullptr;
 
-  SILValue Cond = SVI->getOperand();
-  BuiltinIntegerType *CondTy = Cond->getType().getAs<BuiltinIntegerType>();
-  if (!CondTy || !CondTy->isFixedWidth(1))
-    return nullptr;
-
-  SILBasicBlock *FalseBB = nullptr;
-  SILBasicBlock *TrueBB = nullptr;
-  for (unsigned Idx = 0, Num = SVI->getNumCases(); Idx < Num; ++Idx) {
-    auto Case = SVI->getCase(Idx);
-    auto *CaseVal = dyn_cast<IntegerLiteralInst>(Case.first);
-    if (!CaseVal)
+  SILBasicBlock *falseBB = nullptr;
+  SILBasicBlock *trueBB = nullptr;
+  for (unsigned idx : range(svi->getNumCases())) {
+    auto switchCase = svi->getCase(idx);
+    auto *caseVal = dyn_cast<IntegerLiteralInst>(switchCase.first);
+    if (!caseVal)
       return nullptr;
-    SILBasicBlock *DestBB = Case.second;
-    assert(DestBB->args_empty() &&
+    SILBasicBlock *destBB = switchCase.second;
+    assert(destBB->args_empty() &&
            "switch_value case destination cannot take arguments");
-    if (CaseVal->getValue() == 0) {
-      assert(!FalseBB && "double case value 0 in switch_value");
-      FalseBB = DestBB;
+    if (caseVal->getValue() == 0) {
+      assert(!falseBB && "double case value 0 in switch_value");
+      falseBB = destBB;
     } else {
-      assert(!TrueBB && "double case value 1 in switch_value");
-      TrueBB = DestBB;
+      assert(!trueBB && "double case value 1 in switch_value");
+      trueBB = destBB;
     }
   }
-  if (SVI->hasDefault()) {
-    assert(SVI->getDefaultBB()->args_empty() &&
+
+  if (svi->hasDefault()) {
+    assert(svi->getDefaultBB()->args_empty() &&
            "switch_value default destination cannot take arguments");
-    if (!FalseBB) {
-      FalseBB = SVI->getDefaultBB();
-    } else if (!TrueBB) {
-      TrueBB = SVI->getDefaultBB();
+    if (!falseBB) {
+      falseBB = svi->getDefaultBB();
+    } else if (!trueBB) {
+      trueBB = svi->getDefaultBB();
     }
   }
-  if (!FalseBB || !TrueBB)
+
+  if (!falseBB || !trueBB)
     return nullptr;
 
-  Builder.setCurrentDebugScope(SVI->getDebugScope());
-  return Builder.createCondBranch(SVI->getLoc(), Cond, TrueBB, FalseBB);
+  Builder.setCurrentDebugScope(svi->getDebugScope());
+  return Builder.createCondBranch(svi->getLoc(), cond, trueBB, falseBB);
 }
 
 namespace {

test/SILOptimizer/sil_combine_ossa.sil

@@ -3681,9 +3681,10 @@ bb3(%16 : $Int32):                                  // Preds: bb1 bb2
   return %16 : $Int32                               // id: %17
 }
 
-// CHECK-LABEL: sil [ossa] @switch_value_to_cond_br_1
-// XHECK:      bb0({{.*}}):
-// XHECK-NEXT:   cond_br %0, bb1, bb2
+// CHECK-LABEL: sil [ossa] @switch_value_to_cond_br_1 :
+// CHECK:      bb0({{.*}}):
+// CHECK-NEXT:   cond_br %0, bb1, bb2
+// CHECK: } // end sil function 'switch_value_to_cond_br_1'
 sil [ossa] @switch_value_to_cond_br_1 : $@convention(thin) (Builtin.Int1) -> Int32 {
 bb0(%0 : $Builtin.Int1):
   %t1 = integer_literal $Builtin.Int1, -1
@@ -3703,9 +3704,10 @@ bb3(%16 : $Int32):                                  // Preds: bb1 bb2
   return %16 : $Int32                               // id: %17
 }
 
-// CHECK-LABEL: sil [ossa] @switch_value_to_cond_br_2
-// XHECK:      bb0({{.*}}):
-// XHECK-NEXT:   cond_br %0, bb2, bb1
+// CHECK-LABEL: sil [ossa] @switch_value_to_cond_br_2 :
+// CHECK:      bb0({{.*}}):
+// CHECK-NEXT:   cond_br %0, bb2, bb1
+// CHECK: } // end sil function 'switch_value_to_cond_br_2'
 sil [ossa] @switch_value_to_cond_br_2 : $@convention(thin) (Builtin.Int1) -> Int32 {
 bb0(%0 : $Builtin.Int1):
   %f1 = integer_literal $Builtin.Int1, 0
@@ -3725,9 +3727,10 @@ bb3(%16 : $Int32):                                  // Preds: bb1 bb2
   return %16 : $Int32                               // id: %17
 }
 
-// CHECK-LABEL: sil [ossa] @switch_value_to_cond_br_3
-// XHECK:      bb0({{.*}}):
-// XHECK-NEXT:   cond_br %0, bb1, bb2
+// CHECK-LABEL: sil [ossa] @switch_value_to_cond_br_3 :
+// CHECK:      bb0({{.*}}):
+// CHECK-NEXT:   cond_br %0, bb1, bb2
+// CHECK: } // end sil function 'switch_value_to_cond_br_3'
 sil [ossa] @switch_value_to_cond_br_3 : $@convention(thin) (Builtin.Int1) -> Int32 {
 bb0(%0 : $Builtin.Int1):
   %t1 = integer_literal $Builtin.Int1, -1