[PPC] Use SeparateConstOffsetFromGEP
This mirrors r222331, which enabled SeparateConstOffsetFromGEP on AArch64, in
the PowerPC backend. Yields, on a POWER7 machine, a 30% speedup on
SingleSource/Benchmarks/Shootout/nestedloop (this might just be from LICM,
there is a store moved out of the inner loop) and a potential speedup on
MultiSource/Benchmarks/mediabench/mpeg2/mpeg2dec/mpeg2decode. Regardless, it
makes some code look cleaner, and synchronizing the backends in this regard
seems like a generally good thing.
llvm-svn: 222504
diff --git a/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp b/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
index f15189c..e930a9c 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
+++ b/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
@@ -22,6 +22,7 @@
#include "llvm/Support/FormattedStream.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Target/TargetOptions.h"
+#include "llvm/Transforms/Scalar.h"
using namespace llvm;
static cl::
@@ -32,6 +33,11 @@
VSXFMAMutateEarly("schedule-ppc-vsx-fma-mutation-early",
cl::Hidden, cl::desc("Schedule VSX FMA instruction mutation early"));
+static cl::opt<bool>
+EnableGEPOpt("ppc-gep-opt", cl::Hidden,
+ cl::desc("Enable optimizations on complex GEPs"),
+ cl::init(true));
+
extern "C" void LLVMInitializePowerPCTarget() {
// Register the targets
RegisterTargetMachine<PPC32TargetMachine> A(ThePPC32Target);
@@ -168,6 +174,20 @@
void PPCPassConfig::addIRPasses() {
addPass(createAtomicExpandPass(&getPPCTargetMachine()));
+
+ if (TM->getOptLevel() == CodeGenOpt::Aggressive && EnableGEPOpt) {
+ // Call SeparateConstOffsetFromGEP pass to extract constants within indices
+ // and lower a GEP with multiple indices to either arithmetic operations or
+ // multiple GEPs with single index.
+ addPass(createSeparateConstOffsetFromGEPPass(TM, true));
+ // Call EarlyCSE pass to find and remove subexpressions in the lowered
+ // result.
+ addPass(createEarlyCSEPass());
+ // Do loop invariant code motion in case part of the lowered result is
+ // invariant.
+ addPass(createLICMPass());
+ }
+
TargetPassConfig::addIRPasses();
}