[PATCH] D27192: TII: add hook analyzeLoopTestBlock

[Sjoerd Meijer via Phabricator via llvm-commits]

SjoerdMeijer created this revision.
SjoerdMeijer added reviewers: jmolloy, bcahoon, kparzysz, qcolombet.
SjoerdMeijer added a subscriber: llvm-commits.

TII: add hook analyzeLoopTestBlock. This is refactored from the Hexagon backend and is intended to be NFC. This is some more groundwork to recognise loop induction variables and trip counts for MachineLoops, and is related to https://reviews.llvm.org/D27191.


https://reviews.llvm.org/D27192

Files:
  include/llvm/Target/TargetInstrInfo.h
  lib/Target/Hexagon/HexagonInstrInfo.cpp
  lib/Target/Hexagon/HexagonInstrInfo.h


Index: lib/Target/Hexagon/HexagonInstrInfo.h
===================================================================
--- lib/Target/Hexagon/HexagonInstrInfo.h
+++ lib/Target/Hexagon/HexagonInstrInfo.h
@@ -248,6 +248,11 @@
   CreateTargetPostRAHazardRecognizer(const InstrItineraryData*,
                                      const ScheduleDAG *DAG) const override;
 
+  /// Returns true when MB contains a compare with an immediate value
+  bool analyzeLoopTestBlock(MachineBasicBlock &MB, unsigned &CmpReg1,
+                            unsigned &CmpReg2, int &CmpMask,
+                            int &CmpImm) const override;
+
   /// For a comparison instruction, return the source registers
   /// in SrcReg and SrcReg2 if having two register operands, and the value it
   /// compares against in CmpValue. Return true if the comparison instruction
Index: lib/Target/Hexagon/HexagonInstrInfo.cpp
===================================================================
--- lib/Target/Hexagon/HexagonInstrInfo.cpp
+++ lib/Target/Hexagon/HexagonInstrInfo.cpp
@@ -1513,6 +1513,37 @@
   return TargetInstrInfo::CreateTargetPostRAHazardRecognizer(II, DAG);
 }
 
+///  return the source registers in
+/// \p SrcReg and \p SrcReg2 if having two register operands, and the value it
+/// compares against in CmpValue. Return true if the comparison instruction
+/// can be analyzed.
+bool HexagonInstrInfo::analyzeLoopTestBlock(MachineBasicBlock &MB,
+                                            unsigned &CmpReg1,
+                                            unsigned &CmpReg2,
+                                            int &CmpMask, int &CmpImm) const {
+  SmallVector<MachineOperand,2> Cond;
+  MachineBasicBlock *TB = nullptr, *FB = nullptr;
+  bool NotAnalyzed = analyzeBranch(MB, TB, FB, Cond, false);
+  if (NotAnalyzed)
+    return false;
+
+  unsigned PredR, PredPos, PredRegFlags;
+  if (!getPredReg(Cond, PredR, PredPos, PredRegFlags))
+    return false;
+
+  MachineRegisterInfo &MRI = MB.getParent()->getRegInfo();
+  MachineInstr *PredI = MRI.getVRegDef(PredR);
+  if (!PredI->isCompare())
+    return false;
+
+  // Fail if the compare was not analyzed, or it's not comparing a register
+  // with an immediate value.  Not checking the mask here, since we handle
+  // the individual compare opcodes (including A4_cmpb*) later on.
+  if (!analyzeCompare(*PredI, CmpReg1, CmpReg2, CmpMask, CmpImm))
+    return false;
+
+  return true;
+}
 
 /// \brief For a comparison instruction, return the source registers in
 /// \p SrcReg and \p SrcReg2 if having two register operands, and the value it
Index: include/llvm/Target/TargetInstrInfo.h
===================================================================
--- include/llvm/Target/TargetInstrInfo.h
+++ include/llvm/Target/TargetInstrInfo.h
@@ -586,6 +586,16 @@
                         ArrayRef<MachineOperand>(), DL, BytesAdded);
   }
 
+  /// For a machine block that contains the loop thest, return the source
+  /// registers of the loop test in SrcReg and SrcReg2 if having two register
+  /// operands, and the value it compares against in CmpValue. Return true if
+  /// the comparison instruction can be analyzed.
+  virtual bool analyzeLoopTestBlock(MachineBasicBlock &MB, unsigned &CmpReg1,
+                                    unsigned &CmpReg2, int &CmpMask,
+                                    int &CmpImm) const {
+    return false;
+  }
+
   /// Analyze the loop code, return true if it cannot be understoo. Upon
   /// success, this function returns false and returns information about the
   /// induction variable and compare instruction used at the end.


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