[RISCV] Use Predicates instead of Added Complexity to prefer QC_SELECTEQI over QC_MVEQI. NFC #148312
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…TEQI 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.
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@llvm/pr-subscribers-backend-risc-v Author: Craig Topper (topperc) ChangesIMHO AddedComplexity should be used as a last resort. We should use other mechanism like Predicates and PatFrag predicates to give priority. Full diff: https://github.com/llvm/llvm-project/pull/148312.diff 2 Files Affected:
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>;
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lenary
approved these changes
Jul 12, 2025
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IMHO AddedComplexity should be used as a last resort. We should use other mechanism like Predicates and PatFrag predicates to give priority.