TRI: Add hook to pass scavenger during frame elimination

The scavenger was not passed if requiresFrameIndexScavenging was
enabled. I need to be able to test for the availability of an
unallocatable register here, so I can't create a virtual register for
it.

It might be better to just always use the scavenger and stop
creating virtual registers.

llvm-svn: 287843

2 files changed, 12 insertions, 1 deletions

diff --git a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
index e833b2e9fb3..93c2060381d 100644
--- a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
@@ -182,6 +182,16 @@ SIRegisterInfo::requiresFrameIndexScavenging(const MachineFunction &MF) const {
   return MF.getFrameInfo().hasStackObjects();
 }
 
+bool SIRegisterInfo::requiresFrameIndexReplacementScavenging(
+  const MachineFunction &MF) const {
+  // m0 is needed for the scalar store offset. m0 is unallocatable, so we can't
+  // create a virtual register for it during frame index elimination, so the
+  // scavenger is directly needed.
+  return MF.getFrameInfo().hasStackObjects() &&
+         MF.getSubtarget<SISubtarget>().hasScalarStores() &&
+         MF.getInfo<SIMachineFunctionInfo>()->hasSpilledSGPRs();
+}
+
 bool SIRegisterInfo::requiresVirtualBaseRegisters(
   const MachineFunction &) const {
   // There are no special dedicated stack or frame pointers.
diff --git a/llvm/lib/Target/AMDGPU/SIRegisterInfo.h b/llvm/lib/Target/AMDGPU/SIRegisterInfo.h
index 72612aaab64..bd83ef1b403 100644
--- a/llvm/lib/Target/AMDGPU/SIRegisterInfo.h
+++ b/llvm/lib/Target/AMDGPU/SIRegisterInfo.h
@@ -50,8 +50,9 @@ public:
 
   bool requiresRegisterScavenging(const MachineFunction &Fn) const override;
 
-
   bool requiresFrameIndexScavenging(const MachineFunction &MF) const override;
+  bool requiresFrameIndexReplacementScavenging(
+    const MachineFunction &MF) const override;
   bool requiresVirtualBaseRegisters(const MachineFunction &Fn) const override;
   bool trackLivenessAfterRegAlloc(const MachineFunction &MF) const override;