[llvm] [RISCV][GISel] Lower G_SSUBE (PR #157855)
via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 10 18:52:12 PDT 2025
================
@@ -9298,6 +9300,28 @@ LegalizerHelper::lowerSADDO_SSUBO(MachineInstr &MI) {
return Legalized;
}
+LegalizerHelper::LegalizeResult
+LegalizerHelper::lowerSSUBE(MachineInstr &MI) {
+ auto [Res, OvOut, LHS, RHS, CarryIn] = MI.getFirst5Regs();
+ const LLT Ty = MRI.getType(Res);
+
+ // sum = LHS - (RHS + zext(CarryIn))
+ auto CarryZ = MIRBuilder.buildZExt(Ty, CarryIn);
+ auto RHSp = MIRBuilder.buildAdd(Ty, RHS, CarryZ);
+ auto Sum = MIRBuilder.buildSub(Ty, LHS, RHSp);
+ MIRBuilder.buildCopy(Res, Sum);
----------------
woruyu wrote:
OK!
https://github.com/llvm/llvm-project/pull/157855
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