[mips] Fix 'l' constraint handling for types smaller than 32 bits

In case of correct using of the 'l' constraint llvm now generates valid
code; otherwise it shows an error message. Initially these triggers an
assertion.

This commit is the same as r324869 with fixed the test's file name.

llvm-svn: 324885

llvm/lib/Target/Mips/MipsISelLowering.cpp

@@ -3868,7 +3868,7 @@ MipsTargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
       return std::make_pair(0U, nullptr);
     case 'l': // use the `lo` register to store values
               // that are no bigger than a word
-      if (VT == MVT::i32)
+      if (VT == MVT::i32 || VT == MVT::i16 || VT == MVT::i8)
         return std::make_pair((unsigned)Mips::LO0, &Mips::LO32RegClass);
       return std::make_pair((unsigned)Mips::LO0_64, &Mips::LO64RegClass);
     case 'x': // use the concatenated `hi` and `lo` registers

llvm/test/CodeGen/Mips/inlineasm-cnstrnt-bad-l1.ll

@@ -0,0 +1,13 @@
+; Negative test. The constraint 'l' represents the register 'lo'.
+; Check error message in case of invalid usage.
+;
+; RUN: not llc -march=mips -filetype=obj < %s 2>&1 | FileCheck %s
+
+define void @constraint_l() nounwind {
+entry:
+
+; CHECK: error: invalid operand for instruction
+
+  tail call i16 asm sideeffect "addiu $0,$1,$2", "=l,r,r,~{$1}"(i16 0, i16 0)
+  ret void
+}

llvm/test/CodeGen/Mips/inlineasm-cnstrnt-reg.ll

@@ -41,5 +41,15 @@ entry:
   call i32 asm sideeffect "\09mtlo $3 \0A\09\09madd $1, $2 ", "=l,r,r,r"(i32 7, i32 6, i32 44) nounwind
   store volatile i32 %4, i32* %bosco, align 4
  
+; Check the 'l' constraint for 16-bit type.
+; CHECK:       #APP
+; CHECK:       mtlo ${{[0-9]+}}
+; CHECK-NEXT:  madd ${{[0-9]+}}, ${{[0-9]+}}
+; CHECK:       #NO_APP
+; CHECK-NEXT:  mflo ${{[0-9]+}}
+  %bosco16 = alloca i16, align 4
+  call i16 asm sideeffect "\09mtlo $3 \0A\09\09madd $1, $2 ", "=l,r,r,r"(i32 7, i32 6, i32 44) nounwind
+  store volatile i16 %5, i16* %bosco16, align 4
+
   ret i32 0
 }