[PATCH] D28829: [thumb, framelowering] Reset NoVRegs in Thumb1FrameLowering::emitPrologue.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
Herald added a subscriber: rengolin.

In this function, virtual registers can be introduced (for example
through calls to emitThumbRegPlusImmInReg). doScavengeFrameVirtualRegs
will replace those virtual registers with concrete registers later on
in PrologEpilogInserter, which sets NoVRegs again.

This patch fixes the Codegen/Thumb/segmented-stacks.ll test case which
failed with expensive checks.
https://llvm.org/bugs/show_bug.cgi?id=27484


https://reviews.llvm.org/D28829

Files:
  lib/CodeGen/PrologEpilogInserter.cpp
  lib/Target/ARM/Thumb1FrameLowering.cpp


Index: lib/Target/ARM/Thumb1FrameLowering.cpp
===================================================================
--- lib/Target/ARM/Thumb1FrameLowering.cpp
+++ lib/Target/ARM/Thumb1FrameLowering.cpp
@@ -347,6 +347,10 @@
   // checks for hasVarSizedObjects.
   if (MFI.hasVarSizedObjects())
     AFI->setShouldRestoreSPFromFP(true);
+
+  // In some cases, virtual registers have been introduced, e.g. by uses of
+  // emitThumbRegPlusImmInReg.
+  MF.getProperties().reset(MachineFunctionProperties::Property::NoVRegs);
 }
 
 static bool isCSRestore(MachineInstr &MI, const MCPhysReg *CSRegs) {
Index: lib/CodeGen/PrologEpilogInserter.cpp
===================================================================
--- lib/CodeGen/PrologEpilogInserter.cpp
+++ lib/CodeGen/PrologEpilogInserter.cpp
@@ -1237,4 +1237,6 @@
         ++I;
     }
   }
+
+  MF.getProperties().set(MachineFunctionProperties::Property::NoVRegs);
 }


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