[PATCH] D134439: [StructurizeCFG] Remove imposible case, associated test, and replace by assert

[Juan Manuel Martinez Caamaño via Phabricator via llvm-commits]

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Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D134439

Files:
  llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
  llvm/test/Transforms/StructurizeCFG/no-branch-to-entry.ll


Index: llvm/test/Transforms/StructurizeCFG/no-branch-to-entry.ll
===================================================================
--- llvm/test/Transforms/StructurizeCFG/no-branch-to-entry.ll
+++ /dev/null
@@ -1,38 +0,0 @@
-; XFAIL: *
-
-; This test used to generate a region that caused it to delete the entry block,
-; but it does not anymore after the changes to handling of infinite loops in the
-; PostDominatorTree.
-; TODO: This should be either replaced with another IR or deleted completely.
-
-; RUN: opt -S -o - -structurizecfg -verify-dom-info < %s | FileCheck %s
-
-; CHECK-LABEL: @no_branch_to_entry_undef(
-; CHECK: entry:
-; CHECK-NEXT: br label %entry.orig
-define void @no_branch_to_entry_undef(i32 addrspace(1)* %out) {
-entry:
-  br i1 undef, label %for.end, label %for.body
-
-for.body:                                         ; preds = %entry, %for.body
-  store i32 999, i32 addrspace(1)* %out, align 4
-  br label %for.body
-
-for.end:                                          ; preds = %Flow
-  ret void
-}
-
-; CHECK-LABEL: @no_branch_to_entry_true(
-; CHECK: entry:
-; CHECK-NEXT: br label %entry.orig
-define void @no_branch_to_entry_true(i32 addrspace(1)* %out) {
-entry:
-  br i1 true, label %for.end, label %for.body
-
-for.body:                                         ; preds = %entry, %for.body
-  store i32 999, i32 addrspace(1)* %out, align 4
-  br label %for.body
-
-for.end:                                          ; preds = %Flow
-  ret void
-}
Index: llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
+++ llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
@@ -885,20 +885,7 @@
     handleLoops(false, LoopEnd);
   }
 
-  // If the start of the loop is the entry block, we can't branch to it so
-  // insert a new dummy entry block.
-  Function *LoopFunc = LoopStart->getParent();
-  if (LoopStart == &LoopFunc->getEntryBlock()) {
-    LoopStart->setName("entry.orig");
-
-    BasicBlock *NewEntry =
-      BasicBlock::Create(LoopStart->getContext(),
-                         "entry",
-                         LoopFunc,
-                         LoopStart);
-    BranchInst::Create(LoopStart, NewEntry);
-    DT->setNewRoot(NewEntry);
-  }
+  assert(LoopStart != &LoopStart->getParent()->getEntryBlock());
 
   // Create an extra loop end node
   LoopEnd = needPrefix(false);


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