Index: llvm/lib/Target/RISCV/RISCVInstrInfoF.td
===================================================================
--- llvm/lib/Target/RISCV/RISCVInstrInfoF.td
+++ llvm/lib/Target/RISCV/RISCVInstrInfoF.td
@@ -227,6 +227,12 @@
 def : InstAlias<"fscsr $rd, $rs", (CSRRW GPR:$rd, FCSR.Encoding, GPR:$rs)>;
 def : InstAlias<"fscsr $rs",      (CSRRW      X0, FCSR.Encoding, GPR:$rs), 2>;
 
+// frsr, fssr are obsolete aliases replaced by frcsr, fscsr, so give them
+// zero weight.
+def : InstAlias<"frsr $rd",       (CSRRS GPR:$rd, FCSR.Encoding, X0), 0>;
+def : InstAlias<"fssr $rd, $rs",  (CSRRW GPR:$rd, FCSR.Encoding, GPR:$rs), 0>;
+def : InstAlias<"fssr $rs",       (CSRRW      X0, FCSR.Encoding, GPR:$rs), 0>;
+
 def : InstAlias<"frrm $rd",        (CSRRS  GPR:$rd, FRM.Encoding, X0), 2>;
 def : InstAlias<"fsrm $rd, $rs",   (CSRRW  GPR:$rd, FRM.Encoding, GPR:$rs)>;
 def : InstAlias<"fsrm $rs",        (CSRRW       X0, FRM.Encoding, GPR:$rs), 2>;