[Lanai] implement wide immediate support

This fixes LanaiTTIImpl::getIntImmCost to return valid costs for i128
(and wider) values. Previously any immediate wider than
64 bits would cause Lanai llc to crash.

A regression test is also added that exercises this functionality.

Reviewed By: jpienaar

Differential Revision: https://reviews.llvm.org/D107091

llvm/lib/Target/Lanai/LanaiTargetTransformInfo.h

@@ -52,6 +52,16 @@ public:
   InstructionCost getIntImmCost(const APInt &Imm, Type *Ty,
                                 TTI::TargetCostKind CostKind) {
     assert(Ty->isIntegerTy());
+    unsigned BitSize = Ty->getPrimitiveSizeInBits();
+    // There is no cost model for constants with a bit size of 0. Return
+    // TCC_Free here, so that constant hoisting will ignore this constant.
+    if (BitSize == 0)
+      return TTI::TCC_Free;
+    // No cost model for operations on integers larger than 64 bit implemented
+    // yet.
+    if (BitSize > 64)
+      return TTI::TCC_Free;
+
     if (Imm == 0)
       return TTI::TCC_Free;
     if (isInt<16>(Imm.getSExtValue()))

llvm/test/CodeGen/Lanai/lowering-128.ll

@@ -11,3 +11,12 @@ define i128 @add128(i128 %x, i128 %y) {
   %a = add i128 %x, %y
   ret i128 %a
 }
+
+; CHECK-LABEL: immshift128:
+define i128 @immshift128(i1 %sel) unnamed_addr {
+  %a = add i128 0, 340282366920938463463374007431768209319
+  %b = add i128 0, 340282366920938463463374607431768209320
+  %c = select i1 %sel, i128 %a, i128 %b
+  %d = shl i128 %a, 10
+  ret i128 %d
+}