[PATCH] D95169: [RISCV] Add more cmov isel patterns to handle seteq/ne with a small non-zero immediate.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: asb, mundaym, luismarques.
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Similar to our free standing setcc patterns, we can use ADDI to
subtract the immediate from the other operand. Then the cmov
can check if the result is zero or non-zero.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D95169

Files:
  llvm/lib/Target/RISCV/RISCVInstrInfoB.td
  llvm/test/CodeGen/RISCV/select-optimize-multiple.ll


Index: llvm/test/CodeGen/RISCV/select-optimize-multiple.ll
===================================================================
--- llvm/test/CodeGen/RISCV/select-optimize-multiple.ll
+++ llvm/test/CodeGen/RISCV/select-optimize-multiple.ll
@@ -27,8 +27,7 @@
 ;
 ; RV32IBT-LABEL: cmovcc64:
 ; RV32IBT:       # %bb.0: # %entry
-; RV32IBT-NEXT:    addi a5, zero, 123
-; RV32IBT-NEXT:    xor a5, a0, a5
+; RV32IBT-NEXT:    addi a5, a0, -123
 ; RV32IBT-NEXT:    cmov a0, a5, a3, a1
 ; RV32IBT-NEXT:    cmov a1, a5, a4, a2
 ; RV32IBT-NEXT:    ret
@@ -45,8 +44,7 @@
 ;
 ; RV64IBT-LABEL: cmovcc64:
 ; RV64IBT:       # %bb.0: # %entry
-; RV64IBT-NEXT:    addi a3, zero, 123
-; RV64IBT-NEXT:    xor a0, a0, a3
+; RV64IBT-NEXT:    addi a0, a0, -123
 ; RV64IBT-NEXT:    cmov a0, a0, a2, a1
 ; RV64IBT-NEXT:    ret
 entry:
@@ -133,8 +131,7 @@
 ;
 ; RV64IBT-LABEL: cmovcc128:
 ; RV64IBT:       # %bb.0: # %entry
-; RV64IBT-NEXT:    addi a5, zero, 123
-; RV64IBT-NEXT:    xor a5, a0, a5
+; RV64IBT-NEXT:    addi a5, a0, -123
 ; RV64IBT-NEXT:    cmov a0, a5, a3, a1
 ; RV64IBT-NEXT:    cmov a1, a5, a4, a2
 ; RV64IBT-NEXT:    ret
@@ -434,8 +431,7 @@
 ;
 ; RV32IBT-LABEL: cmovccdep:
 ; RV32IBT:       # %bb.0: # %entry
-; RV32IBT-NEXT:    addi a4, zero, 123
-; RV32IBT-NEXT:    xor a0, a0, a4
+; RV32IBT-NEXT:    addi a0, a0, -123
 ; RV32IBT-NEXT:    cmov a1, a0, a2, a1
 ; RV32IBT-NEXT:    cmov a0, a0, a3, a1
 ; RV32IBT-NEXT:    add a0, a1, a0
@@ -462,8 +458,7 @@
 ;
 ; RV64IBT-LABEL: cmovccdep:
 ; RV64IBT:       # %bb.0: # %entry
-; RV64IBT-NEXT:    addi a4, zero, 123
-; RV64IBT-NEXT:    xor a0, a0, a4
+; RV64IBT-NEXT:    addi a0, a0, -123
 ; RV64IBT-NEXT:    cmov a1, a0, a2, a1
 ; RV64IBT-NEXT:    cmov a0, a0, a3, a1
 ; RV64IBT-NEXT:    addw a0, a1, a0
Index: llvm/lib/Target/RISCV/RISCVInstrInfoB.td
===================================================================
--- llvm/lib/Target/RISCV/RISCVInstrInfoB.td
+++ llvm/lib/Target/RISCV/RISCVInstrInfoB.td
@@ -717,10 +717,15 @@
 let Predicates = [HasStdExtZbt] in {
 def : Pat<(or (and (not GPR:$rs2), GPR:$rs3), (and GPR:$rs2, GPR:$rs1)),
           (CMIX GPR:$rs1, GPR:$rs2, GPR:$rs3)>;
+
 def : Pat<(select (XLenVT (setne GPR:$rs2, 0)), GPR:$rs1, GPR:$rs3),
           (CMOV GPR:$rs1, GPR:$rs2, GPR:$rs3)>;
 def : Pat<(select (XLenVT (seteq GPR:$rs2, 0)), GPR:$rs3, GPR:$rs1),
           (CMOV GPR:$rs1, GPR:$rs2, GPR:$rs3)>;
+def : Pat<(select (XLenVT (setne GPR:$x, simm12_plus1:$y)), GPR:$rs1, GPR:$rs3),
+          (CMOV GPR:$rs1, (ADDI GPR:$x, (NegImm simm12_plus1:$y)), GPR:$rs3)>;
+def : Pat<(select (XLenVT (seteq GPR:$x, simm12_plus1:$y)), GPR:$rs3, GPR:$rs1),
+          (CMOV GPR:$rs1, (ADDI GPR:$x, (NegImm simm12_plus1:$y)), GPR:$rs3)>;
 def : Pat<(select (XLenVT (setne GPR:$x, GPR:$y)), GPR:$rs1, GPR:$rs3),
           (CMOV GPR:$rs1, (XOR GPR:$x, GPR:$y), GPR:$rs3)>;
 def : Pat<(select (XLenVT (seteq GPR:$x, GPR:$y)), GPR:$rs3, GPR:$rs1),


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