[llvm] ad95255 - Revert "[LICM] Only create load in pre-header when promoting load."

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2022-04-13T20:24:28+02:00
New Revision: ad95255b9215a9e467169e6109bd53561e589f0b

URL: https://github.com/llvm/llvm-project/commit/ad95255b9215a9e467169e6109bd53561e589f0b
DIFF: https://github.com/llvm/llvm-project/commit/ad95255b9215a9e467169e6109bd53561e589f0b.diff

LOG: Revert "[LICM] Only create load in pre-header when promoting load."

This reverts commit 4bf3b7dc929c8288e9e5631978ef060d9140b251.

This might be causing another buildbot failure.

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/LICM.cpp
    llvm/test/Transforms/LICM/scalar-promote.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index a7e47fe797133..74ae5977a3663 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -2156,26 +2156,21 @@ bool llvm::promoteLoopAccessesToScalars(
 
   // Set up the preheader to have a definition of the value.  It is the live-out
   // value from the preheader that uses in the loop will use.
-  LoadInst *PreheaderLoad = nullptr;
-  if (FoundLoadToPromote) {
-    PreheaderLoad =
-        new LoadInst(AccessTy, SomePtr, SomePtr->getName() + ".promoted",
-                     Preheader->getTerminator());
-    if (SawUnorderedAtomic)
-      PreheaderLoad->setOrdering(AtomicOrdering::Unordered);
-    PreheaderLoad->setAlignment(Alignment);
-    PreheaderLoad->setDebugLoc(DebugLoc());
-    if (AATags)
-      PreheaderLoad->setAAMetadata(AATags);
-
-    MemoryAccess *PreheaderLoadMemoryAccess = MSSAU.createMemoryAccessInBB(
-        PreheaderLoad, nullptr, PreheaderLoad->getParent(), MemorySSA::End);
-    MemoryUse *NewMemUse = cast<MemoryUse>(PreheaderLoadMemoryAccess);
-    MSSAU.insertUse(NewMemUse, /*RenameUses=*/true);
-    SSA.AddAvailableValue(Preheader, PreheaderLoad);
-  } else {
-    SSA.AddAvailableValue(Preheader, PoisonValue::get(AccessTy));
-  }
+  LoadInst *PreheaderLoad = new LoadInst(
+      AccessTy, SomePtr, SomePtr->getName() + ".promoted",
+      Preheader->getTerminator());
+  if (SawUnorderedAtomic)
+    PreheaderLoad->setOrdering(AtomicOrdering::Unordered);
+  PreheaderLoad->setAlignment(Alignment);
+  PreheaderLoad->setDebugLoc(DebugLoc());
+  if (AATags)
+    PreheaderLoad->setAAMetadata(AATags);
+  SSA.AddAvailableValue(Preheader, PreheaderLoad);
+
+  MemoryAccess *PreheaderLoadMemoryAccess = MSSAU.createMemoryAccessInBB(
+      PreheaderLoad, nullptr, PreheaderLoad->getParent(), MemorySSA::End);
+  MemoryUse *NewMemUse = cast<MemoryUse>(PreheaderLoadMemoryAccess);
+  MSSAU.insertUse(NewMemUse, /*RenameUses=*/true);
 
   if (VerifyMemorySSA)
     MSSAU.getMemorySSA()->verifyMemorySSA();
@@ -2186,7 +2181,7 @@ bool llvm::promoteLoopAccessesToScalars(
   if (VerifyMemorySSA)
     MSSAU.getMemorySSA()->verifyMemorySSA();
   // If the SSAUpdater didn't use the load in the preheader, just zap it now.
-  if (PreheaderLoad && PreheaderLoad->use_empty())
+  if (PreheaderLoad->use_empty())
     eraseInstruction(*PreheaderLoad, *SafetyInfo, MSSAU);
 
   return true;

