[RISCV] Increase complexity of RVV element extraction patterns

[• pcwang-thead]

Summary

Somehow some tests failed in our downstream because it matched
VFMV+FSD pattern first. Both FSD and VSE patterns have the same
complexity, while FSD is matched before VSE in the generated
matcher table.

This problem only occurs in our downstream (so sorry that I can't
provide a test here) and increasing the value of AddedComplexity
can fix it.

[StephenFan]

LGTM. But you probably want to wait for @craig.topper.

[craig.topper]

LGTM

llvm/lib/Target/RISCV/RISCVInstrInfoVSDPatterns.td

 //===----------------------------------------------------------------------===//
 // Vector Element Extracts
 //===----------------------------------------------------------------------===//
 let Predicates = [HasVInstructionsAnyF] in
 foreach vti = AllFloatVectors in {
   // Fold store of vmv.f.s to a vse with VL=1.
   defvar store_instr = !cast<Instruction>("PseudoVSE"#vti.SEW#"_V_"#vti.LMul.MX);
 
-  let AddedComplexity = 1 in {
+  let AddedComplexity = 2 in {
   // Add complexity to increase the priority of this pattern being matched.
   def : Pat<(store (vti.Scalar (int_riscv_vfmv_f_s (vti.Vector vti.RegClass:$rs2))), GPR:$rs1),
             (store_instr vti.RegClass:$rs2, GPR:$rs1, 1, vti.Log2SEW)>;
   def : Pat<(store (extractelt (vti.Vector vti.RegClass:$rs2), 0), GPR:$rs1),
             (store_instr vti.RegClass:$rs2, GPR:$rs1, 1, vti.Log2SEW)>;
   }
 
   defvar vmv_f_s_inst = !cast<Instruction>(!strconcat("PseudoVFMV_",
                                                        vti.ScalarSuffix,
                                                        "_S_", vti.LMul.MX));
   // Only pattern-match extract-element operations where the index is 0. Any
   // other index will have been custom-lowered to slide the vector correctly
   // into place.
   def : Pat<(vti.Scalar (extractelt (vti.Vector vti.RegClass:$rs2), 0)),
             (vmv_f_s_inst vti.RegClass:$rs2, vti.Log2SEW)>;
 }