[CodeGen] Add -align-loops

to `lib/CodeGen/CommandFlags.cpp`. It can replace
-x86-experimental-pref-loop-alignment=.

The loop alignment is only used by MachineBlockPlacement.
The implementation uses a new `llvm::TargetOptions` for now, as
an IR function attribute/module flags metadata may be overkill.

This is the llvm part of D106701.

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/CommandFlags.cpp b/llvm/lib/CodeGen/CommandFlags.cpp
index f3cba62..e5f5da5 100644
--- a/llvm/lib/CodeGen/CommandFlags.cpp
+++ b/llvm/lib/CodeGen/CommandFlags.cpp
@@ -94,6 +94,7 @@ CGOPT(bool, ValueTrackingVariableLocations)
 CGOPT(bool, ForceDwarfFrameSection)
 CGOPT(bool, XRayOmitFunctionIndex)
 CGOPT(bool, DebugStrictDwarf)
+CGOPT(unsigned, AlignLoops)
 
 codegen::RegisterCodeGenFlags::RegisterCodeGenFlags() {
 #define CGBINDOPT(NAME)                                                        \
@@ -452,6 +453,10 @@ codegen::RegisterCodeGenFlags::RegisterCodeGenFlags() {
       "strict-dwarf", cl::desc("use strict dwarf"), cl::init(false));
   CGBINDOPT(DebugStrictDwarf);
 
+  static cl::opt<unsigned> AlignLoops("align-loops",
+                                      cl::desc("Default alignment for loops"));
+  CGBINDOPT(AlignLoops);
+
 #undef CGBINDOPT
 
   mc::RegisterMCTargetOptionsFlags();
@@ -527,6 +532,7 @@ codegen::InitTargetOptionsFromCodeGenFlags(const Triple &TheTriple) {
   Options.ForceDwarfFrameSection = getForceDwarfFrameSection();
   Options.XRayOmitFunctionIndex = getXRayOmitFunctionIndex();
   Options.DebugStrictDwarf = getDebugStrictDwarf();
+  Options.LoopAlignment = getAlignLoops();
 
   Options.MCOptions = mc::InitMCTargetOptionsFromFlags();