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

fhahn · fhahn · commit 8485cecd3f48 · 2017-01-18T15:01:22.000Z
Summary: 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 Reviewers: rnk, bkramer, olista01 Reviewed By: olista01 Subscribers: llvm-commits, rengolin Differential Revision: https://reviews.llvm.org/D28829 llvm-svn: 292372
diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -1237,4 +1237,6 @@ doScavengeFrameVirtualRegs(MachineFunction &MF, RegScavenger *RS) {
         ++I;
     }
   }
+
+  MF.getProperties().set(MachineFunctionProperties::Property::NoVRegs);
 }
diff --git a/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp b/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp
@@ -347,6 +347,10 @@ void Thumb1FrameLowering::emitPrologue(MachineFunction &MF,
   // 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) {

Original file line number	Diff line number	Diff line change
`@@ -1237,4 +1237,6 @@ doScavengeFrameVirtualRegs(MachineFunction &MF, RegScavenger *RS) {`
`1237`	`1237`	`++I;`
`1238`	`1238`	`}`
`1239`	`1239`	`}`
	`1240`	`+`
	`1241`	`+ MF.getProperties().set(MachineFunctionProperties::Property::NoVRegs);`
`1240`	`1242`	`}`