[SVE] Fix bug in SVEIntrinsicOpts::optimizePTest

[david-arm]

Summary

The code wasn't taking into account that the two operands
passed to ptest could be identical and was trying to erase
them twice.

[efriedma]

LGTM

llvm/test/CodeGen/AArch64/sve-intrinsic-opts-ptest.ll

51

Might want to consider regenerating this test file using update_test_checks.py; easier than trying to write precise CHECK lines by hand. But doesn't need to be this patch.

llvm/lib/Target/AArch64/SVEIntrinsicOpts.cpp

if (Op1 && Op2 &&
 
     auto Fn = Intrinsic::getDeclaration(M, I->getIntrinsicID(), Tys);
     auto CI = CallInst::Create(Fn, Ops, I->getName(), I);
 
     I->replaceAllUsesWith(CI);
     I->eraseFromParent();
     if (Op1->use_empty())
       Op1->eraseFromParent();
-    if (Op2->use_empty())
+    if (Op1 != Op2 && Op2->use_empty())
       Op2->eraseFromParent();
 
     return true;
   }
 
   return false;
 }
 

llvm/test/CodeGen/AArch64/sve-intrinsic-opts-ptest.ll

 ; OPT-NEXT: ret i1 %[[OUT]]
   %mask = tail call <vscale x 4 x i1> @llvm.aarch64.sve.ptrue.nxv4i1(i32 0)
   %1 = tail call <vscale x 16 x i1> @llvm.aarch64.sve.convert.to.svbool.nxv4i1(<vscale x 4 x i1> %mask)
   %2 = tail call <vscale x 16 x i1> @llvm.aarch64.sve.convert.to.svbool.nxv4i1(<vscale x 4 x i1> %a)
   %out = call i1 @llvm.aarch64.sve.ptest.first.nxv16i1(<vscale x 16 x i1> %1, <vscale x 16 x i1> %2)
   ret i1 %out
 }
 
+define i1 @ptest_first_same_ops(<vscale x 2 x i1> %a) {
+; OPT-LABEL: ptest_first_same_ops
+; OPT: %[[OUT:.*]] = call i1 @llvm.aarch64.sve.ptest.first.nxv2i1(<vscale x 2 x i1> %a, <vscale x 2 x i1> %a)
+; OPT-NOT: convert
+; OPT-NEXT: ret i1 %[[OUT]]
+  %1 = tail call <vscale x 16 x i1> @llvm.aarch64.sve.convert.to.svbool.nxv2i1(<vscale x 2 x i1> %a)
+  %2 = tail call i1 @llvm.aarch64.sve.ptest.first.nxv16i1(<vscale x 16 x i1> %1, <vscale x 16 x i1> %1)
+  ret i1 %2
+}
+
 define i1 @ptest_last(<vscale x 8 x i1> %a) {
 ; OPT-LABEL: ptest_last
 ; OPT: %mask = tail call <vscale x 8 x i1> @llvm.aarch64.sve.ptrue.nxv8i1(i32 0)
 ; OPT-NOT: convert
 ; OPT-NEXT: %[[OUT:.*]] = call i1 @llvm.aarch64.sve.ptest.last.nxv8i1(<vscale x 8 x i1> %mask, <vscale x 8 x i1> %a)
 ; OPT-NEXT: ret i1 %[[OUT]]
   %mask = tail call <vscale x 8 x i1> @llvm.aarch64.sve.ptrue.nxv8i1(i32 0)
   %1 = tail call <vscale x 16 x i1> @llvm.aarch64.sve.convert.to.svbool.nxv8i1(<vscale x 8 x i1> %mask)