Add a -regalloc=default option that chooses a register allocator based on the -O
optimization level.
This only really affects llc for now because both the llvm-gcc and clang front
ends override the default register allocator. I intend to remove that code later.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104904 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp
index b584704..7f1a7c4 100644
--- a/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/lib/CodeGen/LLVMTargetMachine.cpp
@@ -358,7 +358,7 @@
/* allowDoubleDefs= */ true);
// Perform register allocation.
- PM.add(createRegisterAllocator());
+ PM.add(createRegisterAllocator(OptLevel));
printAndVerify(PM, "After Register Allocation");
// Perform stack slot coloring and post-ra machine LICM.
diff --git a/lib/CodeGen/Passes.cpp b/lib/CodeGen/Passes.cpp
index 5ea2941..09123fe 100644
--- a/lib/CodeGen/Passes.cpp
+++ b/lib/CodeGen/Passes.cpp
@@ -24,6 +24,11 @@
//===---------------------------------------------------------------------===//
MachinePassRegistry RegisterRegAlloc::Registry;
+static FunctionPass *createDefaultRegisterAllocator() { return 0; }
+static RegisterRegAlloc
+defaultRegAlloc("default",
+ "pick register allocator based on -O option",
+ createDefaultRegisterAllocator);
//===---------------------------------------------------------------------===//
///
@@ -33,8 +38,8 @@
static cl::opt<RegisterRegAlloc::FunctionPassCtor, false,
RegisterPassParser<RegisterRegAlloc> >
RegAlloc("regalloc",
- cl::init(&createLinearScanRegisterAllocator),
- cl::desc("Register allocator to use (default=linearscan)"));
+ cl::init(&createDefaultRegisterAllocator),
+ cl::desc("Register allocator to use"));
//===---------------------------------------------------------------------===//
@@ -42,13 +47,22 @@
/// createRegisterAllocator - choose the appropriate register allocator.
///
//===---------------------------------------------------------------------===//
-FunctionPass *llvm::createRegisterAllocator() {
+FunctionPass *llvm::createRegisterAllocator(CodeGenOpt::Level OptLevel) {
RegisterRegAlloc::FunctionPassCtor Ctor = RegisterRegAlloc::getDefault();
-
+
if (!Ctor) {
Ctor = RegAlloc;
RegisterRegAlloc::setDefault(RegAlloc);
}
-
- return Ctor();
+
+ if (Ctor != createDefaultRegisterAllocator)
+ return Ctor();
+
+ // When the 'default' allocator is requested, pick one based on OptLevel.
+ switch (OptLevel) {
+ case CodeGenOpt::None:
+ return createLocalRegisterAllocator();
+ default:
+ return createLinearScanRegisterAllocator();
+ }
}