[PATCH] D47011: SafepointIRVerifier is made unreachable block tolerant

[Yevgeny Rouban via Phabricator via llvm-commits]

yrouban created this revision.
yrouban added reviewers: anna, reames, dneilson, DaniilSuchkov, skatkov.

SafepointIRVerifier crashed while traversing blocks without a DomTreeNode.
This could happen with a custom pipeline or when some optional passes were skipped by OptBisect.

SafepointIRVerifier is fixed to traverse basic blocks that are reachable
from entry. One simple test is added.


https://reviews.llvm.org/D47011

Files:
  lib/IR/SafepointIRVerifier.cpp
  test/SafepointIRVerifier/unreachable-block-tolerant.ll


Index: test/SafepointIRVerifier/unreachable-block-tolerant.ll
===================================================================
--- test/SafepointIRVerifier/unreachable-block-tolerant.ll
+++ test/SafepointIRVerifier/unreachable-block-tolerant.ll
@@ -0,0 +1,23 @@
+; RUN: opt -safepoint-ir-verifier-print-only -verify-safepoint-ir -S %s 2>&1 | FileCheck %s
+
+; This test checks that StatepointIRVerifier does not crash on
+; a CFG with unreachable blocks.
+
+%jObject = type { [8 x i8] }
+
+; Function Attrs: nounwind
+define %jObject addrspace(1)* @test(%jObject addrspace(1)* %arg) gc "statepoint-example" {
+; CHECK:      Verifying gc pointers in function: test
+; CHECK-NEXT: No illegal uses found by SafepointIRVerifier in: test
+  %safepoint_token3 = tail call token (i64, i32, double (double)*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_f64f64f(i64 0, i32 0, double (double)* undef, i32 1, i32 0, double undef, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0, %jObject addrspace(1)* %arg)
+  %arg2.relocated4 = call coldcc %jObject addrspace(1)* @llvm.experimental.gc.relocate.p1jObject(token %safepoint_token3, i32 13, i32 13)
+  ret %jObject addrspace(1)* %arg2.relocated4
+
+unreachable:
+  ret %jObject addrspace(1)* null
+}
+
+; Function Attrs: nounwind
+declare %jObject addrspace(1)* @llvm.experimental.gc.relocate.p1jObject(token, i32, i32) #3
+
+declare token @llvm.experimental.gc.statepoint.p0f_f64f64f(i64, i32, double (double)*, i32, i32, ...)
Index: lib/IR/SafepointIRVerifier.cpp
===================================================================
--- lib/IR/SafepointIRVerifier.cpp
+++ lib/IR/SafepointIRVerifier.cpp
@@ -374,12 +374,13 @@
 
 GCPtrTracker::GCPtrTracker(const Function &F, const DominatorTree &DT) : F(F) {
   // First, calculate Contribution of each BB.
-  for (const BasicBlock &BB : F) {
-    BasicBlockState *BBS = new (BSAllocator.Allocate()) BasicBlockState;
-    for (const auto &I : BB)
-      transferInstruction(I, BBS->Cleared, BBS->Contribution);
-    BlockMap[&BB] = BBS;
-  }
+  for (const BasicBlock &BB : F)
+    if (DT.isReachableFromEntry(&BB)) {
+      BasicBlockState *BBS = new (BSAllocator.Allocate()) BasicBlockState;
+      for (const auto &I : BB)
+        transferInstruction(I, BBS->Cleared, BBS->Contribution);
+      BlockMap[&BB] = BBS;
+    }
 
   // Initialize AvailableIn/Out sets of each BB using only information about
   // dominating BBs.
@@ -560,6 +561,7 @@
                                         const DominatorTree &DT) {
   DomTreeNode *DTN = DT[const_cast<BasicBlock *>(BB)];
 
+  assert(DTN && "Unreachable blocks are ignored");
   while (DTN->getIDom()) {
     DTN = DTN->getIDom();
     const auto &Defs = BlockMap[DTN->getBlock()]->Contribution;


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