[clang] [llvm] [SystemZ] Global Stackprotector and associated location section (PR #169317)

[Dominik Steenken via cfe-commits]

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@@ -1805,15 +1777,141 @@ bool SystemZInstrInfo::expandPostRAPseudo(MachineInstr &MI) const {
     splitAdjDynAlloc(MI);
     return true;
 
-  case TargetOpcode::LOAD_STACK_GUARD:
-    expandLoadStackGuard(&MI);
+  case SystemZ::MOVE_STACK_GUARD:
+    expandMSGPseudo(MI);
+    return true;
+
+  case SystemZ::COMPARE_STACK_GUARD:
+    expandCSGPseudo(MI);
     return true;
 
   default:
     return false;
   }
 }
 
+namespace {
+Register scavengeAddrReg(MachineInstr &MI, MachineBasicBlock *MBB) {
+  // create fresh RegScavanger instance.
+  RegScavenger RS;
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dominik-steenken wrote:

I have a tentative implementation of this, in commit 652aa771 . It instantiates the `RegScavenger` in the `run` method of the `ExpandPostRAPseudos` pass. I am a bit unsure about this, since the pass goes over MBBs in-order, while the `RS` needs to consider the instructions in reverse, leading to the loop calling `enterBasicBlockEnd` for every `MI`, which seems wrong?

https://github.com/llvm/llvm-project/pull/169317