[globalisel][tablegen] Import SelectionDAG's rule predicates and support the equivalent in GIRule.

Summary:
The SelectionDAG importer now imports rules with Predicate's attached via
Requires, PredicateControl, etc. These predicates are implemented as
bitset's to allow multiple predicates to be tested together. However,
unlike the MC layer subtarget features, each target only pays for it's own
predicates (e.g. AArch64 doesn't have 192 feature bits just because X86
needs a lot).

Both AArch64 and X86 derive at least one predicate from the MachineFunction
or Function so they must re-initialize AvailableFeatures before each
function. They also declare locals in <Target>InstructionSelector so that
computeAvailableFeatures() can use the code from SelectionDAG without
modification.

Reviewers: rovka, qcolombet, aditya_nandakumar, t.p.northover, ab

Reviewed By: rovka

Subscribers: aemerson, rengolin, dberris, kristof.beyls, llvm-commits, igorb

Differential Revision: https://reviews.llvm.org/D31418

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300964 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 1 deletions

diff --git a/lib/Target/AArch64/AArch64InstructionSelector.cpp b/lib/Target/AArch64/AArch64InstructionSelector.cpp
index 5e01b6cd2b4..d2043823762 100644
--- a/lib/Target/AArch64/AArch64InstructionSelector.cpp
+++ b/lib/Target/AArch64/AArch64InstructionSelector.cpp
@@ -41,12 +41,17 @@ using namespace llvm;
 
 namespace {
 
+#define GET_GLOBALISEL_PREDICATE_BITSET
+#include "AArch64GenGlobalISel.inc"
+#undef GET_GLOBALISEL_PREDICATE_BITSET
+
 class AArch64InstructionSelector : public InstructionSelector {
 public:
   AArch64InstructionSelector(const AArch64TargetMachine &TM,
                              const AArch64Subtarget &STI,
                              const AArch64RegisterBankInfo &RBI);
 
+  void beginFunction(const MachineFunction &MF) override;
   bool select(MachineInstr &I) const override;
 
 private:
@@ -70,6 +75,12 @@ private:
   const AArch64InstrInfo &TII;
   const AArch64RegisterInfo &TRI;
   const AArch64RegisterBankInfo &RBI;
+  bool ForCodeSize;
+
+  PredicateBitset AvailableFeatures;
+  PredicateBitset
+  computeAvailableFeatures(const MachineFunction *MF,
+                           const AArch64Subtarget *Subtarget) const;
 
 // We declare the temporaries used by selectImpl() in the class to minimize the
 // cost of constructing placeholder values.
@@ -88,7 +99,7 @@ AArch64InstructionSelector::AArch64InstructionSelector(
     const AArch64TargetMachine &TM, const AArch64Subtarget &STI,
     const AArch64RegisterBankInfo &RBI)
     : InstructionSelector(), TM(TM), STI(STI), TII(*STI.getInstrInfo()),
-      TRI(*STI.getRegisterInfo()), RBI(RBI)
+      TRI(*STI.getRegisterInfo()), RBI(RBI), ForCodeSize(), AvailableFeatures()
 #define GET_GLOBALISEL_TEMPORARIES_INIT
 #include "AArch64GenGlobalISel.inc"
 #undef GET_GLOBALISEL_TEMPORARIES_INIT
@@ -567,6 +578,12 @@ bool AArch64InstructionSelector::selectVaStartDarwin(
   return true;
 }
 
+void AArch64InstructionSelector::beginFunction(
+    const MachineFunction &MF) {
+  ForCodeSize = MF.getFunction()->optForSize();
+  AvailableFeatures = computeAvailableFeatures(&MF, &STI);
+}
+
 bool AArch64InstructionSelector::select(MachineInstr &I) const {
   assert(I.getParent() && "Instruction should be in a basic block!");
   assert(I.getParent()->getParent() && "Instruction should be in a function!");