[GlobalISel][X86] G_ICMP support.

Summary: support G_ICMP for scalar types i8/i16/i64.

Reviewers: zvi, guyblank

Reviewed By: guyblank

Subscribers: rovka, kristof.beyls, llvm-commits, krytarowski

Differential Revision: https://reviews.llvm.org/D32995

llvm-svn: 302774

2 files changed, 69 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86InstructionSelector.cpp b/llvm/lib/Target/X86/X86InstructionSelector.cpp
index 2ec89379674..25d7785b71f 100644
--- a/llvm/lib/Target/X86/X86InstructionSelector.cpp
+++ b/llvm/lib/Target/X86/X86InstructionSelector.cpp
@@ -73,6 +73,8 @@ private:
                    MachineFunction &MF) const;
   bool selectZext(MachineInstr &I, MachineRegisterInfo &MRI,
                   MachineFunction &MF) const;
+  bool selectCmp(MachineInstr &I, MachineRegisterInfo &MRI,
+                 MachineFunction &MF) const;
 
   const X86TargetMachine &TM;
   const X86Subtarget &STI;
@@ -245,6 +247,8 @@ bool X86InstructionSelector::select(MachineInstr &I) const {
     return true;
   if (selectZext(I, MRI, MF))
     return true;
+  if (selectCmp(I, MRI, MF))
+    return true;
 
   return false;
 }
@@ -612,6 +616,59 @@ bool X86InstructionSelector::selectZext(MachineInstr &I,
   return false;
 }
 
+bool X86InstructionSelector::selectCmp(MachineInstr &I,
+                                       MachineRegisterInfo &MRI,
+                                       MachineFunction &MF) const {
+  if (I.getOpcode() != TargetOpcode::G_ICMP)
+    return false;
+
+  X86::CondCode CC;
+  bool SwapArgs;
+  std::tie(CC, SwapArgs) = X86::getX86ConditionCode(
+      (CmpInst::Predicate)I.getOperand(1).getPredicate());
+  unsigned OpSet = X86::getSETFromCond(CC);
+
+  unsigned LHS = I.getOperand(2).getReg();
+  unsigned RHS = I.getOperand(3).getReg();
+
+  if (SwapArgs)
+    std::swap(LHS, RHS);
+
+  unsigned OpCmp;
+  LLT Ty = MRI.getType(LHS);
+
+  switch (Ty.getSizeInBits()) {
+  default:
+    return false;
+  case 8:
+    OpCmp = X86::CMP8rr;
+    break;
+  case 16:
+    OpCmp = X86::CMP16rr;
+    break;
+  case 32:
+    OpCmp = X86::CMP32rr;
+    break;
+  case 64:
+    OpCmp = X86::CMP64rr;
+    break;
+  }
+
+  MachineInstr &CmpInst =
+      *BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(OpCmp))
+           .addReg(LHS)
+           .addReg(RHS);
+
+  MachineInstr &SetInst = *BuildMI(*I.getParent(), I, I.getDebugLoc(),
+                                   TII.get(OpSet), I.getOperand(0).getReg());
+
+  constrainSelectedInstRegOperands(CmpInst, TII, TRI, RBI);
+  constrainSelectedInstRegOperands(SetInst, TII, TRI, RBI);
+
+  I.eraseFromParent();
+  return true;
+}
+
 InstructionSelector *
 llvm::createX86InstructionSelector(const X86TargetMachine &TM,
                                    X86Subtarget &Subtarget,
diff --git a/llvm/lib/Target/X86/X86LegalizerInfo.cpp b/llvm/lib/Target/X86/X86LegalizerInfo.cpp
index 0849ea98c31..cf26238c023 100644
--- a/llvm/lib/Target/X86/X86LegalizerInfo.cpp
+++ b/llvm/lib/Target/X86/X86LegalizerInfo.cpp
@@ -91,6 +91,12 @@ void X86LegalizerInfo::setLegalizerInfo32bit() {
     setAction({G_ZEXT, 1, Ty}, Legal);
     setAction({G_SEXT, 1, Ty}, Legal);
   }
+
+  // Comparison
+  setAction({G_ICMP, s1}, Legal);
+
+  for (auto Ty : {s8, s16, s32, p0})
+    setAction({G_ICMP, 1, Ty}, Legal);
 }
 
 void X86LegalizerInfo::setLegalizerInfo64bit() {
@@ -143,6 +149,12 @@ void X86LegalizerInfo::setLegalizerInfo64bit() {
     setAction({G_ZEXT, 1, Ty}, Legal);
     setAction({G_SEXT, 1, Ty}, Legal);
   }
+
+  // Comparison
+  setAction({G_ICMP, s1}, Legal);
+
+  for (auto Ty : {s8, s16, s32, s64, p0})
+    setAction({G_ICMP, 1, Ty}, Legal);
 }
 
 void X86LegalizerInfo::setLegalizerInfoSSE1() {