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StructurizeCFG: Fix verification failure with some loops.
If the beginning of the loop was also the entry block of the function, branches were inserted to the entry block which isn't allowed. If this occurs, create a new dummy function entry block that branches to the start of the loop. llvm-svn: 195493
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@ -779,6 +779,20 @@ void StructurizeCFG::handleLoops(bool ExitUseAllowed,
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handleLoops(false, LoopEnd);
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}
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// If the start of the loop is the entry block, we can't branch to it so
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// insert a new dummy entry block.
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Function *LoopFunc = LoopStart->getParent();
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if (LoopStart == &LoopFunc->getEntryBlock()) {
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LoopStart->setName("entry.orig");
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BasicBlock *NewEntry =
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BasicBlock::Create(LoopStart->getContext(),
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"entry",
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LoopFunc,
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LoopStart);
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BranchInst::Create(LoopStart, NewEntry);
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}
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// Create an extra loop end node
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LoopEnd = needPrefix(false);
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BasicBlock *Next = needPostfix(LoopEnd, ExitUseAllowed);
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31
test/Transforms/StructurizeCFG/no-branch-to-entry.ll
Normal file
31
test/Transforms/StructurizeCFG/no-branch-to-entry.ll
Normal file
@ -0,0 +1,31 @@
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; RUN: opt -S -o - -structurizecfg < %s | FileCheck %s
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; CHECK-LABEL: @no_branch_to_entry_undef(
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; CHECK: entry:
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; CHECK-NEXT: br label %entry.orig
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define void @no_branch_to_entry_undef(i32 addrspace(1)* %out) {
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entry:
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br i1 undef, label %for.end, label %for.body
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for.body: ; preds = %entry, %for.body
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store i32 999, i32 addrspace(1)* %out, align 4
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br label %for.body
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for.end: ; preds = %Flow
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ret void
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}
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; CHECK-LABEL: @no_branch_to_entry_true(
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; CHECK: entry:
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; CHECK-NEXT: br label %entry.orig
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define void @no_branch_to_entry_true(i32 addrspace(1)* %out) {
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entry:
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br i1 true, label %for.end, label %for.body
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for.body: ; preds = %entry, %for.body
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store i32 999, i32 addrspace(1)* %out, align 4
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br label %for.body
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for.end: ; preds = %Flow
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ret void
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}
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