GlobalISel: support selecting constants on AArch64.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@283806 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/AArch64/AArch64InstructionSelector.cpp

@@ -229,6 +229,16 @@ bool AArch64InstructionSelector::select(MachineInstr &I) const {
     return true;
   }
 
+  case TargetOpcode::G_CONSTANT: {
+    if (Ty.getSizeInBits() <= 32)
+      I.setDesc(TII.get(AArch64::MOVi32imm));
+    else if (Ty.getSizeInBits() <= 64)
+      I.setDesc(TII.get(AArch64::MOVi64imm));
+    else
+      return false;
+    return constrainSelectedInstRegOperands(I, TII, TRI, RBI);
+  }
+
   case TargetOpcode::G_FRAME_INDEX: {
     // allocas and G_FRAME_INDEX are only supported in addrspace(0).
     if (Ty != LLT::pointer(0, 64)) {

test/CodeGen/AArch64/GlobalISel/arm64-instructionselect.mir

@@ -67,6 +67,9 @@
 
   define void @selected_property() { ret void }
 
+  define i32 @const_s32() { ret i32 42 }
+  define i64 @const_s64() { ret i64 1234567890123 }
+
 ...
 
 ---
@@ -1088,3 +1091,33 @@ selected:        false
 body:             |
   bb.0:
 ...
+
+---
+# CHECK-LABEL: name: const_s32
+name:            const_s32
+legalized:       true
+regBankSelected: true
+registers:
+  - { id: 0, class: gpr }
+
+# CHECK:  body:
+# CHECK: %0 = MOVi32imm 42
+body:             |
+  bb.0:
+    %0(s32) = G_CONSTANT 42
+...
+
+---
+# CHECK-LABEL: name: const_s64
+name:            const_s64
+legalized:       true
+regBankSelected: true
+registers:
+  - { id: 0, class: gpr }
+
+# CHECK:  body:
+# CHECK: %0 = MOVi64imm 1234567890123
+body:             |
+  bb.0:
+    %0(s64) = G_CONSTANT 1234567890123
+...