[llvm] [RISCV] Use Predicates instead of Added Complexity to prefer QC_SELECTEQI over QC_MVEQI. NFC (PR #148312)

[Craig Topper via llvm-commits]

https://github.com/topperc created https://github.com/llvm/llvm-project/pull/148312

IMHO AddedComplexity should be used as a last resort. We should use other mechanism like Predicates and PatFrag predicates to give priority.

>From a454651c3946fd8e59665dfd2bb4402a9ba749c4 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Fri, 11 Jul 2025 15:40:46 -0700
Subject: [PATCH] [RISCV] Use Predicates instead of Added Complexity to prefer
 QC_SELECTEQI over QC_MVEQI. NFC

IMHO AddedComplexity should be used as a last resort. We should
use other mechanism like Predicates and PatFrag predicates to give
priority.
---
 llvm/lib/Target/RISCV/RISCVFeatures.td      |  2 ++
 llvm/lib/Target/RISCV/RISCVInstrInfoXqci.td | 12 ++++++------
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVFeatures.td b/llvm/lib/Target/RISCV/RISCVFeatures.td
index bf58226e0bd39..f74f1e06d66a2 100644
--- a/llvm/lib/Target/RISCV/RISCVFeatures.td
+++ b/llvm/lib/Target/RISCV/RISCVFeatures.td
@@ -1487,6 +1487,8 @@ def HasVendorXqcics
     : Predicate<"Subtarget->hasVendorXqcics()">,
       AssemblerPredicate<(all_of FeatureVendorXqcics),
                          "'Xqcics' (Qualcomm uC Conditional Select Extension)">;
+def NoVendorXqcics
+    : Predicate<"!Subtarget->hasVendorXqcics()">;
 
 def FeatureVendorXqcicsr
     : RISCVExperimentalExtension<0, 4, "Qualcomm uC CSR Extension">;
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoXqci.td b/llvm/lib/Target/RISCV/RISCVInstrInfoXqci.td
index 9e3eb1c03fb37..afb11998e9277 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoXqci.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoXqci.td
@@ -1484,12 +1484,16 @@ def : QCIMVCCPat <SETNE,  QC_MVNE>;
 def : QCIMVCCPat <SETLT,  QC_MVLT>;
 def : QCIMVCCPat <SETULT, QC_MVLTU>;
 
-def : QCIMVCCIPat <SETEQ,  QC_MVEQI, simm5>;
-def : QCIMVCCIPat <SETNE,  QC_MVNEI, simm5>;
 def : QCIMVCCIPat <SETLT,  QC_MVLTI, simm5>;
 def : QCIMVCCIPat <SETULT, QC_MVLTUI, uimm5>;
 }
 
+// Prioritize Xqcics over these patterns.
+let Predicates = [HasVendorXqcicm, NoVendorXqcics, IsRV32] in {
+def : QCIMVCCIPat <SETEQ,  QC_MVEQI, simm5>;
+def : QCIMVCCIPat <SETNE,  QC_MVNEI, simm5>;
+}
+
 let Predicates = [HasVendorXqcics, IsRV32] in {
 def : Pat<(select (XLenVT GPRNoX0:$rd), (XLenVT GPRNoX0:$rs2),(XLenVT GPRNoX0:$rs3)),
           (QC_SELECTNEI GPRNoX0:$rd, (XLenVT 0), GPRNoX0:$rs2, GPRNoX0:$rs3)>;
@@ -1498,12 +1502,8 @@ def : Pat<(select (XLenVT GPRNoX0:$rd), (XLenVT GPRNoX0:$rs2), simm5:$simm2),
 def : Pat<(select (XLenVT GPRNoX0:$rd), simm5:$simm2,(XLenVT GPRNoX0:$rs2)),
           (QC_SELECTIEQI GPRNoX0:$rd, (XLenVT 0), GPRNoX0:$rs2, simm5:$simm2)>;
 
-// Below AddedComplexity is added to prefer these conditional select instructions over
-// conditional move instructions
-let AddedComplexity = 1 in {
 def : QCISELECTCCIPat <SETEQ,  QC_SELECTEQI>;
 def : QCISELECTCCIPat <SETNE,  QC_SELECTNEI>;
-}
 
 def : QCISELECTICCIPat <SETEQ,  QC_SELECTIEQI>;
 def : QCISELECTICCIPat <SETNE,  QC_SELECTINEI>;