[SPARC] Implement hooks for conditional branch relaxation

Integrate the BranchRelaxation pass to help with relaxing out-of-range
conditional branches.

This is mostly of concern for SPARCv9, which uses conditional branches with
much smaller range than its v8 counterparts.
(Some large autogenerated code, such as the ones generated by TableGen, already
hits this limitation when building in Release)

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D142458

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/Target/Sparc/SparcTargetMachine.cpp b/llvm/lib/Target/Sparc/SparcTargetMachine.cpp
index 082bb44..577dc13 100644
--- a/llvm/lib/Target/Sparc/SparcTargetMachine.cpp
+++ b/llvm/lib/Target/Sparc/SparcTargetMachine.cpp
@@ -31,6 +31,10 @@ extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeSparcTarget() {
   initializeSparcDAGToDAGISelPass(PR);
 }
 
+static cl::opt<bool>
+    BranchRelaxation("sparc-enable-branch-relax", cl::Hidden, cl::init(true),
+                     cl::desc("Relax out of range conditional branches"));
+
 static std::string computeDataLayout(const Triple &T, bool is64Bit) {
   // Sparc is typically big endian, but some are little.
   std::string Ret = T.getArch() == Triple::sparcel ? "e" : "E";
@@ -181,6 +185,9 @@ bool SparcPassConfig::addInstSelector() {
 }
 
 void SparcPassConfig::addPreEmitPass(){
+  if (BranchRelaxation)
+    addPass(&BranchRelaxationPassID);
+
   addPass(createSparcDelaySlotFillerPass());
 
   if (this->getSparcTargetMachine().getSubtargetImpl()->insertNOPLoad())