diff  --git a/llvm/test/Transforms/LICM/scalar-promote.ll b/llvm/test/Transforms/LICM/scalar-promote.ll
index 12f1164cd7d27..ad60bc87b910a 100644
--- a/llvm/test/Transforms/LICM/scalar-promote.ll
+++ b/llvm/test/Transforms/LICM/scalar-promote.ll
@@ -605,9 +605,10 @@ Out:
 define void @test_sink_store_only() writeonly {
 ; CHECK-LABEL: @test_sink_store_only(
 ; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[GLB_PROMOTED:%.*]] = load i8, i8* @glb, align 1
 ; CHECK-NEXT:    br label [[LOOP_HEADER:%.*]]
 ; CHECK:       loop.header:
-; CHECK-NEXT:    [[DIV1:%.*]] = phi i8 [ poison, [[ENTRY:%.*]] ], [ [[DIV:%.*]], [[LOOP_LATCH:%.*]] ]
+; CHECK-NEXT:    [[DIV1:%.*]] = phi i8 [ [[GLB_PROMOTED]], [[ENTRY:%.*]] ], [ [[DIV:%.*]], [[LOOP_LATCH:%.*]] ]
 ; CHECK-NEXT:    [[I:%.*]] = phi i8 [ 0, [[ENTRY]] ], [ [[ADD:%.*]], [[LOOP_LATCH]] ]
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i8 [[I]], 4
 ; CHECK-NEXT:    br i1 [[CMP]], label [[LOOP_LATCH]], label [[EXIT:%.*]]
@@ -668,58 +669,6 @@ exit:
   ret void
 }
 
-define void @sink_store_lcssa_phis(i32* %ptr, i1 %c) {
-; CHECK-LABEL: @sink_store_lcssa_phis(
-; CHECK-NEXT:  entry:
-; CHECK-NEXT:    br label [[LOOP_1_HEADER:%.*]]
-; CHECK:       loop.1.header:
-; CHECK-NEXT:    br label [[LOOP_2_HEADER:%.*]]
-; CHECK:       loop.2.header:
-; CHECK-NEXT:    br i1 false, label [[LOOP_3_HEADER_PREHEADER:%.*]], label [[LOOP_1_LATCH:%.*]]
-; CHECK:       loop.3.header.preheader:
-; CHECK-NEXT:    br label [[LOOP_3_HEADER:%.*]]
-; CHECK:       loop.3.header:
-; CHECK-NEXT:    [[I_11:%.*]] = phi i32 [ [[I_1:%.*]], [[LOOP_3_LATCH:%.*]] ], [ poison, [[LOOP_3_HEADER_PREHEADER]] ]
-; CHECK-NEXT:    [[I_1]] = phi i32 [ 1, [[LOOP_3_LATCH]] ], [ 0, [[LOOP_3_HEADER_PREHEADER]] ]
-; CHECK-NEXT:    br i1 true, label [[LOOP_3_LATCH]], label [[LOOP_2_LATCH:%.*]]
-; CHECK:       loop.3.latch:
-; CHECK-NEXT:    br label [[LOOP_3_HEADER]]
-; CHECK:       loop.2.latch:
-; CHECK-NEXT:    [[I_11_LCSSA:%.*]] = phi i32 [ [[I_11]], [[LOOP_3_HEADER]] ]
-; CHECK-NEXT:    store i32 [[I_11_LCSSA]], i32* [[PTR:%.*]], align 4
-; CHECK-NEXT:    br label [[LOOP_2_HEADER]]
-; CHECK:       loop.1.latch:
-; CHECK-NEXT:    br i1 [[C:%.*]], label [[LOOP_1_HEADER]], label [[EXIT:%.*]]
-; CHECK:       exit:
-; CHECK-NEXT:    ret void
-;
-entry:
-  br label %loop.1.header
-
-loop.1.header:
-  br label %loop.2.header
-
-loop.2.header:
-  br i1 false, label %loop.3.header, label %loop.1.latch
-
-loop.3.header:
-  %i.1 = phi i32 [ 1, %loop.3.latch ], [ 0, %loop.2.header ]
-  br i1 true, label %loop.3.latch, label %loop.2.latch
-
-loop.3.latch:
-  store i32 %i.1, i32* %ptr, align 4
-  br label %loop.3.header
-
-loop.2.latch:
-  br label %loop.2.header
-
-loop.1.latch:
-  br i1 %c, label %loop.1.header, label %exit
-
-exit:
-  ret void
-}
-
 !0 = !{!4, !4, i64 0}
 !1 = !{!"omnipotent char", !2}
 !2 = !{!"Simple C/C++ TBAA"}