[PATCH] D55027: [CallSiteSplitting] Report edge deletion to DomTreeUpdater

[Joseph Tremoulet via Phabricator via llvm-commits]

JosephTremoulet created this revision.
JosephTremoulet added reviewers: fhahn, junbuml.
Herald added a subscriber: llvm-commits.

When splitting musttail calls, the split blocks' original terminators
get removed; inform the DTU when this happens.

Also add a testcase that fails an assertion in the DTU without this fix.


Repository:
  rL LLVM

https://reviews.llvm.org/D55027

Files:
  lib/Transforms/Scalar/CallSiteSplitting.cpp
  test/Transforms/CallSiteSplitting/musttail.ll


Index: test/Transforms/CallSiteSplitting/musttail.ll
===================================================================
--- test/Transforms/CallSiteSplitting/musttail.ll
+++ test/Transforms/CallSiteSplitting/musttail.ll
@@ -73,3 +73,32 @@
 define void @void_callee(i8* %a, i8* %b) noinline {
   ret void
 }
+
+;   Include a test with a larger CFG that exercises the DomTreeUpdater
+;   machinery a bit more.
+;CHECK-LABEL: @larger_cfg_caller
+;CHECK-LABEL: Top.split:
+;CHECK: %r1 = musttail call i8* @callee(i8* null, i8* %b)
+;CHECK: ret i8* %r1
+;CHECK-LABEL: TBB.split
+;CHECK: %r2 = musttail call i8* @callee(i8* nonnull %a, i8* null)
+;CHECK: ret i8* %r2
+define i8* @larger_cfg_caller(i8* %a, i8* %b) {
+Top:
+  %cond1 = icmp eq i8* %a, null
+  br i1 %cond1, label %Tail, label %ExtraTest
+ExtraTest:
+  %a0 = load i8, i8* %a
+  %cond2 = icmp eq i8 %a0, 0
+  br i1 %cond2, label %TBB_pred, label %End
+TBB_pred:
+  br label %TBB
+TBB:
+  %cond3 = icmp eq i8* %b, null
+  br i1 %cond3, label %Tail, label %End
+Tail:
+  %r = musttail call i8* @callee(i8* %a, i8* %b)
+  ret i8* %r
+End:
+  ret i8* null
+}
Index: lib/Transforms/Scalar/CallSiteSplitting.cpp
===================================================================
--- lib/Transforms/Scalar/CallSiteSplitting.cpp
+++ lib/Transforms/Scalar/CallSiteSplitting.cpp
@@ -365,8 +365,10 @@
     // attempting removal.
     SmallVector<BasicBlock *, 2> Splits(predecessors((TailBB)));
     assert(Splits.size() == 2 && "Expected exactly 2 splits!");
-    for (unsigned i = 0; i < Splits.size(); i++)
+    for (unsigned i = 0; i < Splits.size(); i++) {
       Splits[i]->getTerminator()->eraseFromParent();
+      DTU.deleteEdge(Splits[i], TailBB);
+    }
 
     // Erase the tail block once done with musttail patching
     DTU.deleteBB(TailBB);


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