bool ARMConstantIslands::optimizeThumb2Branches() {
bool MadeChange = false;
- for (unsigned i = 0, e = ImmBranches.size(); i != e; ++i) {
- ImmBranch &Br = ImmBranches[i];
+ // The order in which branches appear in ImmBranches is approximately their
+ // order within the function body. By visiting later branches first, we reduce
+ // the distance between earlier forward branches and their targets, making it
+ // more likely that the cbn?z optimization, which can only apply to forward
+ // branches, will succeed.
+ for (unsigned i = ImmBranches.size(); i != 0; --i) {
+ ImmBranch &Br = ImmBranches[i-1];
unsigned Opcode = Br.MI->getOpcode();
unsigned NewOpc = 0;
unsigned Scale = 1;