[CodeGen] Remove target SubRegLiveness flags (#95437)

This removes the uses of target flags to disable subreg liveness,
relying on the `-enable-subreg-liveness` flag instead. The
`-enable-subreg-liveness` flag has been changed to take precedence over
the subtarget if set, and one use of `Subtarget->enableSubRegLiveness()`
has been changed to `MRI->subRegLivenessEnabled()` to make sure the
option properly applies.

1 files changed, 1 insertions, 8 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCSubtarget.cpp b/llvm/lib/Target/PowerPC/PPCSubtarget.cpp
index 0628fbb..bd9af12 100644
--- a/llvm/lib/Target/PowerPC/PPCSubtarget.cpp
+++ b/llvm/lib/Target/PowerPC/PPCSubtarget.cpp
@@ -38,11 +38,6 @@ using namespace llvm;
 #include "PPCGenSubtargetInfo.inc"
 
 static cl::opt<bool>
-    UseSubRegLiveness("ppc-track-subreg-liveness",
-                      cl::desc("Enable subregister liveness tracking for PPC"),
-                      cl::init(true), cl::Hidden);
-
-static cl::opt<bool>
     EnableMachinePipeliner("ppc-enable-pipeliner",
                            cl::desc("Enable Machine Pipeliner for PPC"),
                            cl::init(false), cl::Hidden);
@@ -186,9 +181,7 @@ bool PPCSubtarget::useAA() const {
   return true;
 }
 
-bool PPCSubtarget::enableSubRegLiveness() const {
-  return UseSubRegLiveness;
-}
+bool PPCSubtarget::enableSubRegLiveness() const { return true; }
 
 bool PPCSubtarget::isGVIndirectSymbol(const GlobalValue *GV) const {
   if (isAIXABI()) {