[llvm] [GISel] Convert zext nneg to sext if it is cheaper (PR #93856)

[Yingwei Zheng via llvm-commits]

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@@ -101,3 +101,13 @@ entry:
   %0 = urem i64 %a, %b
   ret i64 %0
 }
+
+define i64 @zext_nneg_i32_i64(i32 %a) {
+; RV64IM-LABEL: zext_nneg_i32_i64:
+; RV64IM:       # %bb.0: # %entry
+; RV64IM-NEXT:    sext.w a0, a0
+; RV64IM-NEXT:    ret
+entry:
+  %b = zext nneg i32 %a to i64
+  ret i64 %b
+}
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dtcxzyw wrote:

Sorry, I cannot provide vector tests as both RISC-V and LoongArch only handle scalar i32 -> i64.
https://github.com/llvm/llvm-project/blob/a65771fce4a2f25f16d4b3918ad6a11370637f7b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp#L1881-L1883
https://github.com/llvm/llvm-project/blob/a65771fce4a2f25f16d4b3918ad6a11370637f7b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp#L4982-L4985

https://github.com/llvm/llvm-project/pull/93856