[RISCV] Fix RISCVTTIImpl::getIntImmCost for immediates where getMinSignedBits() > 64

[asb]

Summary

APInt::getSExtValue will assert if getMinSignedBits() > 64. This can happen, for instance, if examining an i128. Avoid this assertion by checking Imm.getMinSignedBits() <= 64 before doing getTLI()->isLegalAddImmediate(Imm.getSExtValue()). We could directly check getMinSignedBits() <= 12 but it seems better to reuse the isLegalAddImmediate helper for this.

[lenary]

Whoops, good catch.

llvm/trunk/lib/Target/RISCV/RISCVTargetTransformInfo.cpp

int RISCVTTIImpl::getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm,
   default:
     break;
   }
 
   if (Takes12BitImm) {
     // Check immediate is the correct argument...
     if (Instruction::isCommutative(Opcode) || Idx == ImmArgIdx) {
       // ... and fits into the 12-bit immediate.
-      if (getTLI()->isLegalAddImmediate(Imm.getSExtValue()))
+      if (Imm.getMinSignedBits() <= 64 &&
+          getTLI()->isLegalAddImmediate(Imm.getSExtValue())) {
         return TTI::TCC_Free;
       }
+    }
 
     // Otherwise, use the full materialisation cost.
     return getIntImmCost(Imm, Ty);
   }
 
   // By default, prevent hoisting.
   return TTI::TCC_Free;
 }
 
 int RISCVTTIImpl::getIntImmCost(Intrinsic::ID IID, unsigned Idx,
                                 const APInt &Imm, Type *Ty) {
   // Prevent hoisting in unknown cases.
   return TTI::TCC_Free;
 }

llvm/trunk/test/Transforms/ConstantHoisting/RISCV/immediates.ll

 
 ; Check that we hoist immediates with large values.
 define i64 @test3(i64 %a) nounwind {
 ; CHECK-LABEL: test3
 ; CHECK: %const = bitcast i64 32767 to i64
   %1 = mul i64 %a, 32767
   %2 = add i64 %1, 32767
   ret i64 %2
-}
+}
+
+; Check that we hoist immediates with very large values.
+define i128 @test4(i128 %a) nounwind {
+; CHECK-LABEL: test4
+; CHECK: %const = bitcast i128 12297829382473034410122878 to i128
+  %1 = add i128 %a, 12297829382473034410122878
+  %2 = add i128 %1, 12297829382473034410122878
+  ret i128 %2
+}