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

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topperc merged 1 commit intollvm:mainfromtopperc:pr/QC_SELECTEQI

Jul 12, 2025

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

topperc merged 1 commit intollvm:mainfromtopperc:pr/QC_SELECTEQI

Jul 12, 2025

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topperc commentedJul 11, 2025

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

[RISCV] Use Predicates instead of Added Complexity to prefer QC_SELEC…

a454651

…TEQI over QC_MVEQI. NFCIMHO AddedComplexity should be used as a last resort. We shoulduse other mechanism like Predicates and PatFrag predicates to givepriority.

topperc requested review fromlenary,svs-quic andhchandel

July 11, 2025 22:45

llvmbot added the backend:RISC-V label

Jul 11, 2025

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llvmbot commentedJul 11, 2025

@llvm/pr-subscribers-backend-risc-v

Author: Craig Topper (topperc)

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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.

Full diff:https://github.com/llvm/llvm-project/pull/148312.diff

2 Files Affected:

(modified) llvm/lib/Target/RISCV/RISCVFeatures.td (+2)
(modified) llvm/lib/Target/RISCV/RISCVInstrInfoXqci.td (+6-6)

diff --git a/llvm/lib/Target/RISCV/RISCVFeatures.td b/llvm/lib/Target/RISCV/RISCVFeatures.tdindex 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.tdindex 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>;