[PATCH] D84785: [PowerPC] Don't remove swap if there is only a single one between the load and store

[Nemanja Ivanovic via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG14d726acd604: [PowerPC] Don't remove single swap between the load and store (authored by nemanjai).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D84785/new/

https://reviews.llvm.org/D84785

Files:
  llvm/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp
  llvm/test/CodeGen/PowerPC/swaps-le-8.ll


Index: llvm/test/CodeGen/PowerPC/swaps-le-8.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/PowerPC/swaps-le-8.ll
@@ -0,0 +1,19 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -verify-machineinstrs -O3 -mcpu=pwr8 \
+; RUN:   -mtriple=powerpc64le-unknown-linux-gnu < %s | FileCheck %s
+define dso_local void @test(i64* %Src, i64* nocapture %Tgt) local_unnamed_addr {
+; CHECK-LABEL: test:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    lxvd2x 0, 0, 3
+; CHECK-NEXT:    xxswapd 0, 0
+; CHECK-NEXT:    stxvd2x 0, 0, 4
+; CHECK-NEXT:    blr
+entry:
+  %0 = bitcast i64* %Src to i8*
+  %1 = tail call <2 x double> @llvm.ppc.vsx.lxvd2x.be(i8* %0) #2
+  %2 = bitcast i64* %Tgt to <2 x double>*
+  store <2 x double> %1, <2 x double>* %2, align 1
+  ret void
+}
+
+declare <2 x double> @llvm.ppc.vsx.lxvd2x.be(i8*) #1
Index: llvm/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp
===================================================================
--- llvm/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp
+++ llvm/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp
@@ -689,6 +689,29 @@
           LLVM_DEBUG(UseMI.dump());
           LLVM_DEBUG(dbgs() << "\n");
         }
+
+        // It is possible that the load feeds a swap and that swap feeds a
+        // store. In such a case, the code is actually trying to store a swapped
+        // vector. We must reject such webs.
+        if (SwapVector[UseIdx].IsSwap && !SwapVector[UseIdx].IsLoad &&
+            !SwapVector[UseIdx].IsStore) {
+          Register SwapDefReg = UseMI.getOperand(0).getReg();
+          for (MachineInstr &UseOfUseMI :
+               MRI->use_nodbg_instructions(SwapDefReg)) {
+            int UseOfUseIdx = SwapMap[&UseOfUseMI];
+            if (SwapVector[UseOfUseIdx].IsStore) {
+              SwapVector[Repr].WebRejected = 1;
+              LLVM_DEBUG(
+                  dbgs() << format(
+                      "Web %d rejected for load/swap feeding a store\n", Repr));
+              LLVM_DEBUG(dbgs() << "  def " << EntryIdx << ": ");
+              LLVM_DEBUG(MI->dump());
+              LLVM_DEBUG(dbgs() << "  use " << UseIdx << ": ");
+              LLVM_DEBUG(UseMI.dump());
+              LLVM_DEBUG(dbgs() << "\n");
+            }
+          }
+        }
       }
 
     // Reject webs that contain swapping stores that are fed by something


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