[CSKY] Optimize subtraction with SUBI32/SUBI16

Reviewed By: zixuan-wu Differential Revision: https://reviews.llvm.org/D153326
llvm · Jun 30, 2023 · f40682a · f40682a
1 parent 742939f
commit f40682a
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Showing 3 changed files with 148 additions and 52 deletions.
diff --git a/llvm/lib/Target/CSKY/CSKYInstrInfo.td b/llvm/lib/Target/CSKY/CSKYInstrInfo.td
@@ -102,6 +102,14 @@ class oimm<int num> : Operand<i32>,
   let DecoderMethod = "decodeOImmOperand<"#num#">";
 }
 
+def imm_neg_XFORM : SDNodeXForm<imm, [{
+  return CurDAG->getTargetConstant(-N->getSExtValue(), SDLoc(N), MVT::i32);
+}]>;
+
+class oimm_neg<int num> : Operand<i32>,
+  ImmLeaf<i32, "return isUInt<"#num#">(-Imm - 1);"> {
+}
+
 class uimm<int num, int shift = 0> : Operand<i32>,
   ImmLeaf<i32, "return isShiftedUInt<"#num#", "#shift#">(Imm);"> {
   let EncoderMethod = "getImmOpValue<"#shift#">";
@@ -259,6 +267,23 @@ def oimm16 : oimm<16> {
   }];
 }
 
+def oimm8_neg : oimm_neg<8> {
+  let MCOperandPredicate = [{
+    int64_t Imm;
+    if (MCOp.evaluateAsConstantImm(Imm))
+      return isUInt<8>(-Imm - 1);
+    return MCOp.isBareSymbolRef();
+  }];
+}
+def oimm12_neg : oimm_neg<12> {
+  let MCOperandPredicate = [{
+    int64_t Imm;
+    if (MCOp.evaluateAsConstantImm(Imm))
+      return isUInt<12>(-Imm - 1);
+    return MCOp.isBareSymbolRef();
+  }];
+}
+
 def nimm12 : nimm<12>;
 
 def uimm1 : uimm<1>;
@@ -518,6 +543,9 @@ let Predicates = [iHasE2] in {
   let Size = 8 in
   def RSUBI32 : CSKYPseudo<(outs GPR:$rd), (ins GPR:$rx, uimm12:$imm12), "rsubi32 $rd, $rx, $imm12", []>;
 
+  def : Pat<(add GPR:$rs1, (oimm12_neg:$im)),
+            (SUBI32 GPR:$rs1, (imm_neg_XFORM oimm12_neg:$im))>;
+
   def LSL32 : R_YXZ_SP_F1<0x10, 0x1,
     BinOpFrag<(shl node:$LHS, node:$RHS)>, "lsl32">;
   def LSR32 : R_YXZ_SP_F1<0x10, 0x2,

diff --git a/llvm/lib/Target/CSKY/CSKYInstrInfo16Instr.td b/llvm/lib/Target/CSKY/CSKYInstrInfo16Instr.td
@@ -97,6 +97,9 @@ let Constraints = "$rZ = $rz", isReMaterializable = 1, isAsCheapAsAMove = 1 in {
   def SUBI16 : I16_Z_8<0b101, (ins mGPR:$rZ, oimm8:$imm8), "subi16\t$rz, $imm8">;
 }
 
+def : Pat<(add GPR:$rs1, (oimm8_neg:$im)),
+          (SUBI16 GPR:$rs1, (imm_neg_XFORM oimm8_neg:$im))>;
+
 let isAdd = 1 in
 def ADDI16ZSP : I16_Z_8<0b011, (ins GPRSP:$sp, uimm8_2:$imm8),
                         "addi16\t$rz, $sp, $imm8">;