[PATCH] D66950: [SimplifyCFG] Skip sinking common lifetime markers of `alloca`.

[Michael Liao via Phabricator via llvm-commits]

hliao created this revision.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.

- Similar to the workaround in fix of PR30188, skip sinking common lifetime markers of `alloca`. They are mostly left there after inlining functions in branches.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D66950

Files:
  llvm/lib/Transforms/Utils/SimplifyCFG.cpp
  llvm/test/Transforms/SimplifyCFG/sink-common-code.ll


Index: llvm/test/Transforms/SimplifyCFG/sink-common-code.ll
===================================================================
--- llvm/test/Transforms/SimplifyCFG/sink-common-code.ll
+++ llvm/test/Transforms/SimplifyCFG/sink-common-code.ll
@@ -886,6 +886,33 @@
 ; CHECK: ret
 }
 
+; CHECK-LABEL: @test_not_sink_lifetime_marker
+; CHECK-NOT: select
+; CHECK: call void @llvm.lifetime.end
+; CHECK: call void @llvm.lifetime.end
+define i32 @test_not_sink_lifetime_marker(i1 zeroext %flag, i32 %x) {
+entry:
+  %y = alloca i32
+  %z = alloca i32
+  br i1 %flag, label %if.then, label %if.else
+
+if.then:
+  %y.cast = bitcast i32* %y to i8*
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %y.cast)
+  br label %if.end
+
+if.else:
+  %z.cast = bitcast i32* %z to i8*
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %z.cast)
+  br label %if.end
+
+if.end:
+  ret i32 1
+}
+
+declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
+declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture)
+
 
 ; CHECK: ![[$TBAA]] = !{![[TYPE:[0-9]]], ![[TYPE]], i64 0}
 ; CHECK: ![[TYPE]] = !{!"float", ![[TEXT:[0-9]]]}
Index: llvm/lib/Transforms/Utils/SimplifyCFG.cpp
===================================================================
--- llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1484,11 +1484,29 @@
   // FIXME: This is a workaround for a deficiency in SROA - see
   // https://llvm.org/bugs/show_bug.cgi?id=30188
   if (isa<StoreInst>(I0) && any_of(Insts, [](const Instruction *I) {
-        return isa<AllocaInst>(I->getOperand(1));
+        return isa<AllocaInst>(I->getOperand(1)->stripPointerCasts());
       }))
     return false;
   if (isa<LoadInst>(I0) && any_of(Insts, [](const Instruction *I) {
-        return isa<AllocaInst>(I->getOperand(0));
+        return isa<AllocaInst>(I->getOperand(0)->stripPointerCasts());
+      }))
+    return false;
+
+  auto isLifeTimeMarker = [](const Instruction *I) {
+    if (auto II = dyn_cast<IntrinsicInst>(I)) {
+      switch (II->getIntrinsicID()) {
+      default:
+        break;
+      case Intrinsic::lifetime_start:
+      case Intrinsic::lifetime_end:
+        return true;
+      }
+    }
+    return false;
+  };
+
+  if (isLifeTimeMarker(I0) && any_of(Insts, [](const Instruction *I) {
+        return isa<AllocaInst>(I->getOperand(1)->stripPointerCasts());
       }))
     return false;
 


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