CodeGen: Redo analyzePhysRegs() and computeRegisterLiveness()

computeRegisterLiveness() was broken in that it reported dead for a
register even if a subregister was alive. I assume this was because the
results of analayzePhysRegs() are hard to understand with respect to
subregisters.

This commit: Changes the results of analyzePhysRegs (=struct
PhysRegInfo) to be clearly understandable, also renames the fields to
avoid silent breakage of third-party code (and improve the grammar).

Fix all (two) users of computeRegisterLiveness() in llvm: By reenabling
it and removing workarounds for the bug.

This fixes http://llvm.org/PR24535 and http://llvm.org/PR25033

Differential Revision: http://reviews.llvm.org/D15320

llvm-svn: 255362

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp b/llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
index b6c74244e64..920f4094a45 100644
--- a/llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
@@ -353,7 +353,7 @@ MachineInstr *SSACCmpConv::findConvertibleCompare(MachineBasicBlock *MBB) {
     MIOperands::PhysRegInfo PRI =
         MIOperands(I).analyzePhysReg(AArch64::NZCV, TRI);
 
-    if (PRI.Reads) {
+    if (PRI.Read) {
       // The ccmp doesn't produce exactly the same flags as the original
       // compare, so reject the transform if there are uses of the flags
       // besides the terminators.
@@ -362,7 +362,7 @@ MachineInstr *SSACCmpConv::findConvertibleCompare(MachineBasicBlock *MBB) {
       return nullptr;
     }
 
-    if (PRI.Clobbers) {
+    if (PRI.Defined || PRI.Clobbered) {
       DEBUG(dbgs() << "Not convertible compare: " << *I);
       ++NumUnknNZCVDefs;
       return nullptr;