[RISCV] Prefer li over pli in RISCVMatInt. (llvm#172778)

li is compressible, pli is not.

Author: topperc

llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp

@@ -79,7 +79,7 @@ static void generateInstSeqImpl(int64_t Val, const MCSubtargetInfo &STI,
     }
   }
 
-  if (STI.hasFeature(RISCV::FeatureStdExtP)) {
+  if (STI.hasFeature(RISCV::FeatureStdExtP) && !isInt<12>(Val)) {
     // Check if the immediate is packed i8 or i10
     int32_t Bit63To32 = Val >> 32;
     int32_t Bit31To0 = Val;

llvm/test/CodeGen/RISCV/rv32p.ll

@@ -25,3 +25,12 @@ define i64 @abs_i64(i64 %x) {
   %abs = tail call i64 @llvm.abs.i64(i64 %x, i1 true)
   ret i64 %abs
 }
+
+; Make sure we prefer li over pli
+define i32 @li_imm() {
+; CHECK-LABEL: li_imm:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    li a0, -1
+; CHECK-NEXT:    ret
+  ret i32 -1
+}

llvm/test/CodeGen/RISCV/rv64p.ll

@@ -38,3 +38,12 @@ define i64 @pack_i64_imm() {
 ; CHECK-NEXT:    ret
   ret i64 u0x0403020104030201
 }
+
+; Make sure we prefer li over pli
+define i64 @li_imm() {
+; CHECK-LABEL: li_imm:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    li a0, -1
+; CHECK-NEXT:    ret
+  ret i64 -1
+}