[PATCH] D132358: [RISCV][ISel] improved compressed instruction use

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Helping to emit compressed BNEZ in comparasion with constant when possible.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D132358

Files:
  llvm/lib/Target/RISCV/RISCVInstrInfo.td
  llvm/test/CodeGen/RISCV/codemodel-lowering.ll
  llvm/test/CodeGen/RISCV/isel-compressed-comp.ll


Index: llvm/test/CodeGen/RISCV/isel-compressed-comp.ll
===================================================================
--- llvm/test/CodeGen/RISCV/isel-compressed-comp.ll
+++ llvm/test/CodeGen/RISCV/isel-compressed-comp.ll
@@ -1,13 +1,11 @@
-; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s \
-; RUN:   | FileCheck  %s
 ; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck  %s
 
 declare void @foo()
 
 define void @bar(i64 %a) {
-; CHECK-NOT: slti
-; CHECK-NOT: bnez
+; CHECK: slti
+; CHECK-NEXT: bnez
   %c = icmp slt i64  255, %a
   br i1 %c, label %taken, label %return
 taken:
Index: llvm/test/CodeGen/RISCV/codemodel-lowering.ll
===================================================================
--- llvm/test/CodeGen/RISCV/codemodel-lowering.ll
+++ llvm/test/CodeGen/RISCV/codemodel-lowering.ll
@@ -58,9 +58,9 @@
 ; RV32I-SMALL-NEXT:    addi sp, sp, -16
 ; RV32I-SMALL-NEXT:    lui a1, %hi(.Ltmp0)
 ; RV32I-SMALL-NEXT:    addi a1, a1, %lo(.Ltmp0)
-; RV32I-SMALL-NEXT:    li a2, 101
+; RV32I-SMALL-NEXT:    slti a0, a0, 101
 ; RV32I-SMALL-NEXT:    sw a1, 8(sp)
-; RV32I-SMALL-NEXT:    blt a0, a2, .LBB2_3
+; RV32I-SMALL-NEXT:    bnez a0, .LBB2_3
 ; RV32I-SMALL-NEXT:  # %bb.1: # %if.then
 ; RV32I-SMALL-NEXT:    lw a0, 8(sp)
 ; RV32I-SMALL-NEXT:    jr a0
@@ -80,9 +80,9 @@
 ; RV32I-MEDIUM-NEXT:  .Lpcrel_hi2:
 ; RV32I-MEDIUM-NEXT:    auipc a1, %pcrel_hi(.Ltmp0)
 ; RV32I-MEDIUM-NEXT:    addi a1, a1, %pcrel_lo(.Lpcrel_hi2)
-; RV32I-MEDIUM-NEXT:    li a2, 101
+; RV32I-MEDIUM-NEXT:    slti a0, a0, 101
 ; RV32I-MEDIUM-NEXT:    sw a1, 8(sp)
-; RV32I-MEDIUM-NEXT:    blt a0, a2, .LBB2_3
+; RV32I-MEDIUM-NEXT:    bnez a0, .LBB2_3
 ; RV32I-MEDIUM-NEXT:  # %bb.1: # %if.then
 ; RV32I-MEDIUM-NEXT:    lw a0, 8(sp)
 ; RV32I-MEDIUM-NEXT:    jr a0
Index: llvm/lib/Target/RISCV/RISCVInstrInfo.td
===================================================================
--- llvm/lib/Target/RISCV/RISCVInstrInfo.td
+++ llvm/lib/Target/RISCV/RISCVInstrInfo.td
@@ -1329,6 +1329,10 @@
 defm : BccPat<SETULT, BLTU>;
 defm : BccPat<SETUGE, BGEU>;
 
+// Try to produce compressed bnez instruction if possible
+def : Pat<(riscv_brcc GPR:$rs1, simm12:$c, SETLT, bb:$imm12),
+            (BNE (SLTI GPR:$rs1, simm12:$c), X0, simm13_lsb0:$imm12)>;
+
 let isBarrier = 1, isBranch = 1, isTerminator = 1 in
 def PseudoBR : Pseudo<(outs), (ins simm21_lsb0_jal:$imm20), [(br bb:$imm20)]>,
                PseudoInstExpansion<(JAL X0, simm21_lsb0_jal:$imm20)>;


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