MachineCombiner Pass for selecting faster instruction sequence on AArch64

Re-commit of r214832,r21469 with a work-around that
avoids the previous problem with gcc build compilers

The work-around is to use SmallVector instead of ArrayRef
of basic blocks in preservesResourceLen()/MachineCombiner.cpp

llvm-svn: 215151

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp b/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp
index 561bb24c6ab..7d7070c8c6e 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp
@@ -24,6 +24,10 @@ static cl::opt<bool>
 EnableCCMP("aarch64-ccmp", cl::desc("Enable the CCMP formation pass"),
            cl::init(true), cl::Hidden);
 
+static cl::opt<bool> EnableMCR("aarch64-mcr",
+                               cl::desc("Enable the machine combiner pass"),
+                               cl::init(true), cl::Hidden);
+
 static cl::opt<bool>
 EnableStPairSuppress("aarch64-stp-suppress", cl::desc("Suppress STP for AArch64"),
                      cl::init(true), cl::Hidden);
@@ -180,6 +184,8 @@ bool AArch64PassConfig::addInstSelector() {
 bool AArch64PassConfig::addILPOpts() {
   if (EnableCCMP)
     addPass(createAArch64ConditionalCompares());
+  if (EnableMCR)
+    addPass(&MachineCombinerID);
   if (EnableEarlyIfConversion)
     addPass(&EarlyIfConverterID);
   if (EnableStPairSuppress)