Commit 8e554281 authored by Hans Wennborg's avatar Hans Wennborg
Browse files

Merging r276361: 

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r276361 | wolfgangp | 2016-07-21 16:28:18 -0700 (Thu, 21 Jul 2016) | 5 lines

Reverting r275115 which caused PR28634.
When empty (forwarding) basic blocks that are referenced by user labels
are removed, incorrect code may be generated.


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llvm-svn: 276656
parent 76fe58b1

clang/lib/CodeGen/CGStmt.cpp

+1 −13
Original line number Diff line number Diff line
@@ -620,14 +620,7 @@ void CodeGenFunction::EmitIfStmt(const IfStmt &S) { 
    RunCleanupsScope ThenScope(*this);

    EmitStmt(S.getThen());

  }

  {

    auto CurBlock = Builder.GetInsertBlock();

  EmitBranch(ContBlock);

    // Eliminate any empty blocks that may have been created by nested

    // control flow statements in the 'then' clause.

    if (CurBlock)

      SimplifyForwardingBlocks(CurBlock); 

  }



  // Emit the 'else' code if present.

  if (const Stmt *Else = S.getElse()) {
@@ -643,12 +636,7 @@ void CodeGenFunction::EmitIfStmt(const IfStmt &S) { 
    {

      // There is no need to emit line number for an unconditional branch.

      auto NL = ApplyDebugLocation::CreateEmpty(*this);

      auto CurBlock = Builder.GetInsertBlock();

      EmitBranch(ContBlock);

      // Eliminate any empty blocks that may have been created by nested

      // control flow statements emitted in the 'else' clause.

      if (CurBlock)

        SimplifyForwardingBlocks(CurBlock); 

    }

  }

clang/test/CodeGen/forwarding-blocks-if.c

deleted100644 → 0
+0 −36
Original line number Diff line number Diff line 
// RUN: %clang_cc1 %s -emit-llvm -o - | FileCheck %s

// Check that no empty blocks are generated for nested ifs.



extern void func();



int f0(int val) {

  if (val == 0) {

    func();

  } else if (val == 1) {

    func();

  }

  return 0;

}



// CHECK-LABEL: define {{.*}}i32 @f0

// CHECK: call void {{.*}} @func

// CHECK: call void {{.*}} @func

// CHECK: br label %[[RETBLOCK1:[^ ]*]]

// CHECK: [[RETBLOCK1]]:

// CHECK-NOT: br label

// CHECK: ret i32



int f1(int val, int g) {

  if (val == 0)

    if (g == 1) {

      func();

    }

  return 0;

}



// CHECK-LABEL: define {{.*}}i32 @f1

// CHECK: call void {{.*}} @func

// CHECK: br label %[[RETBLOCK2:[^ ]*]]

// CHECK: [[RETBLOCK2]]:

// CHECK-NOT: br label

// CHECK: ret i32