//
// This file implements the Jump Threading pass.
//
-// Jump threading tries to find distinct threads of control flow running through
-// a basic block. This pass looks at blocks that have multiple predecessors and
-// multiple successors. If one or more of the predecessors of the block can be
-// proven to always cause a jump to one of the successors, we forward the edge
-// from the predecessor to the successor by duplicating the contents of this
-// block.
-//
-// An example of when this can occur is code like this:
-//
-// if () { ...
-// X = 4;
-// }
-// if (X < 3) {
-//
-// In this case, the unconditional branch at the end of the first if can be
-// revectored to the false side of the second if.
-//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "jump-threading"
cl::init(6), cl::Hidden);
namespace {
+ /// This pass performs 'jump threading', which looks at blocks that have
+ /// multiple predecessors and multiple successors. If one or more of the
+ /// predecessors of the block can be proven to always jump to one of the
+ /// successors, we forward the edge from the predecessor to the successor by
+ /// duplicating the contents of this block.
+ ///
+ /// An example of when this can occur is code like this:
+ ///
+ /// if () { ...
+ /// X = 4;
+ /// }
+ /// if (X < 3) {
+ ///
+ /// In this case, the unconditional branch at the end of the first if can be
+ /// revectored to the false side of the second if.
+ ///
class VISIBILITY_HIDDEN JumpThreading : public FunctionPass {
public:
static char ID; // Pass identification