[PATCH] D99058: [RS4GC] Fix hang on infinite loop

[Serguei Katkov via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG9fec382601df: [RS4GC] Fix hang on infinite loop (authored by skatkov).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D99058/new/

https://reviews.llvm.org/D99058

Files:
  llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
  llvm/test/Transforms/RewriteStatepointsForGC/meetBDVState-hangs.ll


Index: llvm/test/Transforms/RewriteStatepointsForGC/meetBDVState-hangs.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/RewriteStatepointsForGC/meetBDVState-hangs.ll
@@ -0,0 +1,63 @@
+; RUN: opt -S -rewrite-statepoints-for-gc < %s | FileCheck %s
+
+; Regression test to incorrectly testing fixed state causing infinite loop.
+; CHECK: test
+target triple = "x86_64-unknown-linux-gnu"
+
+declare void @bar(i8 addrspace(1)* nocapture readonly)
+declare noalias i8 addrspace(1)* @foo()
+
+define i8 addrspace(1)* @test(i1 %c, i1 %c1, i1 %c2, i1 %c3, i1 %c4, i1 %c5, i1 %c.exit) gc "statepoint-example" {
+entry:
+  br i1 %c, label %ph.L, label %ph.R
+ph.L:
+  %ph.L.p.b = call noalias nonnull i8 addrspace(1)* @foo()
+  %ph.L.p = getelementptr i8, i8 addrspace(1)* %ph.L.p.b, i64 8
+  br label %ph.M
+ph.R:
+  %ph.R.p = call noalias nonnull i8 addrspace(1)* @foo()
+  br label %ph.M
+ph.M:
+  %ph.M.p = phi i8 addrspace(1)* [ %ph.L.p, %ph.L ], [ %ph.R.p, %ph.R ]
+  br label %header
+  
+header:
+  %header.p = phi i8 addrspace(1)* [ %ph.M.p, %ph.M ], [ %backedge.p, %backedge]
+  br i1 %c1, label %loop.M, label %loop.R
+
+loop.R:
+  br i1 %c2, label %loop.R.M, label %loop.R.R
+
+loop.R.R:
+  %loop.R.R.p = call noalias nonnull i8 addrspace(1)* @foo()
+  br label %loop.R.M
+
+loop.R.M:
+  %loop.R.M.p = phi i8 addrspace(1)* [ %header.p, %loop.R ], [ %loop.R.R.p, %loop.R.R ]
+  br label %loop.M
+
+loop.M:
+  %loop.M.p = phi i8 addrspace(1)* [ %loop.R.M.p, %loop.R.M ], [ %header.p, %header ]
+  br i1 %c4, label %backedge, label %pre.backedge.R
+  
+pre.backedge.R:
+  br i1 %c5, label %pre.backedge.R.L, label %pre.backedge.R.R
+pre.backedge.R.L:
+  %pre.backedge.R.L.p.b = call noalias nonnull i8 addrspace(1)* @foo()
+  %pre.backedge.R.L.p = getelementptr i8, i8 addrspace(1)* %pre.backedge.R.L.p.b, i64 8
+  br label %pre.backedge.R.M
+pre.backedge.R.R:
+  %pre.backedge.R.R.p = call noalias nonnull i8 addrspace(1)* @foo()
+  br label %pre.backedge.R.M
+pre.backedge.R.M:
+  %pre.backedge.R.M.p = phi i8 addrspace(1)* [ %pre.backedge.R.L.p, %pre.backedge.R.L ], [ %pre.backedge.R.R.p, %pre.backedge.R.R ]
+  br label %backedge
+  
+backedge:
+  %backedge.p = phi i8 addrspace(1)* [ %pre.backedge.R.M.p, %pre.backedge.R.M ], [ %loop.M.p, %loop.M ]
+  br i1 %c.exit, label %header, label %exit
+  
+exit:                                                ; preds = %3, %1
+  call void @bar(i8 addrspace(1)* align 8 %header.p) [ "deopt"() ]
+  ret i8 addrspace(1)* %header.p
+}
Index: llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -782,8 +782,9 @@
   if (LHS.getStatus() == BDVState::Base && RHS.getStatus() == BDVState::Base &&
       LHS.getBaseValue() != RHS.getBaseValue()) {
     NewStatus = BDVState::Conflict;
-    BaseValue = nullptr;
   }
+  if (NewStatus == BDVState::Conflict)
+    BaseValue = nullptr;
   return BDVState(LHS.getOriginalValue(), NewStatus, BaseValue);
 }
 


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